GENES WITHIN THE MAJOR HISTOCOMPATIBILITY COMPLEX INFLUENCE THE RESPONSE TO AMPICILLIN THERAPY AND SEVERITY OF RELAPSE IN H‐2 CONGENIC, SUSCEPTIBLE Itys MICE INFECTED WITH VIRULENT SALMONELLA TYPHIMURIUM

Abstract

Control by genes within H-2 of natural resistance to fully virulent salmonellae in susceptible mice was studied by the typhoid relapse model. Susceptiblel (Itys), H-2 congenic C57BL/10 (B10) lines were infected with a lethal dose of the virulent S. typhimurium C5 and rescued from death by ampicillin therapy, inducing a chronic infection. The response to therapy and its cessation, both early and late in the infection, varied in different strains. B10 (H-2b) and B10.D2 (H-2d) responded less well to therapy, and were more prone to relapse on its removal, than B10.A (H-2a) or B10.M (H-2f) mice. This haplotype distribition is the same as that previously reported for H-2 linked resistance and susceptibility of similar mice to salmonellae of low virulence. The results indicate that resistance to a virulent salmonella capable of causing natural infection is influenced by genes within the MHC.