In Rostov region of Russian Federation during more than 50 years a rather heterogeneous population of Vibrio cholerae non-O1/non-O139 (NAGs) does exist, whose representatives periodically cause acute intestinal infections in humans; the last single case was registered in 2018. In 2022 in Rostov, a sick child was again revealed, from which 2 subcultures of NAGs were isolated with a 3-day interval. Aim of the study: bioinformatics analysis of whole genome sequences of the clinical V. cholerae nonO1/nonO139 strain isolated in 2022, genetic determinants of pathogenicity factors and their deduced products. Materials and methods. Isolation and identification of cultures by phenotype and in PCR, determination of their antibiotic sensitivity was carried out according to MUK 4.2.3745-22. Whole genome sequencing was performed on the MiSeq Illumina platform, SNP analysis of the resulting sequences (WGSs) was accomplished using authors software. BioEdit 7.2.5 software was used to identify determinants of pathogenicity factors in genomes, drug resistance genes were identified using the CARD database, bioinformatics analysis of genes and their deduced products were conducted using the Vector NTI Advance 11 package (Invitrogen). Results. The isolated cultures were identical in terms of morphological and biochemical features characteristic for the V.cholerae species; they were not agglutinated by O1, Ogawa, Inaba, O139, RO sera. According to PCR results, they had the genotype ctxA-, tcpА-, hly+, wbeО1-, wbf О139-, i.e. were non-toxigenic NAGs. Both showed sensitivity to levomycetin, ceftriaxone, streptomycin, gentamicin, nalidixic acid, cifprofloxacin, ampicillin, amikacin and intermediate resistance to tetracycline, doxycycline, furazalidon and co-trimoxazole. SNP analysis also showed their identity. WGSs lacked CTX and preCTX prophages, pathogenicity island VPI, thermostable and cholix toxin genes, pandemic islands VSP-I and VSP-II. An intact type 3 secretion system (T3SS) cluster was identified, which was adjacent to the nan-nag region of the VPI-2 pathogenicity island in the absence of the proximal and distal parts of this island. The determinants of another contact-dependent secretion system, T6SS, were not presented completely, which evidenced in favor of the loss of its functionality. Other determinants of pathogenicity factors were present: RTX cluster responsible for synthesis of MARTX cytotoxin, genes for hemolysin/cytolysin HlyA, cytotonic toxin Cef, and several serine and metalloproteases, which in a varying degree might be involved in pathogenesis. The nucleotide compositions of most listed determinants differed significantly from the prototypes, but were intact, and their deduced products preserved their characteristic active domains. The adhesive activity in the absence of TCP could be provided by mannose-insensitive MSHA-like pili, since the msh-cluster included all the genes necessary for their production, as well as flagella, as both clusters responsible for their assembling were 99% identical to the prototype. Virtually no antibiotic resistance genes have been found, excluding -lactamase VarG gene responsible for resistance to penicillins. Conclusion. Thus, the NAG strain under study contains a sufficient amount of intact virulence-associated genetic determinants, the expression of which could contribute to the development of the disease. The permanent presence of NAGs with diverse sets of pathogenicity factor genes in water bodies and their possible persistence in the organism of asymptomatic carriers provides conditions for the processes of genetic exchange and formation of new, probably more virulent clones, therefore this group of microorganisms demands attention when monitoring cholera vibrios in the Russian Federation.
