A Three-Loci Variable Number of Tandem Repeats Analysis for Molecular Subtyping of Vibrio cholerae O1 and O139

Rapid and easy-to-use molecular subtyping methods are being explored and used for the surveillance of bacterial diseases, including multiple-loci variable number of tandem repeats (VNTR) analysis (MLVA). In this study, we assessed different VNTR combinations for the subtyping of Vibrio cholerae serogroups O1 and O139 with strain panels selected from a long-term nationwide cholera survey. By only using three highly variable loci (VC0147, VCA0171, and VCA0283), we acquired a high discriminatory power, which equals that found after using a combination of all nine loci and that of a pulsed-field gel electrophoresis analysis. Evaluation using the outbreak strains showed a good clustering of the three-loci MLVA (VC0147, VCA0171, and VCA0283). In addition, a six-loci MLVA (VC0147, VC0437, VC1457, VC1650, VCA0171, and VCA0283) protocol allowed for the clustering of O1/O139 V. cholerae strains, which have different serogroups/biotypes and toxigenic/nontoxigenic characteristics. Here, we propose that the three-loci MLVA can be utilized as a molecular subtyping protocol in cholera epidemiological investigations, and the six-loci MLVA can be used in phylogenetic and population structure analyses of V. cholerae O1/O139.