Virulence factors involved in the intraperitoneal infection of adult mice with Vibrio cholerae.

Nonmotile mutants of Vibrio cholerae isolated from Ogawa, Inaba, and El Tor strains were less virulent than parent wild types when administered to adult mice intraperitoneally. The cells were suspended in 5% hog gastric mucin. Antitoxic immunity did not protect mice against this type of challenge, but a ribosomally derived vaccine did. Intraperitoneal injection of 10 50% lethal doses of enterotoxin (based on intravenous doses) was without toxic manifestations as were 10(10) heat-killed vibrios similarly administered, regardless of strain. Virulent organisms killed with formalin or ultraviolet irradiation were significantly lethal at a dose of 10(10) cells. Mice made tolerant to endotoxin were protected from death caused by an injection of 3 X 10(10) boiled cells, but they did not survive an injection of formalin-killed cells. It is believed that the cause of death in this animal model of cholera is dependent, at least in part, on a toxic heat-labile moiety closely associated with the vibrios.