Variability of cef Genes in Toxigenic and Non-Toxigenic Vibrio cholerae O1 Strains

Abstract

Objective of the investigation was a comparative bioinformatics analysis of Vibrio cholerae О1 Cef (CHO cell elongating factor) genes and proteins. Materials and methods. 36 Vibrio cholerae О1 strains from the Rostov-on-Don Research Anti-Plague Institute collection have been utilized. DNA sequencing was conducted on the MiSeq platform (Illumina); gene identification and analysis was carried out by means of BioEdit 7.2.5, BLASTN 2.2.29, BLASTP, MEGA 7, Vector NTI Advance 11 software programs. Results and conclusions. The data obtained confirmed Cef to be rather conserved in choleragenic strains (carrying cholera toxin genes ctxAB as a part of genome-integrated CTX prophage): all of them shared closely related prototype alleles cefС or cefЕ1. The Е1 allele was also revealed in ctxAB– strains carrying the pre-CTX prophage and in a single strain lacking both prophages. In the rest of CTX–/pre-CTX– V. cholerae four novel cef variants, that were not previously described, have been identified, two of which (E2 and E3), belonging to the Russian isolates, appeared to be unique, while for the two others absolute homologues were found in NCBI. In this connection several strains which caused severe cholera-like diseases in humans were placed in the group of cefЕ4 host strains. Since Cef is one of pathogenicity/persistence factors of cholera vibrios, we presume that conservation of its altered variants in the course of natural selection embodies a certain biological sense in respect of possible acquisition of qualities, significant for realization of both pathogenic and persistence potential.