Research Institute for Plague Control, Rostov-on-Don, Russia
Aim. Complex assessment of virulence of cholera vibrios carrying the truncated CTX element (pre-CTXφ prophage). Materials and methods. Twenty-two strains of Vibrio cholerae O1 and non-O1/non-O139 were studied by PCR and laboratory models. Results. Genomes of all strains, besides pre-CTXφ genes, contained genes hapA (hemagglutinin/proteases), cef (CHO cell elongating factor), rtxA (high-molecular cytotoxin), and rtxC (its activator). Nucleotide sequences of rtxA and vgrG genes from ACD domains, genes VPI and VPI-2 from islands of pathogenicity, mshA (mannose-sensitive pili) gene were presented in different combinations. None strains contained shiga-like toxin (slt1) as well as thermostable direct (tdh) and thermostable direct-related (trh) hemolysin genes of V.parahaemoliticus. On the model of infant rabbits almost all strains caused a significant enteropathogenic effect sometimes resembling cholera effect and in a number of cases dissemination of bacteria into various organs and tissues took place. Cultural supernatants of the majority of strains stipulated cell rounding in CHO cultures (one of them caused cell destruction) and disconnection of cells in McCoy and L-929 dense monolayers as well as increase of skin permeability in Craig"s test. Conclusion. Apparently, diarrhea of different severity observed in patients from whom these strains were isolated as well as signs of virulence revealed in the laboratory models were determined by the expression of genes of accessory pathogenicity factors including those detected in the present study.
Zh. Mikrobiol. (Moscow), 2008, No. 4, P. 27—32