Interactions between vibrio parahaemolyticus and human and oyster phagocytes

Abstract

Vibrio parahaemolyticus is a Gram-negative halophilic bacterium and is the leading cause of bacterial seafood-borne gastroenteritis worldwide. V parahaemolyticus possesses two type III secretion systems (T3SS); one on each of the two chromosomes. The T3SS-I is present in all strains examined to date, whereas the T3SS-II is found primarily in toxigenic strains associated with human disease. This work examines the interaction of the bacterium in the presence of oyster hemocytes and human neutrophils in an effort to understand how the T3SSs contribute to survival in each respective niche. Various gene expression, protein secretion and phagocytosis assays were carried out with oyster hemocytes, and the overall V parahaemolyticus and neutrophil interaction was studied with bacterial and cellular viability assays. The results suggest that the T3SS-I contributes to an antiphagocytic effect in oyster hemocytes, and may mediate neutrophil cytotoxicity. Further characterization of these interactions is required to determine the mechanism behind these findings.