[Prophage CTXphi genome variability and its role in alteration of Vibrio cholerae El Tor virulence characteristics].

Comparative analysis of CTXphi prophage genome of 366 V. cholerae El Tor strains isolated from infected people and water was carried out using the polymerase chain reaction. Four groups of vibrios, which carry different combinations of ctxA, zot, and ace genes from core region of CTXphi prophage coding key (cholera enterotoxin) and accessory (Zot and Ace toxins) pathogenicity factors, were determined: ctxA(+) zot(-) ace(+), ctxA(-) zot(+) ace(+), ctxA(-) zot(+) ace(-), ctxA(-) zot(-) ace(+).

[A study of the prevalence of regulatory genes controlling virulence gene expression among Vibrio choleraeeltor biovariant strains varying in their pandemic potential].

The evolution of the genome of the pathogenic agent of the seventh cholera pandemia Vibrio cholerae eltor biovariant was thought to occur by acquiring not only structural genes of virulence but also regulatory systems as a result of horizontal transfer events. The polymerase chain reaction revealed the presence of the following regulatory genes that control the virulence gene expression in the chromosome of pre-pandemic and pandemic strains of cholera vibrios eltor: toxR, toxT, tcpP, tcpH, luxS, luxO, crp, vicH, pepA. The avirulent V.

[Comparative genomic analysis of vibrio cholerae El Tor preseventh and seventh pandemic strains isolated in various periods].

Genetic organization of 52 Vibrio cholerae El Tor biotype preseventh and seventh pandemic strains isolated in various periods was studied by PCR assay and DNA-DNA hybridization. It was established that the genome of most ancient of analyzed strains isolated from a diarrhea patient in 1910 was devoid of CTX and RS1 prophages, vibrio pathogenicity islands (VPI and VPI-2), and pandemic islands (VSP-1 and VSP-2) that contain key virulence genes. The appearance of pathogenic properties in cholera vibrios for the first time causing a local outbreak of cholera in 1937 is connected with the acquisition of VPI and CTX that carried genes tcpA and ctx-AB, respectively, which are responsible for the colonization of small intestine and encode the production of cholera toxin.