Method of isolating a peptide which immunologically mimics microbial carbohydrates including group B streptococcal carbohydrates and the use thereof in a vaccine

Abstract

This invention relates to new vaccines against microorganisms based on antigenically mimetic peptides. The invention also relates to methods of discovering such mimetic peptides by first screening peptide-display phage libraries with antibodies against the microbial carbohydrates(s) of interest to locate antigenically mimetic peptides. Vaccines against Group B Streptococcus, or Streptococcus Agalactiae , are preferably produced using this method.

I claim:  
     
         1 . A method of isolating a peptide which immunologically mimics a portion of a Group B streptococci, comprising the steps of: 
 (1) identifying protective antibodies reactive with said Group B streptococci;    (2) contacting a phage-display library, having phage, with one or more of said protective antibodies identified in step 1;    (3) isolating one or more phage, having a displayed peptide, which binds one or more of the protective antibodies; and    (4) selecting, for all said phage isolated in step 3, the peptides or peptide fragments to which the antibodies have bound.    
     
     
         2 . The method of  claim 1  wherein the portion of the Group B Streptococci is a carbohydrate.  
     
     
         3 . The method of  claim 2 , wherein the carbohydrate is a Type III capsular polysaccharide.  
     
     
         4 . A mimetic peptide that induces antibodies against a portion of a Group B streptococci.  
     
     
         5 . The peptide of  claim 4  wherein the portion of the Group B Streptococci is a carbohydrate.  
     
     
         6 . The peptide of  claim 5  wherein the carbohydrate is a Type III capsular polysaccharide.  
     
     
         7 . The peptide of  claim 4  having a sequence selected from the group consisting of FDTGAFDPDWPA (SEQ ID NO: 1), FDTGAFDPDWPAC (SEQ ID NO:2), WENWMMGNA (SEQ ID NO:3), and WENWMMGNAC (SEQ ID NO:4).  
     
     
         8 . A vaccine, comprising: 
 a mimetic peptide that induces antibodies against a portion of a Group B streptococci and    a pharmaceutically acceptable carrier.    
     
     
         9 . The vaccine of  claim 8  wherein the portion of the Group B Streptococci is a carbohydrate.  
     
     
         10 . The vaccine of  claim 9  wherein the carbohydrate is a Type III capsular polysaccharide.  
     
     
         11 . The vaccine of  claim 8  wherein the mimetic peptide has a sequence selected from the group consisting of FDTGAFDPDWPA (SEQ ID NO:1), FDTGAFDPDWPAC (SEQ ID NO:2), WENWMMGNA (SEQ ID NO:3), and WENWMMGNAC (SEQ ID NO:4),  
     
     
         12 . A method of treating a patient, comprising administering to the patient an immunostimulatory amount of a vaccine, comprising: 
 a mimetic peptide that induces antibodies against a portion of a Group B streptococci and    a pharmaceutically acceptable carrier.    
     
     
         13 . The method of  claim 12  wherein the portion of the Group B Streptococci is a carbohydrate.  
     
     
         14 . The method of  claim 13  wherein the carbohydrate is a Type III capsular polysaccharide.  
     
     
         15 . The method of  claim 12  wherein the mimetic peptide has a sequence selected from the group consisting of FDTGAFDPDWPA (SEQ ID NO:1), FDTGAFDPDWPAC (SEQ ID NO:2), WENWMMGNA (SEQ ID NO:3), and WENWMMGNAC (SEQ ID NO:4)