OA19228A - Point of care assays - Google Patents

Abstract

An immunoassay suitable for point of care to assess liver disease or function comprising contacting a blood sample from a subject with a specific binding agent that recognizes an epitope of ALTI, that is not recognized by rodent antibodies when the rodent antibodies are in the presence of human plasma, to form an antigenbinding agent complex and detecting the complex using a second or further binding agent linked to or comprising a detectable reporter; and detecting liver disease or liver function in the subject contingent upon the mass concentration of ALTI in the sample. Kits or devices comprising lagomorph antibodies or binding agents comprising the antigen binding component thereof suitable for measuring the mass concentration of ALTI in a blood sample from a subject to determine liver function.

Description

POINT OF CARE ASSAYS

FIELD

The field of the spécification is point of care testing and more specifically assays and kits for identifying abnormal levels of enzymes or abnormal liver function in subjects. Screening assays are also provided.

BACKGROUND

Bibliographie details of référencés in the subject spécification are also listed at the end of the spécification.

Reference to any prior art in this spécification is not, and should not be taken as, acknowledgement or any form of suggestion that this prior art forms part of the common general knowledge in any country.

Liver disease or hepatitis is a major healthcare burden worldwide. Liver disease can be caused by viruses (including hepatitis A, hepatitis B, hepatitis C, hepatitis D and hepatitis E viruses) or other infections, or by drug toxicity (including excessive alcohol use, and drugs used in treatment of conditions such as human immunodeficiency virus or tuberculosis infections), or through abnormal metabolic processes (including NonAlcoholic Fatty Liver Disease [NAFLD] and Nonalcoholic Steatohepatitis [NASH]). For example, more than 360 million people hâve chronic Hepatitis B and more than 200 million hâve chronic hepatitis C, with high risks of persistent liver disease leading to liver fibrosis, cirrhosis and hepatocellular carcinoma, while increasing levels of obesity hâve led to large increases in the prevalence of NASH, now estimated to affect more than 25% of the population worldwide (Younossi et al., 2016). Liver disease is also a major problem in management of pre-eclampsia, where monitoring of liver function in the mother is required in order to allow induction or surgical delivery of the neonate at the maximum gestational âge possible but before liver disease becomes too severe, where it would threaten the health of both the mother and the baby.

Effective drugs are becoming more widely available for treatment of hepatitis B and hepatitis C, and the presence of infections such as HBV or HCV can be determined with serological tests for antibodies or antigens and/or molecular tests for viral DNA or RNA. Many thérapies are also under development for conditions such as NAFLD and

NASH, while prompt delivery of neonates can be effective in pre-eclampsia. However a major hurdle to effective use of these drugs, thérapies and interventions is the identification of those patients who hâve the highest health risk and greatest need for therapy or intervention, because liver disease présents with non-specific signs and symptoms and cannot be diagnosed on clinical examination alone.

Liver disease is most conveniently detected and diagnosed by biochemical tests conducted on blood or plasma to detect the presence of abnormal amounts of liverspecific enzymes such as alanine aminotransferase (ALT), aspartate aminotransferase (AST) or gamma glutamyl transferase (GGT), or métabolites such as bilirubin. Using ALT as an example, the human ALT1 isoform is predominantly expressed in the cytosolic compartment of liver hépatocytes, and the destruction of hépatocytes during liver disease results in the release of soluble ALT into the plasma, where its enzymatic activity can be measured using a variety of biochemical test assay methods. In these methods, the enzymatic activity of the ALT converts a substrate into a product, and an instrument measures the change in color, absorbance or fluorescence ofthe substrate or product to calculate the concentration of ALT présent in the sample. This concentration is then compared to the normal, healthy levels expected under the test conditions and population being studied. These methods are well known in the art and are available in a wide range of automated and semi-automated analytical instruments that may use whole blood, plasma or sérum as samples. An ALT test has also been described in which a visible color reaction of substrate can be detected in a POC device without the need for an instrument, but the visual dynamic range of this test limits its usefulness to identifying samples with highly elevated ALT levels (>3 times upper limit of normal, or 120 IU/L) (Pollock et al 2012). A more préférable test would be able to discriminate samples relative to the cutoffs recommended by the European Association for the Study of the Liver (EASL), which recommends an upper limit of 40 IU/L ALT for management of chronic hepatitis B and other conditions.

However a major limitation of these methods is the general need for instruments for two purposes; (a) to conduct the enzymatic reaction at a fixed tempei attire, since enzyme activity is highly température sensitive, and (b) to measure the enzymatic products at exact times or under kinetic conditions to provide précisé measurements.

A further limitation in the case of ALT is the presence in humans of a second isoform, ALT2, which is more abundant in muscle tissues but is similarly released from damaged cells, for example following extreme exercise or heart failure. As the enzymatic assay does not distinguish between ALTl and ALT2 elevated levels of ALT2 enzymatic activity in blood, plasma or sérum may lead to a false diagnosis of liver disease. Even further, it is observed that ALT enzyme assays are not diagnostic in cases of severe disease where enzyme levels are diminished.

Therefore there is an unmet need for liver function or disease tests that would be applicable to use at the point of care (POC) or near POC, to expand access to liver function testing for resource-poor settings worldwide, and for convenient use in clinics even in resource-rich settings. Here we describe, inter alia novel methods and approaches that hâve allowed the development of a POC test for ALTl as a biomarker of liver disease, even severe liver disease, using the well-established technique of latéral flow immunochromatography, and with specificity for the ALTl isoform rather than the ALT2 isoform. These methods will be generally applicable to diagnostic tests for other liver enzymes and other enzymes and métabolites thereof that are required for measurements at point of care where enzyme activities cannot be assessed, or more broadly as described herein. Although suitable for point of care, the subject methods can be used in any convenient immunoassay format.

SUMMARY

Accordingly, in one aspect the spécification provides an immunoassay suitable for but not limited to point of care to detect and quantify a liver enzyme in a blood sample from a subject. In one embodiment, said assay comprises: (i) obtaining a blood sample from a subject, and (ii) detecting the presence and quantity of the liver enzyme in the sample. In particular, this is achieved by contacting the blood sample from a subject with a spécifie binding agent that specifically recognizes an epitope of the liver enzyme (antigen), that is not recognized by the majority of rodent antibodies when the rodent antibodies are in the presence of plasma. In one embodiment, the binding agent is an antibody formed in a rabbit or other lagomorph or is an immunoglobulin domain thereof. The binding agent binds to the liver enzyme even in the presence of human plasma and forms an antigen-binding agent complex. Then the presence and amount of the complex is detected using a second binding agent linked to a détectable reporter. In some embodiments, the spécifie binding agent and the second binding agent are the same. In the case of binding reagents that are polyclonal antibodies, the same préparation of polyclonal antibodies may be used for both antigen-binding and the détectable reporter.

In some embodiments, the mass concentration of a liver enzyme, such as ALTl or AST or GGT, is used to détermine whether a subject can be safely treated by a general practitioner/in the community or whether the subject needs to be treated by a specialist such as a hepatologist or gastroenterologist. Thus, if ALT levels are supranormal (specifically, for example, over 40 IU/L or the équivalent mass concentration) the subject needs to be treated by a specialist. Whereas, if the liver enzyme levels are normal, the subject can be treated by a general practitioner/in the community. In some embodiments, platelet levels are also assessed in the immune assay to provide a liver enzyme/platelet ratio, for example an APRI ratio (which is an AST: platelet ratio index, known in the art) as an indication of poor liver function/liver fibrosis.

As determined herein, rodent (murine) antibodies to human ALTl are substantially blocked from binding human ALTl by a component in human plasma. Accordingly, antibodies are employed in the présent methods that that do not recognize immuno-dominant régions of the antigen or do not compete with rodent/murine antibodies against the antigen. Thus, antibodies are employed that recognize an epitope of a liver enzyme even in the presence of human plasma. In one embodiment, this is achieved by developing antibodies in lagomorphs (rabbits). Suitable binding agents could also be developed by screening for binding in the presence of human plasma, as described herein. In another embodiment, non-immunodominant parts of liver enzyme antigens are employed to generate antibodies that are not inhibited by human plasma. Suitable screening and development methods are known in the art.

In one embodiment, the binding agent is an antibody or an antigen binding part thereof comprising an immunoglobulin domain known in the art, or another spécifie binding agent known in the art such as a ligand, receptor, chemical ligand, aptamer etc.

In one embodiment, the spécifie antibody or binding agent recognizes human ALTl and does not recognize human ALT2 or does not substantially recognize ALT2.

In one embodiment, the blood sample can be whole blood, plasma or sérum.

In one embodiment, the liver enzyme is selected from alanine aminotransferase (ALTl), aspartate aminotransferase (AST) and gamma glutamyl transferase (GGT).

In one embodiment, the mass concentration of liver enzyme is positively correlated with enzyme activity over a useful diagnostic range. This means that liver disease can be detected early when levels of liver enzymes are above the threshold for normal (a mass concentration équivalent to 40 1U/L in the case of ALT). Prior art assays are far less sensitive as ALT levels need to be 3-4 times higher than normal levels to be détectable by the assay.

In another embodiment, the présent spécification provides an immunoassay suitable for point of care to assess liver disease or function in a blood sample from a subject, said assay comprising:

(i) contacting a blood sample from a subject with a spécifie binding agent that specifically recognizes an epitope of a liver enzyme or a métabolite thereof, that is not efficiently or substantially recognized by rodent/mouse antibodies when the liver enzyme is in the presence of plasma (human plasma), to form an antigen/epitopebinding agent complex and detecting the complex using a second or further binding agent linked to or comprising a détectable reporter; and (ii) detecting liver disease in the subject when the mass concentration of the liver enzyme or métabolite exceeds a recognized reference level.

As determined herein, as the positive corrélation between ALT enzyme activity levels and liver disease and recognized reference levels are established, although not for severe liver disease, now the finding that ALTl mass concentration determined using the présent methods is also positively correlated with ALTl enzyme levels allows the user to détermine liver disease in measurements of either mass concentration or équivalent enzyme levels. In subjects with severe liver disease or at risk of having or likely to hâve severe liver disease, the mass concentration provides a more accurate and quantitative assessment of liver disease, or the progress with treatments then enzyme activity levels. Accordingly, reference levels may be expressed as mass concentrations or enzyme activity unit, or rations as appropriate. The skilled person will appreciate that reference levels and suitable controls are determined using standard approaches as a routine development task. Thus for example a comparison of ALTl mass concentration levels may be between subjects or groups of subjects to détermine reference levels, a test resuit may be compared with reference levels for healthy coneols or with controls that hâve a liver disease and thus higher or lower comparative levels can be expected depending upon the reference level selected.

In one embodiment, the spécifie binding agent does not compete effectively with murine antibodies generated against the antigen/enzyme.

In one embodiment, the antibody is selected by screening for lack of inhibition of the reactivity against the liver enzyme by human plasma.

In one embodiment, the liver enzyme is selected from alanine aminotransferase (ALTl), aspartate aminotransferase (AST) and gamma glutamyl transferase (GGT). That is, the examples disclose the results of testing for ALTl but AST or GGT could alternatively be tested.

In one embodiment, wherein the spécifie binding agent is a lagomorph antibody or comprises an antigen binding part thereof, or wherein the spécifie binding agent is a rabbit antibody or recognizes the same epitope as the rabbit antibody.

In one embodiment, the subject is human.

In one embodiment, the mass concentration of the liver enzyme or métabolite is positively correlated with the enzymatic activity for a subject without severe liver disease.

In one embodiment, and as determined herein using the subject method, the mass concentration of the liver enzyme or a métabolite thereof is positively correlated with increasing liver disease.

Generally a corrélation of not less than about 70% will be effective. Levels of 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% are contemplated.

In one embodiment, very high mass concentrations of liver enzymes or a métabolite thereof is diagnostic of advanced liver disease or liver failure. In contrast, liver enzyme levels are often reduced in advanced liver disease and enzyme testing would lead to false négative tests for liver disease.

In another embodiment, the spécification provides an immunoassay suitable for point of care to assess liver disease or function, said assay comprising:

(i) contacting a blood sample from a human subject with a spécifie binding agent that specifically recognizes an epitope of ALTl, that is not efficiently recognized by rodent antibodies when the ALTl is in the presence of human plasma, to form an antigen-binding agent complex and detecting the complex using a second or further binding agent linked to a détectable reporter; and (ii) detecting liver disease in the subject when the mass concentration of ALTl exceeds a recognized reference level.

In one embodiment, the spécifie binding agent is a rabbit antibody or comprises an antigen binding part thereof, or wherein the spécifie binding agent recognizes the same epitope as the rabbit antibody.

In one embodiment, the mass concentration ofthe ALTl is positively correlated with ALT enzymatic activity for a subject without severe liver disease.

In one embodiment, the mass concentration of ALTl is positively correlated with increasing liver disease.

In one embodiment, two or more liver enzymes or a métabolite thereof are assessed in the assay.

In one embodiment, reference levels équivalent to 40 IU/L ALT are contemplated. ALT activities of between 2 and 300 IU are contemplated including ail integers in between.

In one embodiment, the binding agent is an antibody or an antigen-binding fragment thereof, an antigen-binding construct such as an affimer or aptamer, a ligand or binding part thereof.

In one embodiment, the assay is an enzyme-linked immunosorbent (ELISA)type or immunochromatographic-type assay and the spécifie binding agent is immobilised on a support.

In one embodiment, the immunoassay is an ELISA- type or immunochromatographic-type, or microfluidic-type assay known in the art.

In one embodiment, the blood sample is contactée! with the binding agents by applying the blood sample to a sample portion of an immunochromatographic or microfluidic device wherein the device sample portion is operably connected to spaced capture portions of the device and whereby the components of the sample flow from the device sample portion to and through the device capture portions, and wherein one capture portion comprises the binding agent which specifically binds to the antigen in the sample such that the antigen is captured by the binding agent to form a binding agent-antigen complex in the capture portion.

In one embodiment, the amount of antigen complex is detected using binding agents such as an antibody or antigen-binding fragment, ligand or affimer that specifically binds the antigen and directly or indirectly provide a détectable signal that can be quantified visually or photometrically including fluorometrically (by instrument reader).

In one embodiment visual quantitation is relative to an internai reference (a similar assay is disclosed in US Patent 8,409,818).

In one embodiment, the spécifie binding agents are conjugated to a détectable marker or microparticles comprising a détectable marker, that provide a détectable signal.

In one embodiment, the capture portion is a test line.

In another aspect, platelet levels are assessed within the assay.

In one embodiment, the ratio of the visual or photometrically calculated signal from the antigen test line and the visual or photometrically calculated signal from the platelet marker test line provides a liver enzyme-platelet ratio index.

In one embodiment the liver enzyme-platelet ratio index provides a diagnosis of liver fibrosis. In one embodiment of this assay, the liver enzyme is ALT1 or AST.

In one embodiment the présent invention provides a kit for measuring the mass concentration of ALT1 or for detecting liver disease comprising (i) a chromatographie device comprising a porous membrane operably connected to a sample portion, one or more capture (test) portions, and optionally one or more of the following, a conjugate (détection marker) portion, a sucker portion, a suitable control portion and optionally a cell lysis or solubilisation portion, and (ii) a lagomorph antibody that recognizes an epitope of ALTl and forms an ALTl-rabbit antibody complex or a binding agent comprising the antigen binding component thereof, and (iii) optionally instructions for using the device to détermine liver function.

In one embodiment, the device is suitable for reverse or latéral flow immunochromatographic formats.

In another embodiment, the présent invention provides a kit comprising (i) a chromatographie device comprising a porous membrane or a microfluidic device operably connected to a sample portion, two or more capture (test) portions, and optionally one or more of the following; a conjugate (détection marker) portion, a sucker portion, a suitable control portion and optionally a cell lysis or solubilisation portion, and (ii) a spécifie lagomorph antibody or binding agent that comprises the antigen binding part thereof or spécifie binding agent that recognizes an epitope of a liver enzyme or métabolite, such as one that is not recognized by rodent antibodies when the liver enzyme or métabolite are in the presence of plasma, and forms a liver enzyme-antibody/binding agent complex, and a second binding agent that binds specifically to platelets in the sample and forms a platelet marker-binding agent complex wherein the binding agents are either immobilised to separate capture portions and/or contained within conjugate portions and (iii) optionally instructions for using the device to détermine the liver enzyme-platelet ratio index as a measure of liver fibrosis.

In one embodiment the ratio developed is the AST/platelet ratio or the ALTl/platelet ratio, or combinations thereof.

In one embodiment the kit is a reverse or latéral flow immunochromatographic format.

In one embodiment, the binding agent comprises an immunoglobulin domain.

In one embodiment, the kit employs any one of the assays described herein or known variants thereof.

In one embodiment, the spécification provides a method of treating liver disease, the method comprising (i) assessing the mass concentration of ALTl in a blood sample from a subject comprising contacting a blood sample from a human subject with a lagomorph antibody that specifically recognizes an epitope of ALTl in the presence of

ΙΟ plasma to form an antigen-antibody complex and detecting the complex using a second binding agent linked to a détectable reporter, and (ii) recommending a treatment program or treating the subject if the level of ALTl exceeds a normal/control ALTl level.

In one embodiment, the spécification provides a method of treating liver disease, the method comprising (i) assessing the mass concentration of ALTl in a blood sample from a subject comprising contacting a blood sample from a human subject with a lagomorph antibody that specifically recognizes an epitope of ALTl in the presence of plasma, or a binding agent comprising the antigen binding component thereof, to form an antigen-antibody complex and detecting the complex using a second or further (eg, third) binding agent linked to or comprising a détectable reporter, and (ii) recommending a treatment program or treating the subject contingent upon the observed level or mass concentration of ALTl in the subject.

In one embodiment, the method is sensitive and able to detect a mass concentration of human ALTl équivalent to about 40 IU/L ALT or between 20 and 200 IU/L ALT.

Suitable treatments are known in the art and include anti-viral agents, dietary changes, physical exercise, yoga, anti-obesity drugs, glucose control agents, lipid lowering drugs, cytoprotective agents, anti-diabetes médication such as anti-TNF monoclonal antibodies, adenosine System drugs, rénal transport glucose blockers such as PPAR agonists, herbal products, antihypertensive agents, peripheral cannabinoid agonists, thyroid hormone analogues, farnesoid X receptor agonists, insulin sensitizing agents, iron déplétion drugs, among others.

Conditions affecting the liver include, without limitation hepatitis, preeclampsia, drug toxicity, metabolic disease, non-alcoholic fatty liver disease, nonalcoholic steatohepatitis, liver fibrosis, cirrhosis, hepatocellular carcinoma etc.

In another embodiment, the présent spécification provides a method of screening for binding agents that are substantially not inhibited from antigen binding by plasma: said method comprising contacting antigen and a potential antigen binding agent in the presence of different concentrations of plasma to détermine whether the binding agent can bind the antigen in the presence of plasma.

H

In one embodiment the binding agent is an antibody, monoclonal antibody or antigen binding part thereof, peptide ligand, nucleic acid binding ligands.

In one embodiment, methods of selecting antibodies suitable for the subject assays are determined by screening for lack of substantial inhibition of their reactivity against ALT by human plasma. In this way antibody reagents are developed from any species including mouse, rat, rabbit that are not affected by plasma (i.e., they recognise non-immunodominant sites that are not blocked by plasma).

In one embodiment, the présent invention provides a method of selecting binding reagents other than antibodies suitable for use in the assays as described herein, by screening for lack of substantial inhibition of their reactivity against ALTl by human plasma. In one embodiment convenient binding agents include developing protein ligands by phage display or related methods, nucleic acid aptamer ligands, chemical ligands etc.

In one embodiment, the spécification provides a method of screening for antibody or other spécifie binding agents that are substantially not inhibited from antigen binding by plasma, the method comprising contacting antigen and a potential antigen binding agent in the presence of different concentrations of plasma to détermine whether the binding agent can bind the antigen in the presence of plasma.

In one embodiment, the antigen is a liver enzyme such as ALTl.

Each embodiment in this spécification is to be applied mutaùs mutandis to every other embodiment unless expressly stated otherwise.

The above summary is not and should not be seen in any way as an exhaustive recitation of ail embodiments of the présent disclosure.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 illustrâtes ELISAs showing poor corrélation of apparent ALT mass versus ALT enzymatic activity and the effect of plasma dilution. Upper panel: ELISA using monoclonal antibody 4A9 capture, monoclonal antibody M02A détection, for four human plasma samples with different enzymatic ALT levels, or rabbit sérum as négative control. Note strong inhibition of antigenic reactivity in less diluted samples (bell-shaped curve or prozone) and lack of corrélation between enzymatic ALT levels and antigenic reactivity observed. Lower panel: Commercial Elabscience ELISA kit for ALT, for three human plasma samples with different enzymatic ALT levels. Note variable inhibition of antigenic reactivity in less diluted samples (bell-shaped curve or prozone) and lack of corrélation between enzymatic ALT levels and antigenic reactivity observed.

Figure 2 illustrâtes ELISAs showing inhibition of mouse monoclonal antibody reactivity against ALT (Lee Bioscience) that was coated directly on ELISA plates, depending on the concentration of human plasma also added. Each of the antibodies shown demonstrated sensitivity to the presence of patient sera even at l :8 dilution of sample. Similar results were observed for 12 other mouse monoclonal antibodies against ALT.

Figure 3 (A-C) provides a comparison of the amino acid sequence of ALTl in humans and in mice. Alignment of the sequences for human ALTl and ALTl from mouse (Figure 3A), rat (Figure 3B) or ALT2 from Rabbit (Figure 3C), noting that rabbits do not hâve a close homolog of the ALTl gene and express only ALT2. Note the close identity and similarity of ALTl from humans, mice and rats, whereas rabbit ALT2 is only 70% identical leading to improved immunogenicity of the many régions of différence compared to human ALTL

Figure 4 illustrâtes that rabbits produced robust antibody responses after immunization with purified human ALTL Rabbits immunised with recombinant ALTl demonstrate high levels of antibody in their sérum (not shown) or purified IgG. After labelling of the purified IgG with biotin, an ELISA using the format shown was used to compare the ability of each of the rabbit test bleeds to capture and detect ALT (Lee Bioscience). Note that ail rabbit samples were able to capture and detect the Lee ALT when diluted in laboratory buffers without plasma.

Figure 5 illustrâtes using the same ELISA format as Figure 2, we demonstrate that rabbit polyclonal antibodies reactivity against ALT are not affected by the presence of human plasma at high concentrations (l:2, l:4 or l:8 dilutions of plasma give the same reactivity as no added plasma).

Figure 6 illustrâtes a schematic of the détection System utilized in a lateral-flow, immunochromatographic test strip.

Figure 7 illustrâtes examples of latéral flow immunochromatographic test for détection of ALT in plasma or whole blood. Upper panel; photos of test strips run in cassettes and showing different levels of test activity (line adjacent to 350 label) for three samples with 155 U/L, 60 U/L or I0 U/L ALT. Middle panel: assay method. Lower panel: Visual corrélation of ALT enzymatic activity (U/L) versus intensity of test line reactivity for patient samples with >30 U/L (n=7) and only faint reactivity for lower ALT levels (n=4).

Figure 8A-B illustrate measurement of test line activity using the AX-2 instrument (shown in Figure 10C) demonstrates significant corrélation between ALT enzymatic activity (U/L) and the test line peak height (Peak). Samples from hepatitis patients in Melbourne (n=48, Figure 8A) or Nanjing (n=174, Figure 8B) both demonstrate significant levels of corrélation, with some samples showing higher peak heights than expected from the overall corrélation, consistent with elevated levels of total ALT versus enzymatic ALT in more progressive liver disease.

Figure 9 illustrâtes the CD4 T-cell test, the amount of CD4 antigen represented at the test (T) line is directly proportional to the number of CD4 T-cells. The test signal is then compared visually or by instrument reader versus one or more référencé lines representing clinically relevant levels of CD4 T-cells, in the figure the example of 350 T-cells per μΐ which is recommended by WHO for prioritisation of antirétroviral therapy in HIV infection. Similarly, for ALT référencé line is employed corresponding to one or more clinically relevant amounts of ALT, including the 40 lU/L level recommended by EASL. A schematic of the proposed semi-quantitative ALT test is shown in Figure 10.

Figure 10 illustrâtes the potential format for latéral flow immunochromatographic POC test for ALT. Visitect CD4 test (A), expanded view and schematic of proposed ALT test (B, red boxes), and Axxin AX-2 reader (C). For visual interprétation an intensity for the ALT line greater than the Référencé line might be considered to be diagnostic of ALT levels above a cutoff such as 40 IU/L, however with the use of a reader such as the Axxin AX-2 reader (Figure 10C) a fully quantitative resuit can be determined.

Figure 11A-B illustrate the design of ELlSAs that can be used to identify polyclonal antibodies, monoclonal antibodies or other binding agents that are suitable for détection of ALTl in human plasma samples. Using the format shown schematically in Figure 11 B, ALT is coated on an assay surface followed by various dilutions of human plasma, before addition of the binding agent (e.g. antibody) and then détection reagents. Comparison of the amount of binding in the presence of plasma versus no plasma can demonstrate that binding reagents are suitable for the purpose, as shown in the upper left panel of Figure l IA for rabbit anti-rALT (affinity purified) with no effect by plasma, versus reagents that are unsuitable for the purpose as shown for a range of monoclonal antibodies in the remaining panels, where there was variable levels of inhibition in the presence of plasma (Hu03, 5H2, 3H12, 6B5 monoclonal antibodies) or poor reactivity even in the absence of plasma (3B4 monoclonal antibody).

Figure 12 illustrâtes the specificity of the ALTl binding assay for ALTl and the lack of reactivity for enzymatically équivalent levels of ALT2 in an EL1SA assay. Unpurified human ALTl or human ALT2 (SEQ ID: 6) representing équivalent levels of enzymatic ALT activity are coated on ELISA plates followed by rabbit antibodies against ALTl, ELISA reactivity is only seen for ALTl and not ALT2 for ail concentrations of enzymatic ALT, demonstrating specificity of the reagent and the assay for ALTl and not ALT2.

Figure 13 illustrâtes the specificity of the ALTl binding assay for ALTl and the lack of reactivity for enzymatically équivalent levels of ALT2 in an immunographic strip assay. Unpurified human ALTl or human ALT2 (SEQ ID: 6) representing équivalent levels of enzymatic ALT activity are subjected to the immunochromatographic assay as in Figure 7, only ALTl is detected in the immunochromatographic test.

KEY TO SEQUENCE LISTING

SEQ ID NO: 1 amino acid sequence of human alanine aminotransferase 1 (residues 1 - 496)

SEQ ID NO: 2 amino acid sequence of mouse alanine aminotransferase I

SEQ ID NO: 3 amino acid sequence of rat alanine aminotransferase l

SEQ ID NO: 4 amino acid sequence of human alanine aminotransferase l (residues 17 - 496)

SEQ ID NO: 5 amino acid sequence of rabbit alanine aminotransferase 2

SEQ ID NO: 6 amino acid sequence of human alanine aminotransferase 2

DISCUSSION OF EMBODIMENTS

The subject disclosure is not limited to particular screening procedures for agents, spécifie formulations of agents and various medical méthodologies, as such may vary.

Throughout this spécification, unless the context requires otherwise, the word comprise, or variations such as comprises or comprising, will be understood to imply the inclusion of a stated element or integer or group of éléments or integers but not the exclusion of any other element or integer or group of éléments or integers. By consisting of' is meant including, and limited to, whatever follows the phrase consisting of'. Thus, the phrase consisting of' indicates that the listed éléments are required or mandatory, and that no other éléments may be présent. By consisting essentially of' is meant including any éléments listed after the phrase, and limited to other éléments that do not interfère with or contribute to the activity or action specified in the disclosure for the listed éléments.

Reference herein to an antibody includes a whole antibody or an antigen binding part of an antibody, an immunoglobulin domain of an antibody as known in the art.

As used herein the singular forms a, an and the include plural aspects unless the context clearly dictâtes otherwise. Thus, for example, reference to a composition includes a single composition, as well as two or more compositions; reference to an agent includes one agent, as well as two or more agents; reference to the disclosure includes single and multiple aspects of the disclosure and so forth.

Unless defined otherwise, ail technical and scientific terms used herein hâve the same meanings as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Any materials and methods similar or équivalent to those described herein can be used to practice or test the présent disclosure. Practitioners are particularly directed to and Ausubel et al., Current Protocols in Molecular Biology, Supplément 47, John Wiley & Sons, New York, 1999; Colowick and Kaplan, eds., Methods In Enzymology, Academie Press, Inc.; Weir and Blackwell, eds., Handbook of Experimental Immunology, Vols. I-IV, Blackwell Scientific Publications, 1986; for définitions and terms of the art and other methods known to the person skilled in the art.

The clinical utility of tests for ALT and other liver disease markers is well demonstrated by the large number of instruments and tests available and in widespread use, but ail these tests are designed for use in laboratory or clinical facilities with reliable power supplies, trained technicians and other infrastructure that are commonly lacking in resource-poor settings. Furthermore, transportation of blood or plasma to centralized facilities for testing is reliant on fast, refrigerated transport to maintain the enzymatic activity of the samples.

Kim et al., 2009) reported tests in the format of enzyme-linked immunosorbent assays (ELISAs) for ALT mass concentration using combinations of monoclonal antibodies (MAbs) produced in mice. However a striking feature of the work by Kim et al. is the observation that under the conditions of their test, there was very low corrélation between ALT enzymatic activity and mass concentration. Similarly, Hu et al (2016) reported a lateral-flow, immunochromatographic test for ALT1 using combinations of monoclonal antibodies (MAbs) produced in mice where there was also very low corrélation with enzymatic ALT levels.

The biochemical tests are not accurate in subjects with severe or progressed liver disease and enzyme fonction is reduced. The authors of Kim et al. observed that despite low corrélation with enzymatic ALT, there was good utility of the ALT ELISA for detecting patients with more severe forms of viral hepatitis (cirrhosis and hepatocellular carcinoma), where the ALT mass concentration was increased but the amount of enzymatic ALT was somewhat reduced. The major need for liver disease testing is to identify patients before they reach such advanced stages of liver disease, for example EASL recommends an upper limit of 40 IU/L ALT for management of chronic hepatitis B, and similar needs exist for liver enzyme tests in drug toxicity, preeclampsia and other acute or chronic conditions.

In addition, healthcare workers will hâve an expectation that a new ALT test should show a reasonable level of corrélation with the established technology of enzymatic testing. Furthermore it will be appreciated that in accordance with the présent disclosure, détection of excessive amounts of ALT mass concentration provides additional clinical utility in more advanced forms of liver disease, such as chronic viral hepatitis. The immunochromatographic test for ALTl as described by Hu et al (2016) would not meet this expectation because the authors describe an assay that exhibits a very low corrélation with enzymatic ALT levels.

Commercially-available ELISAs for measurement of ALT in human plasma also exhibit very poor corrélation with enzymatic ALT levels, and surprisingly yield results that are highly dépendent on the sample dilution used for sérum or plasma (see Figure l).

Immunoassays are a useful lorm of assay that exploit the specificity, stiength and diversity of antibody-antigen reactions to analyze samples and detect spécifie components therein. A wide range of immunoassay techniques aie available, such as those classically described in Wild D. The Immunoassay Handbook Nature Publishing Group, 2001 and subséquent innovations. More recent innovations are in the area of antigen binding fragments comprising immunoglobulin domains and deiivatives thereof. Peptide aptamers, affimers, and chemical ligands are also contemplated and provide advantages in the area of production and attributes such as specificity, longevity/stability and sensitivity.

Latéral (low assays and more recently non-lateral llow and miciofluidics provide a useful set up for biological assays. Such assays can be qualitative, quantitative or semi quantitative. In microfluidic devices. small volumes of liquid are moved through microchannels generated in. for example, a chip or cartridge. A wide range of détection reagents are available including métal nanopaiticles, coloured or luminescent materials. Résonance enhanced adsorption (R.EA) of bioconjugated métal nanoparticles offers rapid processing times and other advantages. Devices may be combined with barcode technologies to identify the patient and the analyte being tested.

Computer software and hardware for assessing input data are encompassed by the présent disclosure.

A wide range of methods for the détection of antibody to spécifie antigens/enzymes are also known. For example, the enzyme-linked immunosorbent assay (ELISA). Western and dot blot assays, and radio-immunoassay (RIA) are routinely used in laboratories. Arrays and high throughput screening methods are also employed.

Qualitative assays providing an intermediate or definitive diagnosis require integrated cutoffs. gates or Windows that permit scoring of samples as likely or not to hâve a condition. Instrument readers and software are often employed to collate data and process it through a diagnostic algorithm or decision tree.

For point of care diagnostics it is not feasible to directly monitor enzyme activities as this requires quite sophisticated assessment. Because most enzymes, including enzymes of interest are proteins, it is proposed that the amount of such enzymes can be detected by serological tests that detect the protein as an antigen (mass concentration), rather than by enzymatic activity. Most commonly, serological tests for détection of antigens will use a pair of binding agents and especially monoclonal antibodies produced in mice or other species to first bind, and secondly detect the antigen in question. A surprising and novel observation described herein is of a strong interférence by human plasma on the level of antigenic reactivity with a range of mouse monoclonal antibodies. This led the inventor/s to conclude that interfering substance(s) in plasma bind to and obscure one or more of the antigenic epitopes in ALTl that are able to induce an immune response in mice. It will be further appreciated that this general method can be applied to the development of test assays and especially POC test assays against other enzymes, including but not limited to other liver-specific enzymes that may be used for different purposes. For example, aspartate aminotransferase (AST) may be used instead of ALT for measurement of liver disease.

The présent inventor/s reasoned that one or more factors présent in human plasma may interfère with the binding of murine antibody to ALT and other antigens, thus preventing the development of useful sensitive assays for ALT mass concentration using this approach.

The surprising and novel observation of the strong interférence by human plasma on the level of ALT antigenic reactivity with a range of mouse MAb led the inventor/s to conclude that interfering substance(s) in plasma may bind to and obscure one or more of the antigenic epitopes in ALTl that are able to induce an immune response in mice.

The inventor/s devised a solution to this problem by taking advantage of the known fact that rabbits do not hâve a homolog of the human ALTl protein or gene, and instead hâve only a homolog of the ALT2 protein that appears to provide the relevant biochemical functions in ail forms of body tissues. Thus, ail parts of the human ALTl protein (and especially the surface part of the protein) may be expected to be immunogenic in rabbits, in contrast to the situation in mice where only the régions of différence between mouse and human ALTl will be immunogenic. As shown in Figure 4, rabbits produced robust antibody responses after immunization with purified human ALTl. In one embodiment, an ELISA was established using rabbit anti-ALT to capture ALT in human plasma, and biotin-labelled rabbit anti-ALT and horseradish peroxidase-labelled streptavidin to detect the captured ALT. As shown in Figure 5, this ELISA was not adversely affected by the presence of human serum/plasma, making it suitable for the analytical détermination of ALT mass concentration in human clinical specimens. Due to the sensitivity of the test, it would now be possible to detect diagnostically useful levels of ALTl in subjects. To enable détection of ALTl at the point of care, Figure 6 illustrâtes the détection method for ALTl using colloïdal gold as an alternative détection System to ELISA. Using this colloïdal gold test format, it was shown that it is possible to detect ALT in human plasma or whole blood in the format of a lateral-flow, immunochromatographic test strip (Figure 7).

While the use of an instrument such as the AX-2 instrument in combination with the POC ALT test is désirable for many reasons, there is also a need for a test that can give a simple, visual readout of normal (healthy) versus abnormal (elevated, unhealthy) levels of ALT, for example < 40 IU/L, or > 40 IU/L respectively according to EASL guidelines. This is readily achieved using methods previously described in development of a latéral flow, POC test for measuring CD4 T-cells (US Patent 8,409,818 and other territories) (Figure 9). This provides the additional advantage that similar instruments, test cartridges and manufacturing methods can be used for the various test devices.

In one embodiment, the assays and kits are contemplated that employ one or more of flow cytométrie quantification techniques (eg. fluorescent microbeads), microfluidic, cartridge, IFA, ELISA-type, and latéral flow devices, etc optionally together with an instrument reader and/or associated software to evaluate and compare ALTl and or platelet levels.

It will be appreciated by one skilled in the art that this test can be further modified to provide for simultaneous measurement of ALT and one or more other relevant biomarkers, for example ALT plus platelet levels which are both important markers in management of pre-eclampsia.

It will be further appreciated that this general method can be applied to the development of test assays and especially POC test assays against other enzymes, including but not limited to other liver-specific enzymes that may be used for different purposes. For example, aspartate aminotransferase (AST) may be used instead of ALT for measurement of liver disease.

In addition, the combination of ALT plus platelet levels may provide a useful non-invasive biomarker for the extent of liver fibrosis, by analogy with enzymatic AST and platelet levels where the AST-platelet ratio index (APRI) score is the arithmetic product of the sample resuit for AST (divided by normal level), multiplied by 100 and divided by the platelet count (in 10⁹ per ml). APRI score is recommended by the World Health Organisation for the non-invasive measurement of liver fibrosis where there is not access to alternative methods such as Fibroscan (specialised ultrasound). Similarly, a POC test for APRI would combine the measurement of AST levels as described herein for ALT, and platelet levels.

While the ALT assays described herein hâve made use of affinity-purified polyclonal antibodies produced in rabbits, it will be understood that monoclonal antibodies or other antigen binding agents known in the art may be used. Techniques for the production of rabbit monoclonal antibodies are now available, and it is expected that rabbit MAbs against ALTl could be readily obtained due to the lack of endogenous ALTl in the rabbit. However in mice, the species most commonly used for production of MAbs, the presence of endogenous ALTl results in most MAbs being directed against epitopes that may be susceptible to blocking by factor(s) présent in human plasma, and this is likely to be true also in rats that also express ALTL However the assays described herein for measurement of ALTl and especially the ELISA assays allowed us to develop a novel assay for the screening and sélection of antibodies and especially MAbs that are not susceptible to such plasma blocking and inhibition, and thus suitable for use in clinical assays such as the ALT assays described here.

As shown in Figure 11, when purified recombinant ALT is coated on an ELISA plate followed by sequential addition of human plasma (or no plasma as control) and a suitable dilution of the antibody or MAb of interest, the level of inhibition caused by addition of plasma can be determined, and antibody préparations or MAbs that are not substantially inhibited can be identified as a resuit. It will be appreciated by one skilled in the art that the saine technique could be applied to antibodies produced in any animal species or by recombinant means, and also to non-antibody binding agents such as affimers, aptimers, peptide ligands identified by phage display and other methods, or nucleic acid binding ligands identified by various new methods.

Immunoassays can be doue in any convenient format known in the art. These include Western blots, immunohistochemical assays and ELISA assays. The use of monoclonal antibodies in an immunoassay is widespread because of the abilîty to produce them in large quantifies and the homogeneity of the product. Polyclonal antibodies are also widely used. The préparation of hybridoma cell lines for monoclonal antigen production is derived by fusing an immortal cell line and lymphocytes sensitized against the antigen of interest (in a non-limiting example the antibody is in the case of CD4 polypeptides, peptides I or 2 or homologs. dérivatives, variants thereof) or can be doue by techniques which are well known to those who are skilled in the art. (See, for example, Douillard and Hoffman, Basic Facts about Hybridomas, in Compendium ot Immunology Vol. Il, ed. by Schwartz. 1981; Kohler and Milstein, Nature 256: 495-499. 1975; European Journal of Immunology 6: 51 l519, 1976 or more recent référencés Sambrook, Molecular Cloning: A Laboratory Manual, 3^rd Edition. CSHLP, CSH, NY, 2001).

The presence of complexes may be evaluated using ELlSA-type procedures. A wide range of immunoassay techniques are availabié as can be seen by reference to U.S. Pat. Nos. 4,016,043. 4,424.279 and 4,018,653. These include both single-site and two-site or sandwich assays of the non-competitive types, as well as in the traditional compétitive binding assays.

Sandwich assays are among the most useful and commonly used assays. A number of variations of the sandwich assay technique exist. and ail are intended to be encompassed herein. Briefly, in a typical forward assay. an antibody is immobilized on a solid or semi-solid substrate and the sample to be tested brought into contact with the bound molécule. After a suitable period of incubation, for a period of time sufflcient to allow formation of an antibody-antigen complex. a second antibody spécifie to the antigen. labelled with a reporter molécule capable of producing a détectable signal is then added (before or after a washing step) and incubated, allowing time suificient for the formation of another complex of antibody-antigen-labelled antibody. Any unreacted material may be washed away. and the presence of the marker is determined by observation of a signal produced by the détectable marker (reporter molécule). The results may be qualitative or quantitative, by simple observation of the visible signal, or may be quantitated by comparing with a control sample containing known amounts of marker. Variations on the forward assay include a simultaneous assay, in which both sample and labelled antibody are added simultaneously to the bound antibody. lhese techniques are well known to those skilled in the art. including any minor variations as will be readily apparent. In accordance with the présent invention, the sample is generally a biological sample comprising biological fluid. and is most conveniently a whole blood sample such as capillary or venons blood that may optionally be treated with an anticoagulant.

In a typical forward sandwich assay. a first antibody having specificity for a marker is either covalently or passively bound to a solid or semi-solid support. The support is typically glass or a polymer, the most commonly used polymers being nitrocellulose, cellulose, polyacrylamide. nylon, polystyrène, polyvinyl chloride. polypropylene or mixture or dérivatives of these. The solid supports may be in the form of tubes, beads. dises or microplates, or any other surface suitable for conducting an immunoassay. The binding processes are well-known in the art and generally consisi of cross-linking covalently binding or physically adsorbing the polymer-antibody complex to the solid surface which is then washed in préparation for the test sample. An aliquot of the sample to be tested is then added to the solid phase complex and incubated for a period of time sufficient (e.g. 2-40 minutes or overnight if more convenient) and under suitable conditions (e.g. from room température to about 37° C. including 25° C.) to allow binding of any subunit présent in the antibody. Following the incubation period, the antibody subunit solid phase is washed and incubated with a second antibody spécifie for a portion of the antigen. The second antibody is linked to a détectable marker which is used to indicate the binding of the second antibody to the antigen.

An alternative method involves immobilizing the target molécules in the biological sample and then exposing the immobilized target to spécifie antibody which may or may not be labelled with a détectable marker. Depending on the amount of target and the strength of the signal from the détectable marker. a bound target may be détectable by direct labelling with the antibody. Alternatively. a second labelled antibody. spécifie to the first antibody is exposed to the target-first antibody complex to form a target-first antibody-second antibody tertiary complex. The complex is detected bv the signa! emitted by the reporter molécule. A significant improvement of the beadbased methods involves tagging each bead with a unique identifier tag, such as an oligonucleotide or electrophoretic tag, so as to facil itate identification of the amino acid sequence of each library member. These improved bead-based methods are desciibed in International Publication No. WO 93/06I2l.

In other embodiments, the method is a liquid phase method. In one example of a liquid phase immunoassay (see for example U.S. Pat. No. 6,632,603) the sample is contacted with an agent capable of binding a marker and a detector agent comprising a visuallv détectable agent such as colloïdal gold or silver labelled. The test sample is applied by flowing onto a defmed zone of an insoluble porous support film having a pore size impassable to a complex formed between the marker and its target, and if présent, with a binding substance and a detector substance, but passable to the binding substance and detector substance while remaining uncomplexed in the absence of the desired target. If the target is présent in the test specimen. the detector substance binds with the target and the binding substance to form a visually inspectable complex on the surface of the porous support film. After application ol the test sample to the porous support, the surface of the porous support is visually inspected for colour to détermine the presence and quantity or the absence of the marker being assayed.

In another assay, magnetic antibodies that bind to markers are used to tag markers and a high T_c superconducting quantum interférence device is used to measure the amount of free and bound antibody and hence the presence or level of CSAP. A liposome immunomigration. liquid-phase compétition strip immunoassay is, for example, described in Glorio-Paulet et al J Agric hood Chem 48 (5).1678-1682, 2000.

General formats and protocols for the conduct of various formats of ELISA are disclosed in the art and are known to those of skill in the field of diagnostics. For example, reference may be made to Chapter 11 of Ausubel (E,d) Current Protocols in Molecular Biology, 5^th Edition. John Wiley & Sons, Inc, NY, 2002. Rundstrôm, G et al. describe latéral Flow immunoassay using Europium (111) Chelate Microparticles and Time-Resolved Fluorescence for eosinophils and neutrophils in Whole Blood. Clinical Chemistry 53, 342-348 (2007), incorporated herein.

The term Mevel” or '‘levels also encompasses ratios of level/s of biomarkers.

ECLLA, ELISA and Luminex LabMAP immunoassays are examples of suitable assavs to detect levels of AL I L In one example, a first spécifie binding agent is attached to a support surface and a second binding reagent/antibody comprising a détectable group binds to the first antigen binding agent . Examples of detectablegroups include. for example and without limitation: fluorochromes, enzymes, epitopes for binding a second binding reagent (for example, when the second binding reagent/antibody is a mouse antibody, which is detected by a fluorescently-labeled antimouse antibody). for example an antigen or a member of a binding pair, such as biotin and avidin. The surface may be a planar surface, such as in the case of a typical gridtvpe array (for example, but without limitation, 96-welI plates and planar micioaiiays) or a non-planar surface, as with coated bead array technologies, where each species of bead is labelled with, for example, a fluorochrome (such as the Luminex technology described in U. S. Patent Nos. 6,599. 331,6, 592.822 and 6,268, 222). or quantum dot technology (for example, as described in U. S. Patent No. 6,306. 610). Such assays may also be regarded as laboratory information management Systems (LIMS):

In the bead-type immunoassays, the Luminex LabMAP System can be utilized. The LabMAP System incorporâtes polystyrène microspheres that are dyed internally with two spectrally distinct fluorochromes. Using précisé ratios of these fluorochromes, an array is created consisting of different microsphere sets with spécifie spectral addresses. Each microsphere set can possess a different reactant on its surface. Because microsphere sets can be distinguished by their spectral addresses, they can be combined, allowing up to 100 different analytes to be measured simultaneously in a single reaction vessel. A third fluorochrome coupled to a reporter molécule quantifies the biomolecular interaction that has occurred at the microsphere surface. Microspheres are interrogated individually in a rapidly flowing fluid stream as they pass by two separate lasers in the Luminex analyzer. High-speed digital signal processing classifies the microsphere based on its spectral address and quantifies the reaction on the suiface in a few seconds per sample.

The subject contemplated herein is generally a human subject and may also be referred to as a patient, individual or récipient. Ihe human subject may be néonatal or an infant, child, adolescent, ieenager, young adult, adult or elderly adult of male or female gender. Control subjects are often selected groups of subjects referred to as a population of subjects/patients. Test samples are generally from subjects suspected of having or being at risk of liver disease, for example, hovvever samples may also be collected from subjects in individual or general population screening to exclude liver disease. Control samples may reflect different subgroups such as subjects with sever liver disease, hepatitis etc. Any subject group can be usefully employed as a control population including ”unhealthy subjects such as immunocompromised or aged populations.

The binding agent may conveniently be an antibody or an antigen-binding fragment thereof. Other suitable binding agents are known in the art and include antigen binding constructs such as affimers. aptamers. As described herein assays are provided for screening potential spécifie binding agents for their ability to bind ALl’l in the presence of human (or other species as appropriate) plasma to enable the method.

The term binding agent and like ternis, refers to any compound. composition or molécule capable of specifically or substantially specilïcally (that is with limited cross-reactivity) binding to an epitope on the biomarker. The binding agent” generally has a single specificity. Notwithstanding, binding agents having multiple specificities for two or more biomarkers are also contemplated herein. The binding agents (or ligands) are typically antibodies, such as monoclonal antibodies. or dérivatives or analogs thereof. but also include, without limitation: Fv fragments: single chain Fv (scFv) fragments; Fab' fragments; F(ab’)2 fragments; humanized antibodies and antibody fragments; camelized antibodies and antibody fragments, and multivalent versions of the foregoing. Multivalent binding reagents also may be used. as appropriate, including without limitation: monospecific or bispecific antibodies; such as disulfide stabilized Fv fragments. scFv tandems [(scFv) 2 fragments], diabodies. tribodies or tetrabodies. which typically are covalently linked or otherwise stabilized (i.e. leucine zipper or hélix stabilized) scFv fragments. Binding agents also include aptamers, as are described in the art.

Methods of making antigen-specifïc binding agents, including antibodies and their dérivatives and analogs and aptamers, are well-known in the art. Polyclonal antibodies can be generated by immunization of an animal. Monoclonal antibodies can be prepared according to standard (hybridoma) methodology. Antibody dérivatives and analogs, including humanized antibodies can be prepared recombinantly by isolating a DNA fragment from DNA encoding a monoclonal antibody and subcloning the appropriate V régions into an appropriate expression vector according to standard methods. Phage display and aptamer technology is described in the literature and

In some embodiments, a chromatographie device is provided comprising material which has a pore size which allows or facilitâtes capillary flow of the components of the method. In some embodiments. the device comprises portions comprising material of different pore size. or non-porous material, the material being contiguous with the first material and designed to receive a sample or receive or store components of the method. In some embodiments, the portions of the chromatogiaphic device are separate, contiguous or overlapping or designed to corne together in use.

In some embodiments, the sample pad is chromatographicaliy connected to a test portion of the device, the test portion comprising a binding agent such as an antibody or an antigen binding fragment thereof In some embodiments, the sample pad is chromatographicaliy connected to a test portion of the device, the test portion comprising a binding agent such as an antibody or an antigen binding fragment thereof.

In some embodiments, when chromatographicaliy active portions of the sample to be tested move from the sample pad towards and through the test portion, enzyme or liver enzyme or métabolites or ALTl is captured onto test or contiol portions (including strips) of the device and the remainder of the sample flowing from the sample pad is uncaptured. In some embodiments, the uncaptured components of the test sample are collected chromatographicaliy into an absorbent pad. which is positioned in anv orientation with respect to the test portion. Components of the subject sample, such as red blood cells or particular white blood cells may be retained in the sample pad. for example, by selecting a pad of suitable mesh or pore size and/or by the inclusion of spécifie reagents such as antibodies or lectins to bind and retain these components.

In some embodiments, once the test portion of the immunochromatographic device has been exposed to (say) ALTl in the subject sample, the method proceeds by allowing contact between a/the test portions and a détection binding agent. In some embodiments, the détection marker/s stored in a separate portion of the kit.

In some embodiments, the détection marker comprises a visually détectable reporter molécule and a positive resuit may be essentially immediately observed in the test and/or control portions of the immunochromatographic device. In other embodiments, the détection marker may be detected using further détection protocols and devices such as will be well known to those of oïdinaiy skill in the art. For example, colloïdal métal or métal oxide particles or colloïdal non-metal particles or dyes or colored latex are convenieîitly used.

Numerous labels for binding agents such as antibodies or antigen binding fragments thereof are available which can be generally grouped into categories. The binding agent can be labelled with a radioisotope using the techniques described in Current Protocols in Immunology, Volumes 1 and 2, Coligen et al., Ed. WileyInterscience, New York, N.Y., Pubs. (1991), for example, and radioactivity can be measured using scintillation counting. Fluorescent labels may be used such as rare earth chelates (europium chelates) or fluorescein and its dérivatives, rhodamine and its dérivatives, dansyl, Lissamine, phycoerythrin and Texas Red are available. The fluorescent labels can be conjugated to the binding agent using the techniques disclosed in Current Protocols in Immunology (supra). Fluorescence can be quantified using a fluorimeter. Various enzyme-substrate labels are available and U.S. Pat. No. 4,275,149 provides a review of some of these. The enzyme generally catalyzes a chemical alteration of the chromogenic substrate that can be measured using various techniques. For example, the enzyme may catalyse a colour change in a substrate, which can be measured spectrophotometrically. Alternatively, the enzyme may alter the fluorescence or chemiluminescence of the substrate.

Techniques for quantifying a change in fluorescence are described above. The chemiluminescent substrate becomes electronically excited by a chemical reaction and may then émit light that can be measured (using a chemiluminometer, for example) or donates energy to a fluorescent acceptor. Examples of enzymatic labels include luciferases (e.g., firefly luciferase and bacterial luciferase; US Patent No. 4,737,456), luciferin, 2,3-dihydrophthalazinediones, malate dehydrogenase, urease, peroxidase such as horseradish peroxidase (HRPO), alkaline phosphatase, .beta.-galactosidase, glucoamylase, lysozyme, saccharide oxidases (eg, glucose oxidase, galactose oxidase, and glucose-6-phosphate dehydrogenase), heterocyclic oxidases (such as uricase and xanthine oxidase), lactoperoxidase, microperoxidase, and the like. Techniques for conjugating enzymes to antibodies are described in O'Sullivan et al., Methods for the Préparation of Enzyme-Antibody Conjugates for use in Enzyme Immunoassay, in Methods in Enzym. (ed J. Langone and H. Van Vunakis), Academie press, New York, 73:147-166 (1981).

Examples of enzyme-substrate combinations include, for example: Horseradish peroxidase (HRPO) utilizes hydrogen peroxide to oxidize a dye precursor (e.g., orthophenylene diamine (OPD) or 3,3',5,5'-tetramethyl benzidine hydrochloride (TMB));] alkaline phosphatase (AP) with para-Nitrophenyl phosphate as chromogenic substrate; and 3) β-D-galactosidase with a chromogenic substrate (e.g., p-nitrophenyl.beta.-D-galactosidase) or fluorogenic substrate 4-methylumbelliferyl-.beta.-D19228 galactosidase. Numerous other enzyme-substrate combinations are available to those skilled in the art. For a general review of these, see US Patent Nos. 4,275,149 and 4,318,980.

Sometimes, the label is indirectly conjugated with the antibody. The skilled artisan will be aware of varions techniques for achieving this. For example, the antibody can be conjugated with biotin and any of the three broad categories of labels mentioned above can be conjugated with avidin or streptavidin , or vice versa. Biotin binds selectively to avidin and thus, the label can be conjugated with the antibody in this indirect manner. Alternatively, to achieve indirect conjugation ofthe label with the antibody, the antibody is conjugated with a small hapten (e.g., digoxin or biotin) and one ofthe different types of labels mentioned above is conjugated with an anti-hapten antibody (e.g., anti-digoxin antibody or anti-biotin antibody). Thus, indirect conjugation of the label with the antibody can be achieved. In another embodiment, the antibody need not be labeled, and the presence thereof can be detected using a labeled antibody which binds to the antibody. The binding agent may be employed in any known assay method, such as compétitive binding assays, direct and indirect sandwich assays, and immunoprécipitation assays. Zola, Monoclonal Antibodies: A Manual of Techniques, pp. 47-158 (CRC Press, Inc. 2011).

For use in the applications described or suggested herein, diagnostic assay kits or articles of manufacture are also provided. Such kits may comprise a carrier means being compartmentalized to receive in close confinement one or more container means such as vials, tubes, and the like, each of the container means comprising one of the separate éléments to be used in the method. For example, one of the container means may reporter means, such as a biotin-binding protein, such as avidin or streptavidin, bound to a reporter molécule, such as an enzymatic, florescent, or radioisotope label.

Diagnostic assay kits will typically comprise the container described above and one or more other containers comprising materials désirable from a commercial and user standpoint, including buffers, diluents, filters, needles, syringes, and package inserts with instructions for use. A label may be présent on the container to indicate that the composition is used for a spécifie therapy or non-therapeutic application, and may also indicate directions for use, such as those described above. Other optional components in the kit include one or more buffers (e.g., block buffer, wash buffer, substrate buffer, and the like), other reagents such as substrate (e.g., chromogen) which is chemically altered by an enzymatic label, epitope retrieval solution, control samples (positive and/or négative controls), control slide(s) etc.

The terms full-length antibody, or whole antibody are used interchangeably to refer to an antibody in its substantially intact form, as opposed to an antigen binding fragment of an antibody. Specifically, whole antibodies include those with heavy and light chains including a constant région. The constant région may be wild-type sequence constant régions or amino acid sequence variants thereof.

The term antigen binding protein herein includes a single polypeptide chain, (i.e., a sériés of contiguous amino acids linked by peptide bonds), or a sériés of polypeptide chains covalently or non-covalently linked to one another (i.e., a polypeptide complex) capable of binding to (say) ALTl in the manner described and/or claimed herein. For example, the sériés of polypeptide chains can be covalently linked using a suitable chemical or a disulphide bond. Examples of non-covalent bonds include hydrogen bonds, ionic bonds, Van der Waals forces, and hydrophobie interactions. A non-covalent bond contemplated by the présent disclosure is the interaction between a VH and a VL, e.g., in some forms of diabody or a triabody or a tetrabody or an Fv.

As used herein, variable région refers to the portions of the light and/or heavy chains of an antibody or of a heavy chain only antibody (e.g., camelid antibodies or cartilaginous fish immunoglobulin new antigen receptors (IgNARs)) that is capable of specifically binding to an antigen and includes amino acid sequences of complementary determining régions CDRs; i.e., CDRl, CDR2, and CDR3, and FRs. For example, the variable région comprises three or four FRs (e.g., FRI, FR2, FR3 and optionally FR4) together with three CDRs. VH refers to the variable région of the heavy chain. VL refers to the variable région ofthe light chain.

As used herein, the term Fv shall be taken to mean any protein, whether comprised of multiple polypeptides or a single polypeptide, in which a VL and a VH associate and form a complex having an antigen binding domain, i.e., capable of specifically binding to an antigen (e.g.,ALTl). The VH and the VL which form the antigen binding domain can be in a single polypeptide chain or in different polypeptide chains. This terni shall be understood to encompass fragments directly derived from an antibody as well as proteins produced using recombinant means. In some examples, the VH is not linked to a heavy chain constant domain CHl and/or the VL is not linked to a light chain constant domain (CL), e.g., a domain antibody. Exemplary Fv containing polypeptides or proteins include a Fab fragment, a Fab’ fragment, a F(ab’) fragment, a scFv, a diabody, a triabody, a tetrabody or higher order complex, or any of the foregoing linked to a constant région or domain thereof, e.g., CH2 or CH3 domain, e.g., a minibody.

A Fab fragment consists of a monovalent antigen-binding fragment of an immunoglobulin, and can be produced by digestion of a whole antibody with the enzyme papain, to yield a fragment consisting of an intact light chain and a portion of a heavy chain or can be produced using recombinant means. A Fab' fragment of an antibody can be obtained by treating a whole antibody with pepsin, followed by réduction, to yield a molécule consisting of an intact light chain and a portion of a heavy chain comprising a VH and a single constant domain. Two Fab' fragments are obtained per antibody treated in this manner. A Fab’ fragment can also be produced by recombinant means. An F(ab')2 fragment of an antibody consists of a dimer of two Fab' fragments held together by two disulfide bonds, and is obtained by treating a whole antibody molécule with the enzyme pepsin, without subséquent réduction. An Fab2 fragment is a recombinant fragment comprising two Fab fragments linked using, for example a leucine zipper or a CH3 domain. A single chain Fv or scFv is a recombinant molécule containing the variable région fragment (Fv) of an antibody in which the variable région of the light chain and the variable région of the heavy chain are covalently linked by a suitable, flexible polypeptide linker.

As used herein, the term antigen binding domain shall be taken to mean a région of an antibody that is capable of specifically binding to an antigen, i.e., a VH or a VL or a Fv or a variable région as defined herein. The antigen binding domain need not be in the context of an entire antibody, e.g., it can be in isolation (e.g., a domain antibody) or in another form, such as a scFv.

As used herein, the term binds in reference to the interaction of a protein or an antigen binding domain thereof with an antigen means that the interaction is dépendent upon the presence of a particular structure (e.g., an antigenic déterminant or epitope) on the antigen. For example, an antibody recognizes and binds to a spécifie protein structure rather than to proteins generally. If an antibody binds to epitope A, the presence of a molécule containing epitope A (or free, unlabeled A), in a reaction containing labeled A and the antibody, will reduce the amount of labeled A bound to the antibody.

As used herein, the term specifically binds or spécifie binding agent or spécifie antibody means a binding agent reacts or associâtes more frequently, more rapidly, with greater duration and/or with greater affinity with a particular antigen than it does with alternative antigens. For example, a protein that specifically binds to an antigen binds that antigen with greater affinity (e.g., 20 fold or 40 fold or 60 fold or 80 fold to 100 fold or 150 fold or 200 fold greater affinity), avidity, more readily, and/or with greater duration than it binds to other antigens, e.g., to ALT2. In some embodiments, the binding agent selectively binds the antigen which means that binding is exclusive to the specified antigen.

The description includes the following non-limiting examples to illustrate the invention.

Example 1 -Human plasma interfères strongly with the ability of a range of mouse antibodies to bind ALT

Commercially-available ELISAs for measurement of ALT in human plasma also exhibit very poor corrélation with enzymatic ALT levels, and surprisingly yield results that are highly dépendent on the sample dilution used for sérum or plasma (see Figure 1).

As shown in Figure 2, initial experiments disclosed herein by the inventor/s provided similar results. Using a range of MAbs produced in mice using the ALT1 protein as immunogen (Figure 2), the results were highly dépendent on the sample dilution used for sérum or plasma. However, the présent inventor/s reasoned that one or more factors présent in human plasma may interfère with the antigenic reactivity of

ALT with antibody, and thus preventing the development of useful assays for ALT mass concentration using this approach.

The surprising and novel observation of the strong interférence by human plasma on the level of ALT antigenic reactivity with a range of mouse MAb led the inventor/s to conclude that interfering substance(s) in plasma may bind to and obscure one or more of the antigenic epitopes in ALTl that are able to induce an immune response in mice.

Example 2- Rabbits produce robust antibodies against human ALTl

The inventor/s compared the amino acid sequence of ALTl in humans and in mice (see Figure 3A) and identified the proteins hâve high levels of identity. Accordingly, it may be expected that only certain parts of the protein surface are sufficiently different between humans (the antigen) and mice (the host animal) to be able to function as foreign antigens to induce an immune response. Furthermore, the limited number of highly antigenic sites may overlap with the sites that bind factor(s) présent in human plasma, preventing proper récognition of the ALT protein when assayed in human plasma using the antibodies directed against such sites.

The inventor/s devised a solution to this problem by taking advantage of the known fact that rabbits do not hâve a homolog of the human ALTl protein or gene, and instead hâve only a homolog of the ALT2 protein that appears to provide the relevant biochemical functions in ail forms of body tissues. Thus, substantially ail parts of the human ALTl protein (and especially the surface part of the protein) may be expected to be immunogenic in rabbits, in contrast to the situation in mice where only the limited régions of différence between mouse and human ALTl will be immunogenic.

As shown in Figure 4, rabbits produced robust antibody responses after immunization with purified human ALTL

Example 3 -Lack of interférence by human plasma in the results of Rabbit antibody ELISA

After purification of spécifie anti-ALT antibodies from the total rabbit IgG by antigen-affinity chromatography, an ELISA was established using rabbit anti-ALT to capture ALT in human plasma, and biotin-labelled rabbit anti-ALT and horseradish peroxidase-labelled streptavidin to detect the captured ALT.

As shown in Figure 5, this ELISA was not adversely affected by the presence of human serum/plasma, making it suitable for the analytical détermination of ALT mass concentration in human clinical specimens. Figure 6 illustrâtes the strategy used to couvert the ELISA format of the test into a colloïdal gold détection method suitable for latéral flow immunochromatography.

Example 4 - Détection of ALT in human plasma or whole blood in the format of a lateral-flow, immunochromatographic test strip

Using further samples of the same affmity-purified rabbit anti-ALT and the strategy illustrated in Figure 6, it was shown that it is possible to detect ALT in human plasma or whole blood in the format of a lateral-flow, immunochromatographic test strip (Figure 7).

In these examples, it is readily observed that the enzymatic level of ALT in the clinical specimens shows a visual corrélation with the intensity of the ALT test line in the POC test strips. Measurement of the ALT test line intensity using the AX-2 instrument (Figure 10) provides a numerical value for each test and allows the corrélation between test line intensity (peak height) and enzymatic ALT values to be determined (Figure 8A and 8B), showing close corrélation between the two values. This is in contrast to a lateral-flow, immunochromatographic test for ALT1 using mouse monoclonal antibodies described by Hu et al (2016), where there was very low corrélation with enzymatic ALT levels, presumably because of variable levels of interférence by plasma proteins as we hâve noted herein.

Interestingly, in our example a small number of samples demonstrate substantially elevated amounts of ALT mass concentration versus enzymatic ALT when compared to the average level of corrélation (line of best fit), which may represent patients with more advanced forms of liver disease and having elevated ALT mass concentration compared to enzymatic ALT, as reported by Kim et al (2006). Therefore the ALT test described here provides the benefit of strong corrélation with standard enzymatic ALT tests (in contrast to Hu et al [2016]), but with the additional capacity to detect elevated ALT mass concentration in patients with advanced liver disease where ALT production or activity may be compromised giving a false indication of normal (healthy) levels of ALT when measured by enzymatic activity.

Example 5 -Visual readout of normal (healthy) versus abnormal (elevated, unhealthy) levels of ALT

While the use of an instrument such as the AX-2 instrument in combination with the POC ALT test is désirable for many reasons, there is also a need for a test that can give a simple, visual readout of normal (healthy) versus abnormal (elevated, unhealthy) levels of ALT, for example < 40 IU/L, or > 40 IU/L respectively according to EASL guidelines. This is readily achieved using methods previously described in development of a latéral flow, POC test for measuring CD4 T-cells (US Patent 8,409,818 and other territories) (Figure 9). This provides the additional advantage that similar instruments, test cartridges and manufacturing methods can be used for the various test devices.

In the CD4 T-cell test, the amount of CD4 antigen represented at the test (T) line is directly proportional to the number of CD4 T-cells. The test signal is then compared visually or by instrument reader versus one or more reference Unes representing clinically relevant levels of CD4 T-cells, in the figure the example of 350 T-cells per μΐ which is recommended by WHO for prioritisation of antirétroviral therapy in HIV infection. Similarly, for ALT we will préparé a reference line corresponding to one or more clinically relevant amounts of ALT, including the 40 IU/L level recommended by EASL. A schematic of the proposed semi-quantitative ALT test is shown in Figure 10.

It will be appreciated by one skilled in the art that this test can be further modified to provide for simultaneous measurement of ALT and one or more other relevant biomarkers, for example ALT plus platelet levels which are both important markers in management of pre-eclampsia.

It will be further appreciated that this general method can be applied to the development of test assays and especially POC test assays against other enzymes, including but not limited to other liver-specific enzymes that may be used for different purposes. For example, aspartate aminotransferase (AST) may be used instead of ALT for measurement of liver disease.

In addition, the combination of ALT plus platelet levels may provide a useful non-invasive biomarker for the extent of liver fibrosis, by analogy with enzymatic AST and platelet levels where the AST-platelet ratio index (APRI) score is the arithmetic product of the sample resuit for AST (divided by normal level), multiplied by 100 and divided by the platelet count (in 10⁹ per ml). APRI score is recommended by the World Health Organisation for the non-invasive measurement of liver fibrosis where there is not access to alternative methods such as Fibroscan (specialised ultrasound). Similarly, a POC test for APRI would combine the measurement of AST levels as described herein for ALT, and platelet levels.

Example 6 -Screening for agents that bind ALT or other enzymes

While the ALT assays described herein hâve made use of affinity-purified polyclonal antibodies produced in rabbits, it will be understood that monoclonal antibodies or other binding agents may be preferred for this purpose. Techniques for the production of rabbit monoclonal antibodies are now available, and it is expected that rabbit MAbs against ALTl could be readily obtained due to the lack of endogenous ALTl in the rabbit. However in mice, the species most commonly used for production of MAbs, the presence of endogenous ALTl results in most MAbs being directed against epitopes that may be susceptible to blocking by factor(s) présent in human plasma, and this is likely to be true also in rats that also express ALTl very similar to human (Figure 3B). However the assays described herein for measurement of ALTl and especially the ELISA assays allowed us to develop a novel assay for the screening and sélection of antibodies and especially MAbs that are not susceptible to such plasma blocking and inhibition, and thus suitable for use in clinical assays such as the ALT assays described here.

As shown in Figure 11 A, when purified recombinant ALT is coated on an ELISA plate followed by sequential addition of human plasma (or no plasma as control) and a suitable dilution of the antibody or MAb of interest, the level of inhibition caused by addition of plasma can be determined, and antibody préparations or MAbs that are not substantially inhibited can be identified as a resuit. It will be appreciated by one skilled in the art that the same technique could be applied to antibodies produced in any animal species or by recombinant means, and also to nonantibody binding agents such as peptide ligands identified by phage display and other methods, or nucleic acid binding ligands (aptamers) identified by various methods.

Example 7 -Specificity of the assay for the liver-specific ALTl isoform

As described above, in humans the ALTl isoform is predominantly expressed in the liver whereas the ALT2 isoform is predominantly expressed in muscle and other tissues, thus an assay that is spécifie for ALTl versus ALT2 is expected to hâve more clinical utility for détection and monitoring of liver disease.

As shown in Figure 12, when unpurified human ALTl or human ALT2 (Seq ID: 6) representing équivalent levels of enzymatic ALT activity are coated on ELISA plates followed by rabbit antibodies against ALTl, ELISA reactivity is only seen for ALTl and not ALT2 for ail concentrations of enzymatic ALT, demonstrating specificity of the reagent and the assay for ALTl and not ALT2.

Similarly in Figure 13, when unpurified human ALTl or human ALT2 (Seq ID: 6) representing équivalent levels of enzymatic ALT activity are subjected to the immunochromatographic assay as in Figure 7 (Example 4), only ALTl is detected in the immunochromatographic test.

Many modifications will be apparent to the skilled addressee without departing from the scope of the invention.

BIBLIOGRAPHY

Younossi ZM, Koenig AB, Abdelatif D, Fazel Y, Henry L, Wymer M. 2016._Global epidemiology of nonalcoholic fatty liver disease - Meta-analytic assessment of prevalence, incidence, and outcomes. Hepatology 64(1):73-84.

European Association for the Study of the Liver. 2012. EASL Clinical Practice Guidelines: management of chronic hepatitis B virus infection. JHepatol. 57:167—185.

Pollock NR, Rolland JP, Kumar S, Beattie PD, Jain S, Noubary F, Wong VL, Pohlmann RA, Ryan US, Whitesides GM. 2012. A Paper-Based Multiplexed Transaminase Test for Low-Cost, Point-of-Care Liver Function Testing. Science Translational Medicine 4, 152ral29.

Kim HJ, Oh SW, Kim DJ, Choi EY. 2009. Abundance of Immunologically Active Alanine Aminotransferase in Sera of Liver Cirrhosis and Hepatocellular Carcinoma Patients. Clinical Chemistry 55:5, 1022-1025.

Hu X, Cheng S, Liu X, Li J, Zheng W, Lu G, Zhang J, Zheng J, Zhang J. 2015. Development of monoclonal antibodies and immunochromatographic latéral flow device for rapid test of alanine aminotransferase isoenzyme I. Protein Expression and Purification 119:94-101.

Hassan et.al. A microfluidic biochip for complété blood cell counts at the point of care. Technology 3, 201-213 (2015).19.

Claims (13)

CLAIMS:

1. An immunoassay suitable for point of care to assess liver disease or function, said assay comprising:

(i) contacting a blood sample from a human subject with a spécifie binding agent that recognizes an epitope of ALTl, that is not recognized by rodent antibodies when the rodent antibodies are in the presence of human plasma, to form an antigenbinding agent complex and detecting the complex using a second or further binding agent linked to or comprising a détectable reporter; and (ii) detecting liver disease or liver function in the subject contingent upon the mass concentration of ALTl in the sample.

2. The assay of claim l wherein the spécifie binding agent is a lagomorph antibody or comprises an antigen binding part thereof, or wherein the spécifie binding agent recognizes the same epitope as the rabbit antibody.

3. The assay of claim l or 2 wherein the mass concentration of the ALTl is positively correlated with ALTl enzymatic activity.

4. The assay of any one of claims l to 3 wherein the mass concentration of ALTl is positively correlated with increasing liver disease.

5 22. The assay of any one of daims l to 9 or 16 to 21 or the method of claim 12 or

5. The assay of any one of claims l to 4 wherein the binding agent is an antibody or comprises an immunoglobulin domain thereof.

6. The assay of one of claim l to 5 wherein the assay is an enzyme-linked immunosorbent (ELISA)-type or immunochromatographic-type assay or microfluidic assay and the binding agent is immobilised on a support.

7. The assay of claim 6, wherein the assay is an immunochromatographic-type assay and wherein the blood sample is contacted with the binding agent by applying the blood sample to a sample portion of an immunochromatographic device wherein the device sample portion is operably connected to a spaced capture portion of the device and whereby the components of the sample flow from the device sample portion to and through the device capture portion, and wherein one capture portion comprises the binding agent which specifically binds to the antigen in the sample such that the antigen is captured by the binding agent to form a binding agent-antigen complex in the capture portion.

8. The assay of any one of daims l to 7 wherein the antigen complex is detected using a binding agent such as an antibody or antigen-binding fragment, ligand or affimer that specifically binds the antigen and directly or indirectly provide a détectable signal that can be quantified visually or by instrument reader.

9. The assay of any one of daims 7-8 wherein the capture portion is a test line.

10. A kit for measuring the mass concentration of ALTl comprising (i) a chromatographie device comprising a porous membrane, or a microfluidic device, operably connected to a sample portion, one or more capture (test) portions, and optionally one or more of the following; a conjugate (détection marker) portion, a sticker component, a suitable control portion and optionally a cell lysis or solubilisation portion, and (ii) a lagomorph antibody or an agent comprising the antigen binding part thereof that recognizes an epitope of ALTl, and forms an ALTl-lagomorph antibody/binding part complex, and (iii) optionally instructions for using the device to détermine liver function.

11. The kit of daim 10 wherein the device is chromatographie device comprising a porous membrane suitable for reverse or latéral flow immunochromatographic formats.

12. A kit for measuring the mass concentration of ALTl comprising (i) a chromatographie device comprising a porous membrane, or a microfluidic device, operably connected to a sample portion, one or more capture (test) portions, and optionally one or more of the following; a conjugate (détection marker) portion, a sticker component, a suitable control portion and optionally a cell lysis or solubilisation portion, and (ii) a lagomorph antibody or an agent comprising the antigen binding part thereof that recognizes an epitope of ALTl, and forms an ALTl-lagomorph antibody/binding part complex, and (iii) optionally instructions for using the device to détermine liver function.

13. The method of claim 12, wherein the method is able to detect a mass concentration of human ALTl that is équivalent to 40 IU/L ALTl or équivalent to between 20 and 200 IU/L ALTL

14. A method of screening for antibody or other spécifie binding agents that are substantially not inhibited from antigen binding by plasma, the method comprising contacting antigen and a potential antigen binding agent in the presence of different concentrations of plasma to détermine whether the binding agent can bind the antigen in the presence of plasma.

15. The method of claim 14, wherein the antigen is a liver enzyme such as ALTl.

16. An immunoassay suitable for point of care to assess liver disease or liver function, said assay comprising:

(i) contacting a blood sample from a human subject with a spécifie binding agent that recognizes an epitope of a liver enzyme or a métabolite thereof, that is not recognized by rodent/mouse antibodies when the rodent antibodies are in the presence of human plasma, to form an antigen-binding agent complex and detecting the complex using a second binding agent linked to a détectable reporter; and (ii) detecting liver disease or function in the subject contingent upon the mass concentration of liver enzyme or métabolite thereof in the sample.

17. The assay of claim 16 wherein the spécifie binding agent is a lagomorph antibody or comprises an antigen binding part thereof, or wherein the spécifie binding agent recognizes the same epitope as the lagomorph antibody.

18. The assay of claim 16 or 17 wherein the mass concentration of the liver enzyme is positively correlated with the liver enzyme enzymatic activity.

19. The assay of any one of daims 16 to 18 wherein the mass concentration of liver enzyme is positively correlated with increasing liver disease.

20. The assay of any one of daims 16 to I9 wherein the binding agent is an antibody or comprises an immunoglobulin domain thereof.

21. The assay of one of claim 16 to 20 wherein the assay is an enzyme-linked immunosorbent (ELISA)-type or immunochromatographic-type assay, or microfluidic assay and the binding agent is immobilised on a support.

13 or the kit of claim I0 or 11 wherein the assay or method or kit further comprises assessing or includes reagents for assessing platelet levels to détermine a liver enzyme:platelet ratio index as described herein as a measure of liver fibrosis in the subject.