Immunity toVibrio choleraeInfection

Abstract

This chapter outlines present knowledge on the immune mechanisms operating against cholera based on studies of experimental animals infected with Vibrio cholerae as well as of humans living in areas where cholera is endemic or convalescing from cholera disease. Owing to the critical role of cholera toxin (CT) in the pathogenesis of V. cholerae O1, much interest has been focused on the importance of antitoxic immunity for protection against cholera. Although lipopolysaccharide (LPS) apparently is responsible for much of the antibacterial cholera immunity induced, both by cholera vaccines and by V. cholerae infection, additional antigens, some of which may be expressed only during certain culture conditions or during growth in the intestine, may contribute to antibacterial protective immunity. The immune responses induced by clinical cholera in humans appear to be very efficient in providing prolonged protective immunity against subsequent infection with V. cholera O1 bacteria. Symptomatic or asymptomatic infections with V. cholerae in early childhood may result in partial or complete immunity to cholera disease or even infection. Studies of the incidence of diarrhea in breast-fed children also suggest a protective effect of antitoxic as well as antibacterial antibodies in milk against cholera. The protective role of these antibodies has been difficult to assess, e.g., by comparing diarrhea morbidity in breast-fed and bottle-fed children, owing to several confounding factors.