title: Allelic diversity and population structure in Vibrio cholerae O139 Bengal based on nucleotide sequence analysis.
abstract: Comparative analysis of gene fragments of six housekeeping loci, distributed around the two chromosomes of Vibrio cholerae, has been carried out for a collection of 29 V. cholerae O139 Bengal strains isolated from India during the first epidemic period (1992 to 1993). A toxigenic O1 ElTor strain from the seventh pandemic and an environmental non-O1/non-O139 strain were also included in this study. All loci studied were polymorphic, with a small number of polymorphic sites in the sequenced fragments. The genetic diversity determined for our O139 population is concordant with a previous multilocus enzyme electrophoresis study in which we analyzed the same V. cholerae O139 strains. In both studies we have found a higher genetic diversity than reported previously in other molecular studies. The results of the present work showed that O139 strains clustered in several lineages of the dendrogram generated from the matrix of allelic mismatches between the different genotypes, a finding which does not support the hypothesis previously reported that the O139 serogroup is a unique clone. The statistical analysis performed in the V. cholerae O139 isolates suggested a clonal population structure. Moreover, the application of the Sawyer's test and split decomposition to detect intragenic recombination in the sequenced gene fragments did not indicate the existence of recombination in our O139 population.
authors.affiliation: Departament de Microbiologia i Parasitologia Sanitàries, Divisió de Ciències de la Salut, Universitat de Barcelona, Avda. Joan XXIII s/n, E-08028 Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Farfán
authors.forename: D
authors.initials: D
authors.lastname: Miñana-Galbis
authors.forename: M C
authors.initials: MC
authors.lastname: Fusté
authors.forename: J G
authors.initials: JG
authors.lastname: Lorén
mesh_terms: D000483:Alleles; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002771:Cholera / Q000453:epidemiology* / Q000382:microbiology; D004196:Disease Outbreaks; D014644:Genetic Variation; D006801:Humans; D015810:Linkage Disequilibrium; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D014734:Vibrio cholerae / Q000145:classification / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins