Intestinal colonization of the infant mouse model by attenuated and virulent Vibrio cholerae strains.

BACKGROUND: Intestinal colonization of humans with virulent Vibrio cholerae stimulates substantial, lasting immunity against reinfection. The purpose of this study was to evaluate the colonizing capability of various Vibrio cholerae strains which are promising candidates to oral vaccine. METHODS: Infant mouse model modification was used. In order to standardize the method, several parameters were tested, such as culture medium and optimal time of incubation and appropriate number of cells to be inoculated. The following were tested: Vibrio cholerae strain 81, 413, and 251A, which were obtained at the Molecular Biology Department of the National Center for Scientific Research, Havana, Cuba. Their virulence cassettes which code for the main virulence factors were deleted. RESULTS: Good variance coefficient (VC) was obtained in repeated experiments. The colonizing properties of attenuated Vibrio cholerae strains evaluated by this method correlated well with those observed for parental strains. CONCLUSIONS: Genetically attenuated Vibrio cholera strains have the same intestinal colonization level as their parental strains in the infant mouse model; thus, genetic manipulation does not affect genes that encode for the synthesis of colonization factors.