PASSIVE-IMMUNITY TO INFECTION WITH YERSINIA SPP MEDIATED BY ANTI-RECOMBINANT V-ANTIGEN IS DEPENDENT ON POLYMORPHISM OF V-ANTIGEN

The V antigen is a 37-kDa secreted polypeptide encoded on the 70-kb vi rulence plasmid of pathogenic Yersinia spp, Besides having regulatory functions, it is known to be a virulence factor and a protective antig en, DNA sequencing of the most common serotypes of human pathogenic Ye rsinia enterocolitica and Y. pseudotuberculosis revealed that two evol utionary distinct types of V antigen exist in Yersinia spp, One type i s represented by Y. enterocolitica serotype O8 strains WA, WA-314, and NCTC 10938 (designated LcrV-YenO8); the other type comprises Y. pesti s, Y. pseudotuberculosis, and Y. enterocolitica serotypes O3, O9, and O5,27 (LcrV-Yps), A hypervariable region between amino acids 225 and 2 32 represents the main difference between the two types, By raising mo nospecific antisera against both types of V antigen (anti-rVO8 and ant i-rVO3), we were able to demonstrate that, in general, passive immuniz ation of mice against a challenge with yersiniae was possible with bot h anti-Y. enterocolitica V antigen sera, However, anti-V antigen serum was protective only if the immunizing V antigen was the same type as the V antigen produced by the infective strain, The failure of the Ame rican V antigen type represented by Y. enterocolitica serotype O8 to p rotect against Yersinia spp, carrying the other V antigen type (LcrV-Y ps) could be an explanation for the presence of plague foci in America n countries.