Molecular-genetic peculiarities of classical biotype Vibrio cholerae, the etiological agent of the last outbreak Asiatic cholera in Russia.

Molecular-genetic properties of classical biotype Vibrio cholerae strains that caused the Asiatic cholera outbreak in 1942 in Russia have been investigated for the first time. Being characterized by high-level production of cholera toxin and toxin-coregulated adhesion pili both of which are the major virulence factors, all the strains studied, in contrast to the typical cholera pathogens, were autographic requiring purine and/or amino acids added to the minimal medium for their growth. Moreover, these strains containing the structural gene hapA, as shown by the polymerase chain reaction, produced no soluble hemagglutinin/protease, which enables the vibrios to get disseminated in the environment. The peculiarities of the natural V. cholerae strains elucidated in the work are likely to be responsible for the unusual infectious and epidemic processes observed during that cholera outbreak.