Antigens and immunoassays for diagnosing Chagas' disease

Abstract

Transfusion of contaminated blood has become the major route of transmission for Chagas' disease. Current screening tests are insensitive and yield conflicting results, while confirmatory assays do not exist. The present invention relates to antigens and their use for serological diagnosis of Chagas' disease. More specifically, the present invention concerns assays which are able to reliably and accurately detect the presence of antibodies to various specific antigens of Trypanosoma cruzi in a highly sensitive and specific manner.

1 . A composition comprising at least 6 recombinant and/or synthetic peptides which bind to  Trypanosoma cruzi -specific antibodies and do not bind to Leishmania-specific antibodies.  
     
     
         2 . A composition according to  claim 1 , wherein said peptides are derived from the  T. cruzi  antigens chosen from the group consisting of SAPA, CRA, FRA, TcD, Tc24, Ag39 and MAP proteins.  
     
     
         3 . A composition according to  claim 2 , wherein said peptides have amino acid sequences given by SEQ ID No 1 to 7 or any variant thereof.  
     
     
         4 . A method for detecting the presence of  T. cruzi  antibody in a biological sample, comprising: 
 contacting said biological sample with the peptides of the composition according to any of  claims 1  to  3 , and    detecting in a biological sample the presence of antibodies that bind to the peptides of the composition according to any of  claims 1  to  3 .    
     
     
         5 . A method according to  claim 4  wherein the step of detecting comprises: 
 removing unbound sample,  
 adding a detection reagent, and  
 determining the level of reacting antibodies relative to a predetermined cutoff value.  
 
     
     
         6 . A method according to any of  claims 4  to  5  wherein said peptides of the composition according to any of  claims 1  to  3  are bound to a solid support.  
     
     
         7 . A method according to  claim 6  wherein said solid support comprises nylon, nitrocellulose, latex, dextran, gold and/or a plastic material.  
     
     
         8 . A method according to any of  claims 6  to  7  wherein said peptides of the composition according to any of  claims 1  to  3  are bound to a solid support in a line-wise fashion.  
     
     
         9 . A diagnostic kit for detecting  T. cruzi  infection in a biological sample, comprising a composition according to any of  claims 1  to  3 .  
     
     
         10 . A diagnostic kit according to  claim 9  wherein said kit further comprises a detection reagent.