Influence of oyster genetic background on levels of human-pathogenic Vibrio spp.

Human-pathogenic Vibrio bacteria are common inhabitants of oyster tissues, but our understanding of factors driving the wide range of concentrations found in individual oysters is extremely limited. We examined the influence of oyster sex and parasitism in light of their profound effects on oyster tissues against a backdrop of eastern oysters, Crassostrea virginica, from two diploid and two triploid aquacultured lines. This allowed us to examine not only the effect of oyster ploidy but also of oyster genetics, a factor never investigated with regard to human-pathogenic Vibrio species. We measured levels of total Vibrio vulnificus (vvhA), and of total (tlh) and pathogenic (tdh+, trh+) V. parahaemolyticus, in each oyster, and analyzed the data through generalized linear mixed-effects models. A key outcome of these analyses was the consistent inclusion of oyster line as a predictor variable across Vibrio targets. A potential effect of Perkinsus marinus infections and/or oyster sex was also sug-gested, although the combination of variables varied with Vibrio target. This study suggests that the influence of oyster genetic background should be further investigated, and that the dynamics of human-pathogenic Vibrio spp. in oysters is likely driven by multiple, interacting factors, some of which may be under oyster host genetic control.