Hybrid Vibrio vulnificus

Abstract

The recent emergence of the human-pathogenic Vibrio vulnificus in Israel was investigated by using multilocus genotype data and modern molecular evolutionary analysis tools. We show that this pathogen is a hybrid organism that evolved by the hybridization of the genomes from 2 distinct and independent populations. These findings provide clear evidence of how hybridization between 2 existing and nonpathogenic forms has apparently led to the emergence of an epidemic infectious disease caused by this pathogenic variant. This novel observation shows yet another way in which epidemic organisms arise.

Figure 1

Triangle plots of STRUCTURE results. Only 2 populations were identified (A and B). Figure 1A shows the distribution of the biotypes within the 2 populations. B shows the distribution of the strains according to their source (human or environmental). C shows the strains distribution according to their geographic origin. These results were produced by the linkage model of STRUCTURE with K = 3.

Figure 2

Results of a Bayesian cluster analysis by STRUCTURE. Each of the strains included in the analysis is represented by a thin vertical line, partitioned into 2 colored segments that represent the proportion of polymorphic sites inherited from each of the 2 genetic ancestries. For the representation of results, strains were grouped according to biotype. The analysis was carried out by using the linkage model with K = 2.

Figure 3

A neighbor-joining tree of representative isolates from the 2 populations is plotted with the inferred ancestral sources of individual polymorphic sites in each of the 10 genes. The names of the genes and to which chromosome they belong are indicated. These results are based on using the linkage model of STRUCTURE with K = 2.