[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.

Synthesis of terminal disaccharide elements corresponding to the Ogawa and Inaba antigenic determinant from Vibrio cholerae O1.

Vibrio cholerae O1 LPS terminal mono- and disaccharide elements were synthesized by reduction of the azido group in several 4-amino-4,6-dideoxy-D-mannose mono- and disaccharide derivatives, followed by coupling with 2, 4-di-O-acetyl-3-deoxy-L-glycero-tetronic acid in the presence of 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline. This compound represents a useful model in order to elucidate the size of the epitopes which define Ogawa and Inaba serotypes from Vibrio cholerae O1.

[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.

[Immunity against Neisseria meningitidis in different population groups]. / Inmunidad contra la Neisseria meningitidis en diferentes grupos de la población.

The determination of titers of antibodies to A and C meningococcal capsular polysaccharides by means of passive hemagglutination, proved useful in the evaluation of the effects of vaccination in a group of adults. The determination of titers of antibodies to serogroup B polysaccharide showed differences among the groups of individuals subjected to different degrees of exposure to Neisseria meningitidis. A positive correlation was found between the titer of passive hemagglutination and the number of units of IgG antibodies to polysaccharide C, determined by immunoenzymatic analysis in a group of 10 people administered an experimental vaccine.