Specificity of protective immunity induced by porin from Salmonella typhimurium

The specificity of protective immunity against Salmonella typhimurium in mice immunized with porins from S. typhimurium, Salmonella enteritidis and Escherichia coli was studied. High levels of protection against S. typhimurium-infection were achieved in mice immunized with porins from S. typhimurium but not from S. enteritidis and E. coli. However, our serological studies demonstrated that porins from S. typhimurium, S. enteritidis and E. coli had antigenic cross-reactivity with each another; in particular, porins immunized with porins from S. typhimurium but not from S. enteritidis or E. coli exhibited the most significant levels of delayed type hypersensitivity reaction, interleukin-2 production and interferon-gamma production when they were elicited with whole cells of S. typhimurium. These observations suggested that the high levels of protection obtained by porin-immunization resulted from the induction of serovar specific cell-mediated immunity.