[Standardization and evaluation of the modified vibriocidal assay]. / Estandarización y evaluación del ensayo vibriocida modificado.

The vibriocidal antibody test is a reliable and well-documented method to determine bacterial antibodies to Vibrio cholerae 01 antigens. It consists of mixing serum dilutions and a steady quantity of bacteria and supplement to cause cell lysis. Titer is determined by visual observation. In this paper, we implemented a change in the presented method where a pH and glucose indicator was added to the culture medium used to stop the reaction, which allowed a quicker reading by any person who are not very familiar with the carrying out of this test since the colour change in the plaque is quite evident.

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.

[The excretion pattern and protective capacity in rabbits orally immunized with attenuated strains of Vibrio cholerae O1 biotype El Tor]. / Estudio del patrón de excreción y la capacidad protectora en conejos inmunizados de forma oral con cepas atenuadas de Vibrio cholerae O1 biotipo El Tor.

In order to study the excretion patterns, colonization and protective capacity of live attenuated strains of Vibrio cholerae O1. El Tor, rabbits were immunized in New Zealand with these strains and their corresponding parental strains. 2 doses were administered by the model of oral inoculation in adult rabbits. Rabbits were rotated 2 weeks after the second dose by the model of ligated intestine with highly virulent strains of V. cholerae O1 Ogawa and Inaba serotypes and O139 serogroup. It was proved that the genetically manipulated strains do not effect the excretion patterns when they are compared with their parental strains. It was observed in the challenge a decrease in the levels of colonization of virulent strains of both serotypes, not only among the rabbits immunized with the attenuated strains, but also among those immunized with the parental strains in comparison with control animals immunized with the strain of Escherichia coli K-12, which means that there was certain degree of protection. In the case of the animals challenged with the O139 strain it was demonstrated that the protection is specific for each serogroup, since in this case there was no reduction of the colonization.

[Characterization of monoclonal antibodies that recognize the thermolabile toxin of Vibrio cholerae]. / Caracterización de anticuerpos monoclonales que reconocen la toxina termolábil de Vibrio cholerae.

The obtention of two monoclonal antibodies which recognize a single epitope present in the subunit B of the thermolabile toxin of Vibrio cholerae and another which shows a cross-reaction with those produced by certain enteropathogenic toxins, is reported. The standardization of a solid phase indirect immunoenzymatic assay (ELISA) for the primary screening and selection of hybrids was performed; in addition, the isotype was determined.