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Smirnova N.I.,Russian Scientific Research Anti Plague Institute Mikrob | Zadnova S.P.,Russian Scientific Research Anti Plague Institute Mikrob | Shashkova A.V.,Russian Scientific Research Anti Plague Institute Mikrob | Kutyrev V.V.,Russian Scientific Research Anti Plague Institute Mikrob
Molecular Genetics, Microbiology and Virology | Year: 2011

Molecular-genetic analysis of 56 clinical strains of the Vibrio cholerae biovar El Tor isolated during the period 1965-2010 in Russia and neighboring countries was carried out. Thirty-one isolates (55.3%) bear- ing the gene ctxB in the genome of the prophage CTXφ in cholera vibrios of the classical biovar were found. These strains are altered variants of the cholera El Tor pathogen. The nucleotide sequence of their genes ctxB and rstR included in the prophage CTXφ, which are related with the production of the cholera toxin, was determined. It was found that altered variants bear different alleles of these genes (ctxB1 or ctxB7; rstREl and/or rstRClass) and belong to four gene types: ctxB1, rstRClass; ctxB1, rstR El; ctxB1, rstRClass/rstREl; and ctxB7, rstRClass/rstREl. It was shown that these gene variants produce 42 to 48 times more cholera toxin than typical strains. Isolates in which the pathogenicity island VSP-2 contains a long deletion were found among altered variants. The study data are evidence of the genomic variability of altered pathogen variants of the sev- enth cholera pandemic and require the development of new gene-diagnostic testing systems to improve the efficiency of epidemiological control of cholera distribution. © Allerton Press, Inc., 2011.

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