Genetic relationship of pathogenic Vibrio cholerae clones by sequence analysis of two housekeeping genes

ABSTRACT

Background: Evaluation of genetic relationship of pathogenic Vibrio cholerae clones isolated from specimens and different areas throughout analysis of various genes\u2019 sequence, in particularly, housekeeping genes provides the most accurate molecular database to molecular epidemiological surveillance. Objective: To evaluate the genetic relationship of pathogenic Vibrio cholerae clones in Vietnam to some other pathogenic clones throughout analysis of 2 housekeeping genes\u2019 sequence mdh and hlyA. Subject and methods: 2 housekeeping genes, mdh (malate dehydrogenase) and hlyA (hemolysin) were sequenced and submitted to the GeneBank with accession numbers AJ575356 and AJ576090. These sequences were compared with mdh and hlyA sequences from pathogenic strains of sixth and seventh cholera pandemics and from environmental strains. Results and Conclusion: The analysis results by MEGA3.0 software showed that the mdh and hlyA sequences from the pathogenic clones of Vietnam, sixth pandemic and seventh pandemic were rather similar, although having 11-bp deletion in hlyA gene of sixth pandemic clone. The 11-pb deletion in hlyA of the sixth pandemic clone was a characterization that distinguished the classical and El Tor types. Phylogenetic tree were constructed by the neighbor-joining method based on the mdh and hlyA sequences indicated that the Vietnam strain was very closely related to strains of sixth and seventh pandemics (the genetic distance 0.2%). This evidenct suggested that the pathogenic clone in Vietnam diverged from a common ancestor with the sixth and seventh pandemic clones which had the intact properties of the pathogenic agent. \r\n', u'\r\n', u'