WO2000076587A1

WO2000076587A1 - Antibody-based treatment for streptococcus pneumoniae infection

Info

Publication number: WO2000076587A1
Application number: PCT/US2000/016581
Authority: WO
Inventors: Gary S. Nabors; David Briles
Original assignee: Aventis Pasteur SA; UAB Research Foundation
Current assignee: Sanofi Pasteur SA; UAB Research Foundation
Priority date: 1999-06-16
Filing date: 2000-06-16
Publication date: 2000-12-21
Anticipated expiration: 2001-12-16
Also published as: EP1194187A1; JP2003525208A; AU5493500A; CA2377431A1

Abstract

The present invention comprises a method of treating a mammal infected with Streptococcus pneumoniae, which methods comprises administering to the mammal a therapeutically effective amount of one or more PspA antibodies. Preferably the mammal is a human.

Description

ANTIBODY-BASED TREATMENT FOR STREPTOCOCCUS PNEUMONIAE INFECTION

BACKGROUND OF THE INVENTION

This application claims the benefit of U.S. Provisional Application No. 60/139,524, filed June 16, 1999. Field of the Invention

The present invention relates to the therapeutic use of PspA antibodies for the treatment of Streptococcus pneumoniae infection in mammals, particularly in a human. Summary of the Related Art Streptococcus pneumoniae is an important cause of otitis media, meningitis, bacteremia and pneumonia, and a leading cause of fatal infections in the elderly and persons with underlying medical conditions, such as pulmonary disease, liver disease, alcoholism, sickle cell, cerebrospinal fluid leaks, acquired immune deficiency syndrome (AIDS), and patients undergoing immunosuppressive therapy. It is also a leading cause of morbidity in young children. Pneumococcal infections (i.e. infections caused by Streptococcus pneumoniae) cause approximately 40,000 deaths in the U.S. yearly. The most severe pneumococcal infections involve invasive meningitis and bacteremia infections, of which there are 3,000 and 50,000 cases annually, respectively.

Despite the use of antibiotics and vaccines, the prevalence of pneumococcal infections has declined little over the last twenty-five years; the case-fatality rate for bacteremia is reported to be 15-20% in the general population, 30-40% in the elderly, and 36% in inner-city African Americans. Less severe forms of pneumococcal disease are pneumonia, of which there are 500,000 cases annually in the U.S., and otitis media in children, of which there are an estimated 7,000,000 cases annually in the U.S. caused by pneumococci. Strains of drug- resistant S. pneumoniae are becoming ever more common in the U.S. and worldwide. In some areas, as many as 30% of pneumococcal isolates are resistant to penicillin. The increase in antimicrobial resistant pneumococci further emphasizes the need for either preventing pneumococcal infections or developing a therapeutic regimen to cure those already infected.

Historically, antisera prepared in animals to the pneumococcal capsule was used therapeutically to treat bacteremic/septic pneumonia. Since virtually all fatal pneumonia is due to bacteremic/septic pneumonia, the procedure was of an significant medical value especially in the pre-antibiotic era. Treatment with antisera in combination with good nursing care served to decrease the death rate among patients infected with Streptococcus pneumoniae. At that time antibodies were prepared in rabbits or horses to whole killed bacteria of each capsular type. Different capsular polysaccharide types differentially facilitate virulence in humans and other species. Historically, the capsular type of the infecting patient was determined by the Quellung reaction or a mouse protection test and then an antiserum to the appropriate capsular polysaccharide type was given to the patient parenterally. These treatments were published prior to the wide spread use of antibiotics (White, B. 1938. The Biology of Pneumococcus. The Commonwealth Fund, New York; Heffron, R. 1939. Pneumonia. The Commonwealth Fund, New York). Using these methods, it was necessary for the attending physician to know the polysaccharide type of the pneumococcus prior to administering a specific antiserum, since antisera to most specific capsule types are not cross- reactive.

Protection mediated by anti-capsular polysaccharide antibody responses are capsular type specific. Different polysaccharide types differentially facilitate virulence in humans and other species. In total, there are at least 90 different capsular polysaccharide types of S. pneumoniae that cause disease in man (Heinrichsen, J. Six newly recognized types of Streptococcus pneumoniae J. Clin. Micro. 33: 2759-62 (1995)). The 23 most common capsular types represent about 90% of the pneumococcal disease in adults. These 23 polysaccharide types have been used in a licensed pneumococcal vaccine since 1983 (D.S. Fedson, M. Musher, Vaccines, S.A. Plotkin and J.E.A. Montimer, eds., 1994, pp. 517-564). The efficacy of the vaccine has been controversial, and at times the justification for the recommended use of the vaccine questioned. It has been speculated that the efficacy of this vaccine is negatively affected by having to combine 23 different antigens. Having a large number of antigens combined in a single formulation may negatively affect the antibody responses to individual types within this mixture because of antigenic competition. The efficacy is also affected by the fact that the 23 serotypes do not encompass all serological types associated with human infections and carriage. Consequently, a therapeutic antibody- based treatment for infections with S. pneumoniae which uses antibodies to capsular polysaccharide is problematic in that it is not possible to cover all the strains that are infectious in man.

Therefore, there exists a need for a therapeutic treatment for S. pneumoniae that is simple, efficacious for all infectious S. pneumoniae strains, and is not limited by antibiotic resistance.

McDaniel et al. described in 1984 an immunogenic, species-common protein from S. pneumoniae, designated pneumococcal surface protein A (McDaniel LS, G Scott, JF Kearney, DE Briles. Monoclonal antibodies against protease sensitive pneumococcal antigens can protect mice from fatal infection with Streptococcus pneumoniae. J. Exp. Med. 160:386-397, 1984). The term "PspA" was first used in a title of a paper published in 1987 (McDaniel LS, J Yother, L Vijayakumar, M McGarry, WR Guild, DE Briles. Use of insertional inactivation to facilitate studies of biological properties of pneumococcal surface protein A (PspA). J. Exp. Med. 165:381-394, 1987); see also U.S. patent nos. 5,728,387 and 5,679,768.

PspA from S. pneumoniae contains choline-binding repeats that are responsible for the attachment of the PspA to the surface of the pneumococcus. PspA molecules interfere with complement activation, slow clearance of pneumococci from the blood of infected mice and elicit protection against pneumococcal sepsis, otitis media, and nasal carriage. Although variable, antibody responses raised to PspA are cross-reactive to heterologous PspA proteins and immunization with one PspA can protect against pneumococci that contain a heterologous PspA and capsule type (Crain et al. Pneumococcal surface protein A (PspA) is serologically highly variable and is expressed by all clinically important capsular serotypes of Streptococcus pneumoniae Infect. Immun. 58: 3293-99 (1990)). Such cross-protective immunity has been shown using truncated PspA proteins of various lengths (McDaniel et al. , Location of protection-eliciting epitopes on PspA of Streptococcus pneumoniae between amino acid residues 192 and 260; Microb. Pathogen 17: 323-37 (1994)). A protective region spanning amino acids 192-270 has been used as the basis for organizing PspA proteins into three families further subdivided into six clades (Briles et al, PspA and PspC: their potential for use as pneumococcal vaccines; Microb. Drug Resist. 3: 401-08 (1997); see also U.S. 5,955,089). PspA family 1 is composed of clades 1 and 2, family 2 is composed of clades 3-5 and family 3 includes only clade 6. Clade 6 is most dissimilar from all other clades. Over 97% of the PspA molecules typed to date have been found to be members of families 1 and 2. Furthermore, PspA shows cross-reactivity with the related S. pneumoniae antigen, PspC.

SUMMARY OF THE INVENTION

The present invention comprises a method of treating a mammal infected with Streptococcus pneumoniae, which method comprises administering to the mammal a therapeutically effective amount of one or more PspA antibodies. Preferably the mammal is a human. In another aspect, the present invention comprises the use of PspA antibodies in the manufacture of a medicament for the treatment of Streptococcus pneumoniae infection in a mammal (preferably a human).

Due to the cross-reactive nature of anti-PspA antibodies, the method of the invention is independent of the specific polysaccharide type of the infectious S. pneumoniae strain. Therefore, unlike the prior art, the present invention obviates the need both to type the S. pneumoniae as well as the need to use tens of different antigens from various S. pneumoniae strains to produce antibodies that cover the spectrum of different infectious S. pneumoniae strains. The method of the present invention provides a less complex approach to treatment and leads to reduced delay in patient treatment.

Until now it was unknown whether S. pneumoniae expressed PspA during infection and, therefore, it was uncertain whether passive anti-PspA antibody treatment would be effective against an existing infection; without expression, treatment with anti-PspA antibodies clearly would be ineffective. We have discovered that S. pneumoniae does in fact express PspA during infection. Furthermore, it was uncertain whether sufficient amount of antibody could be delivered to the multiple foci of bacterial infection to effectively treat it. As demonstrated below, we have found that despite the uncertainties inherent in the prior art, passive anti-PspA antibody treatment is effective against S. pneumoniae infection.

The foregoing merely summarizes certain aspects of the invention and is not meant to limit the invention in any manner. All patents and other publications recited in this specification are hereby incorporated by reference in their entirety.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention comprises the use of PspA antibody as a therapeutic against S. pneumoniae infection in a mammal (preferably human). The antibodies for use in the present invention can be generated by immunizing humans or animals with one or more PspA molecules. Immunoglobulin for therapeutic use could be purified from plasma using the standard Cohn-Oncley method (Cohn EJ, Strong LE, Hughes WI Jr, et al. Preparation and properties of serum and plasma proteins. IV: A system for the separation into fractions of protein and lipoprotein components of biological tissues and fluids. J Am Chem Soc 1946;68:459-75. Oncley JL, Melin M, Richert DA, Cameron JW, Gross PM Jr. The separation of the antibodies isoagglutinins, prothrombin, plasmonogen and beta-lipoprotein into sub-fractions of human plasma. J Am Chem Soc 1949;71 :541-50) or a modification of this method. As described in the Background of the Invention, there are numerous strains of S. pneumoniae. In a preferred embodiment of the present invention, more than one PspA molecule from different strains of S. pneumoniae is utilized in the production of PspA antibodies. In a more preferred embodiment of the present invention, PspA proteins from three to five different S. pneumoniae strains (preferably from different clades) is used to generate PspA antibodies. In another preferred embodiment of the present invention, PspA proteins from clades 2, 3, and 4 are used to generate PspA antibodies. In another preferred embodiment of the present invention, PspA proteins from clades 1 , 2, 3, 4 and 6 are used to generate PspA antibodies. In a particularly preferred embodiment of the present invention PspA proteins containing truncated forms of PspA proteins from clades 1, 2, 3, 4 and 6 are used to generate PspA antibodies. As noted, antibodies raised against PspA (or one or more of its fragments) from one or more different strains and/or clades are administered to a subject (preferably human) infected with S. pneumoniae.

In an alternate embodiment of the present invention, the antibody preparation is made from the serum of non-immunized individuals with naturally high titers of anti-PspA antibody.

The term "PspA" refers to pneumococcal surface protein A and fragments thereof including but not limited to PspNRxl. The term PspA includes but is not limited to mutant proteins of naturally occurring PspA that retain at least one epitope of the naturally occurring PspA, such as PspNRxlMI. A number of U.S. patents disclose various PspA fragments.

E.g., U.S. patent nos. 5,980,909, 5,965,141, 5,871,943, 5,856,170, and 5,804,193.

The term PspNRxl refers to a protein that is Ν-terminal region (aal-314) of the naturally occurring PspA polypeptide of Rxl (GenBank Accession No. M74122 and WO 92/14488). The S. pneumoniae strain Rxl has been deposited with the American Type Culture Collection, 12301 Parklawn Drive, Rockville, Md. 20852 under accession no. 55834. The term PspNRxlMI refers to a protein that is the Ν-terminal region (aal-314) of the naturally occurring PspA polypeptide of Rxl in which amino acid 96 has been changed from a methionine to an isoleucine.

The terms "PspA antibody" and "anti-PspA antibody" refer to any antibody or group of antibodies to PspA, PspNRxl, or PspNRxlMI, as defined above. PspA antibodies include but are not limited to polyclonal antibodies to PspA, monoclonal antibodies to PspA, monospecific polyclonal antibodies to PspA, and mixtures thereof. The phrase "therapeutically effective amount" as used herein means an amount of PspA antibody sufficient to eliminate (preferably) an S. pneumoniae infection in the treated mammal, or halt or reduce the rate of growth of bacterial burden in the infected mammal.

The PspA antibodies for use in the present invention, used as a therapeutic agent, can be delivered in the form of an antiserum, an IgG fraction from an antiserum, or as a pooled

IgG + IgM fraction from an antiserum. Additionally, the PspA antibodies of the present invention could be purified from antiserum by purification techniques, many of which are well known in the art, such as immunoaffinity columns.

In another embodiment of the present invention, administration of PspA antibody is combined with administration of antibiotics or other antibodies to S. pneumoniae antigens.

Such therapeutic use of the PspA antibodies is anticipated to improve the recovery time of the patient, or his/her likelihood of survival. It is envisioned that therapy with the invention would be unlikely to inhibit the activity of antibiotics when both agents are co-administered.

The present invention has a distinct advantage over other conceivable similar substances, such as a polyvalent anti-pneumococcal polysaccharide serum, because of the high level of cross-reactivity in the anti-PspA humoral response. Due to the cross-reactive nature of anti-PspA antibodies, the specific polysaccharide or PspA type of the infectious S. pneumoniae strain would not limit the usefulness of the invention. Therefore, unlike the prior art, in the present invention there is no need to type the S. pneumoniae, and, thus, methods of the present invention are less complex and lead to reduced delay in patient treatment.

The amount of PspA antibody to be administered to a mammal infected with Streptococcus pneumoniae and the regime of administration can be determined in accordance with standard techniques well known to those of ordinary skill in the pharmaceutical and veterinary arts taking into consideration such factors as the particular antigen, the adjuvant (if present), the age, sex, weight, species and condition of the particular animal or patient, and the route of administration. In the present invention, the amount of specific antibody administered to provide an efficacious therapeutic dose for treatment of S. pneumoniae can be from between about 0.02 mg to about 5 mg per kg body weight. In a preferred composition and method of the present invention the dosage is between about 0.1 mg to 3 mg per kg of body weight. The optimal dosage will depend upon the post-infection time of administration. For example, an efficacious dosage will require less antibody if the post-infection time elapsed is less since there is less time for the bacteria to proliferate. In like manner an efficacious dosage will depend on the bacterial load at the time of diagnosis. Multiple injections administered over a period of days could be considered for therapeutic usage.

Examples of compositions of the invention include liquid preparations for orifice, e.g., oral, nasal, anal, vaginal, peroral, intragastric, mucosal (e.g., perlingual, alveolar, gingival, olfactory or respiratory mucosa) etc., administration such as suspensions, syrups or elixirs; and, preparations for parenteral, subcutaneous, intradermal, intramuscular, intraperitoneal or intravenous administration (e.g., injectable administration), such as sterile suspensions or emulsions. Intravenous and parenteral administration are preferred. Such compositions may be in admixture with a suitable carrier, diluent, or excipient such as sterile water, physiological saline, glucose or the like. The compositions can also be lyophilized. The compositions can contain auxiliary substances such as wetting or emulsifying agents, pH buffering agents, gelling or viscosity enhancing additives, preservatives, flavoring agents, colors, and the like, depending upon the route of administration and the preparation desired. Standard texts, such as "REMINGTON'S PHARMACEUTICAL SCIENCE", 17th edition, 1985, incorporated herein by reference, may be consulted to prepare suitable preparations, without undue experimentation.

Compositions of the invention are conveniently provided as liquid preparations, e.g., isotonic aqueous solutions, suspensions, emulsions or viscous compositions that may be buffered to a selected pH. If digestive tract absorption is preferred, compositions of the invention can be in the "solid" form of pills, tablets, capsules, caplets and the like, including "solid" preparations which are time-released or which have a liquid filling, e.g., gelatin covered liquid, whereby the gelatin is dissolved in the stomach for delivery to the gut. If nasal or respiratory (mucosal) administration is desired, compositions may be in a form and dispensed by a squeeze spray dispenser, pump dispenser or aerosol dispenser. Aerosols are usually under pressure by means of a hydrocarbon. Pump dispensers can preferably dispense a metered dose or a dose having a particular particle size.

Liquid preparations are normally easier to prepare than gels, other viscous compositions, and solid compositions. Additionally, liquid compositions are somewhat more convenient to administer, especially by injection or orally, to animals, children, particularly small children, and others who may have difficulty swallowing a pill, tablet, capsule or the like, or in multi-dose situations. Viscous compositions, on the other hand, can be formulated within the appropriate viscosity range to provide longer contact periods with mucosa, such as the lining of the stomach or nasal mucosa. Obviously, the choice of suitable carriers and other additives will depend on the exact route of administration and the nature of the particular dosage form, e.g., liquid dosage form

(e.g., whether the composition is to be formulated into a solution, a suspension, gel or another liquid form), or solid dosage form (e.g., whether the composition is to be formulated into a pill, tablet, capsule, caplet, time release form or liquid-filled form).

Solutions, suspensions and gels, normally contain a major amount of water (preferably purified water) in addition to the active ingredient. Minor amounts of other ingredients such as pH adjusters (e.g., a base such as NaOH), emulsifiers or dispersing agents, buffering agents, preservatives, wetting agents, jelling agents, (e.g., methylcellulose), colors and/or flavors may also be present. The compositions can be isotonic, i.e., it can have the same osmotic pressure as blood and lacrimal fluid.

The desired isotonicity of the compositions of this invention may be accomplished using sodium chloride, or other pharmaceutically acceptable agents such as dextrose, boric acid, sodium tartrate, propylene glycol or other inorganic or organic solutes. Sodium chloride is preferred particularly for buffers containing sodium ions.

Viscosity of the compositions may be maintained at the selected level using a pharmaceutically acceptable thickening agent. Methylcellulose is preferred because it is readily and economically available and is easy to work with. Other suitable thickening agents include, for example, xanthan gum, carboxymethyl cellulose, hydroxypropyl cellulose, carbomer, and the like. The preferred concentration of the thickener will depend upon the agent selected. The important point is to use an amount that will achieve the selected viscosity. Viscous compositions are normally prepared from solutions by the addition of such thickening agents.

A pharmaceutically acceptable preservative can be employed to increase the shelf-life of the compositions. Benzyl alcohol may be suitable, although a variety of preservatives including, for example, parabens, thimerosal, chlorobutanol, or benzalkonium chloride may also be employed. A suitable concentration of the preservative will be from 0.02% to 2% based on the total weight although there may be appreciable variation depending upon the agent selected. Those skilled in the art will recognize that the components of the compositions must be selected to be chemically inert with respect to the PspA antibodies. EXAMPLES Example 1

Production ofPspA/RxlMI

The production of PspA/Rxl is described in Nabors et al, Vaccine 18: 1743-1754 (2000). See, also, WO 99/14333 for the production of PspNRXlMI. In general, cells transformed with a plasmid containing the DΝA encoding the first 314 amino acids of PspA from Rxl were grown to mid-exponential phase and induced with 0.5 mM mM IPTG (Sigma,

Inc.). Cells were harvested approximately 2 hours after induction by centrifugation. Cell pellets were resuspended in a PBS-lysozyme lysis buffer (0.5 mg/ml lysozyme in PBS). The cells were lysed by freeze thaw and the lysate was centrifuged.

The supernatant was decanted and adjusted to 70% ammonium sulfate (J.T. Baker) to precipitate proteins. This solution was centrifuged and the supernatant was discarded. The pellet was resuspended in 30% ammonium sulfate and centrifuged. The supernatant was extensively dialyzed with a buffer consisting of 100 mM sodium acetate, 10 mM ΝaCl, pH 4.5. The dialysate was centrifuged and the supernatant was applied to a Q Sepharose Fast Flow (Pharmacia Biotech) column. The column flow through and wash were collected and dialyzed against 50 mM Tris, 2 mM EDTA, 10 mM ΝaCl, pH 7.5. The dialysate was centrifuged and the supernatant was applied to a Q Sepharose Fast Flow column. The column was washed with 50 mM Tris, 2 mM EDTA, 100 mM ΝaCl, pH 7.5, then RxlMIwas eluted with 50 mM Tris, 2 mM EDTA, 200 mM ΝaCl, pH 7.5. This eluate was analyzed by SDS- PAGE; proteins were visualized by Coomassie Blue staining and PspA products were identified by Western immunoblot analysis with monoclonal anti-PspA.

The process described in Νabors et al. (Vaccine 18), WO 99/14333, and in this example can be used (and routinely modified as needed) to express and purify essentially any PspA protein.

Example 2

Production of PspA Antibody 420 BALB/c female mice (21 groups of 20 mice) age 7-8 weeks were interperitoneally (i.p.) injected with 0.5 ml of 25 mM Tris buffered saline containing 520 μg/ml Alhydrogel and the concentration of PspNRxlMI listed below:

Table 1

After 35 days all mice were bleed via the brachial artery. 100 μl of blood from each mouse in groups 12-17 were pooled and sterile filtered (0.45 μm). The filtrate was separated into 24 - 0.5 ml aliquots each containing 433.7 μg/ml of PspA antibody as measured by ELISA.

Example 3

Therapeutic Administration of Pooled PspA Antibody : Strain WU2 30 BALB/c female mice (3 groups of 10 mice) age 7-8 weeks were infected with 300 CFU of S. pneumoniae WU2 (capsule type 3, PspA clade 2). Group 1 mice were bled six hours after infection with WU2 to assess blood CFU levels, and were then injected i.p. with 1.302 μg PspA antibody derived from Example 2. Group 2 mice were bled twelve hours after infection with WU2 and then injected i.p. with 1.302 μg PspA antibody derived from Example 2. Group 3 mice were bled twelve hours after infection with WU2 and then injected i.p. with Ringer's lactate solution. All mice were then bled 24 h after the first bleed (30 h for group 1 and 36 h for groups 2 and 3). A second dose of PspA antibody (1.302 μg) was administered i.p. 48 hours after the first administration, 54 and 60 h for groups 1 and 2, respectively. The results of the study are listed below: Table 2

Example 4

Therapeutic Administration of Pooled PspA Antibody: Capsule Types 3, 4, 5, and 6B 80 mice (CBA/N mice from Jackson Labs) were divided into four groups of 20 each. The mice in each group were infected i.v. with S. pneumoniae as follows:

Group 1 2.7 x 10⁴ CFU/mouse of DBL5 (capsule type 5/PspA clade 2); Group 2 840 CFU/mouse of EP5668 (capsule type 4/PspA clade 4); Group 3 1 16 CFU/mouse of BG7322 (capsule type 6B/PspA clade 2); and Group 4 -1000 CFU/mouse of 3JYA4 (capsule type 3/PspA clade 3). Within each group, the mice were further divided into four subgroups of five mice each as follows:

1. Mice receiving passive antibody before infection and no further treatment; 2. Mice receiving passive NMS (normal mouse serum, 1/10 dilution) before infection and no further treatment;

3. Mice infected and treated at 6, 12, and 30 hours with antibody; and 4. Mice infected and treated at 6, 12, and 30 hours with NMS. All mice were bled for CFU counts at 6 hours after infection. The mice to receive antibody or NMS post-infection were treated with 100 μl of 1/10 dilution of serum in Ringer's lactate. This process was repeated at 12 and 30 hours post-infection. The results are summarized in Table 4:

Table 3

The data for Group 3 demonstrate that treatment of S pneumoniae infected mice significantly increased the life span of infected mice and reduced the bacterial burden relative to mice administered NMS. Mice in groups 1, 2, and 4 treated with PspA antibody did not manifest increased life span or reduced bacterial burden. In each of groups 1, 2, and 4, however, not even passive immunization before infection (when bacterial load is at a minimum) was effective, indicating that groups 1, 2, and 4 are examples in which the amount or specificity of anti-PspA delivered to the infected animals was insufficient for the bacterial burden delivered and, thus, did not constitute a therapeutically effective dose of PspA antibody.

Example 5

Therapeutic Administration of Pooled PspA Antibody In this example, 42 CBA/N mice were divided into 6 groups of 7 animals:

1. Those infected with A66.1 and treated with PspA antibody at 6 hours and 54 hours post-infection

2. Those infected with A66.1 and treated with PspA antibody at 12 hours and 60 hours post-infection

3. Those infected with BG7322 and treated with PspA antibody at 24 hours and 72 hours post-infection 4. Those infected with BG7322 and treated with PspA antibody at 48 hours and 96 hours post-infection

5. Those infected with A66.1 and treated with Ringer's lactate

6. Those infected with BG7322 and treated with Ringer's lactate

All mice were be bled for CFU counts prior to each treatment. All treated mice received 0.1 ml of a 1/100 dilution of the immune serum described in Example 2. The data are give in Tables 5 and 6.

Table 4

ND = not determined

Table 5

N/A = not applicable In this example, strain A66.1 (capsule type 3, PspA clade 2) and BG7322 (capsule type 6B, PspA clade 2) were used to establish infections prior to administration of antiserum. It was of note that significant survivorship or extension of life occurred in antibody-treated mice previously infected with strain A66.1. While it was possible to demonstrate a curative effect of the anti-PspA serum for strain A66.1 in Example 6, no benefit of treatment with specific anti-PspA antibody was observed for stain BG7322. However, as in the case of Example 5, this would be an example in which the amount or specificity of anti-PspA delivered to the infected animals was insufficient for the infectious dose administered. In this case, the infectious dose of BG7322 was 2216 CFU, almost 20-fold higher than that which was used in Example 5.

Example 6

Therapeutic effect of treatment with monoclonal antibody to PspA Methods CBA/N mice were infected with 148 CFU of A66.1 (capsule type 3, PspA clade 2) and were subsequently treated at the indicated times below with 10 μg or 20 μg of XiR278 (IgGl monoclonal anti-PspA described in Crain MJ, Waltman WD, Turner JS, Yother J, Talkington DF, McDaniel LS, Gray BM and Briles DE. Pneumococcal surface protein A (PspA) is serologically highly variable and is expressed by all clinically important capsular serotypes of Streptococcus pneumoniae. Infect Immun 1990;58:3293-3299). Five to eight mice per group were used. The results are give below. Table 6

n.s. = not significant We concluded from this study that therapy with monoclonal anti-PspA antibody could cause the resolution of an established, otherwise fatal pneumococcal infection in mice. In this example, more dramatic results were observed when antibody was administered shortly (1 h) after infection, as opposed to later. However, a significant delay in the time to death was observed when 20 μg of antibody was administered at 6-12 h post-infection.

The foregoing descriptions of the various embodiments of the invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise form disclosed, and many obvious modifications and variations by those skilled in the art are possible in light of the above teaching.

Claims

We Claim:

1. A method of treating a mammal infected with S. pneumoniae, the method comprising administering to the mammal a therapeutically effective amount of one or a plurality of PspA antibodies.

2. The method according to claim 1 wherein the mammal is a human.

3. The method according to claim 1 wherein one antibody is administered.

4. The method according to claim 1 wherein a plurality of antibodies raised against PspA from three to five strains of S. pneumoniae is administered.

5. The method according to claim 4 wherein the PspA are from a plurality of clades.

6. The method according to claim 5 wherein the PspA are from clades 2, 3, and 4.

7. The method according to claim 5 wherein the PspA are from clades 1, 2, 3, 4 and 6.

8. The method according to claim 1 wherein at least a PspA antibody raised against PspNRxl is administered.

9. The method according to claim 1 wherein at least a PspA antibody raised against PspNRxlMI is administered.

10. The method according to claim 1 wherein the antibody or antibodies are co- administered with an antibiotic or an antibody to a S. pneumoniae antigen other than PspA.