Antibodies for the treatment of clostridium difficile-associated infection and disease

Abstract

Provided herein are reagents, compositions, and therapies with which to treat Clostridium difficile infection and related disease conditions and pathologies, such as Clostridium difficile -associated diarrhea, resulting from infection by Clostridium difficile bacteria and the enterotoxins produced by these bacteria. In particular, antibodies or antigen-binding fragments thereof that bind specifically to toxin A and/or toxin B of C difficile and neutralize the activities of these toxins; compositions comprising such antibodies; and methods of using the antibodies and the compositions are provided.

1 . An isolated antibody or an antigen-binding fragment thereof, which (a) specifically binds toxin A of  C. difficile  and which cross competes for binding to toxin A of  C. difficile  with a monoclonal antibody produced by a hybridoma cell line deposited under ATCC Accession No. PTA-9692, PTA-9694, or PTA-9888, and/or which (b) specifically binds to a  C. difficile  toxin A epitope defined by a monoclonal antibody produced by the hybridoma cell line deposited under ATCC Accession No. PTA-9692, PTA-9694, or PTA-9888. 
     
     
         2 . The antibody, or antigen-binding fragment thereof, of  claim 1 , wherein the monoclonal antibody, or antigen-binding fragment thereof, is in a chimeric or humanized form. 
     
     
         3 . An isolated antibody or an antigen-binding fragment thereof, which (a) specifically binds toxin B of  C. difficile  and which cross competes for binding to toxin B of  C. difficile  with a monoclonal antibody produced by the hybridoma cell line deposited under ATCC Accession No. PTA-9693, and/or which (b) specifically binds to a  C. difficile  toxin B epitope defined by a monoclonal antibody produced by the hybridoma cell line deposited under ATCC Accession No. PTA-9693. 
     
     
         4 . The antibody, or antigen-binding fragment thereof, of  claim 3 , wherein the monoclonal antibody, or antigen-binding fragment thereof, is in a chimeric or humanized form. 
     
     
         5 - 12 . (canceled) 
     
     
         13 . An expression vector comprising at least one nucleic acid molecule encoding the antibody or antigen-binding fragment of  claim 1 . 
     
     
         14 - 37 . (canceled) 
     
     
         38 . A composition comprising the antibody or antigen-binding fragment thereof of  claim 1  and a pharmaceutically acceptable carrier, excipient, or diluent. 
     
     
         39 . The composition of  claim 38 , wherein the composition further comprises an additional therapeutic agent. 
     
     
         40 - 63 . (canceled) 
     
     
         64 . A method of treating  C. difficile  infection,  C. difficile -associated disease, or  C. difficile -associated diarrhea (CDAD) in a subject, which comprises administering to the subject the composition of  claim 38  in an amount effective to treat the  C. difficile  infection or  C. difficile -associated disease. 
     
     
         65 - 75 . (canceled) 
     
     
         76 . A method of neutralizing toxins produced by a hypervirulent strain of  C. difficile , which comprises administering to a subject in need thereof an antibody or antigen-binding fragment thereof of  claim 1 , in an amount effective to neutralize the toxins produced by the hypervirluent strain. 
     
     
         77 - 123 . (canceled) 
     
     
         124 . The antibody of  claim 1 , wherein the heavy chain of the antibody is of the IgG class. 
     
     
         125 . The antibody of  claim 124 , wherein the heavy chain of the antibody is of the IgG1 class. 
     
     
         126 . The antibody of  claim 1 , wherein the light chain of the antibody is of the K isotype. 
     
     
         127 - 134 . (canceled) 
     
     
         135 . A method of generating an anti- C difficile  toxin A-neutralizing monoclonal antibody directed against toxin A of  C difficile  or an anti- C difficile  toxin B-neutralizing monoclonal antibody directed against toxin B of  C difficile , comprising:
 (a) immunizing one or more recipient animals with inactive toxoid A at periodic intervals;   (b) boosting the animals with increasing amounts of active toxin A or active toxin at periodic intervals; and   (c) obtaining hybridoma cells from immune cells of the immunized and boosted animals fused with a suitable immortalized cell line, wherein the hybridoma cells produce and secrete anti-toxin A antibodies which neutralize toxin A of  C difficile  or anti-toxin B antibodies which neutralize toxin B of  C difficile.      
     
     
         136 . The method of  claim 135 , further comprising:
 (d) isolating the anti- C difficile  toxin A-neutralizing monoclonal antibodies or the anti- C difficile  toxin B-neutralizing monoclonal antibodies.   
     
     
         137 - 180 . (canceled)