Developing a novel molecular serotyping system based on capsular polysaccharide synthesis gene clusters of Vibrio parahaemolyticus

Abstract

Vibrio parahaemolyticus is a major food-borne pathogen. V. parahaemolyticus infections are associated with various serotypes; to date, 71 K-serogroups of V. parahaemolyticus have been determined based on capsular polysaccharide (CPS) diversity. In this study, the capsular polysaccharide gene clusters (CPSgcs) of 55 K-serogroups were identified by whole-genome sequencing and analysis. These CPSgcs exhibit a high level of genetic diversity. A microsphere-based suspension array (MSA) was established for the detection and identification of 55 V. parahaemolyticus K-serogroups based on CPSgc-specific genes. To evaluate our array, a double-blind test with 120 clinical isolates was carried out. In addition, an in silico K-serotyping system was established based on V. parahaemolyticus CPSgc-specific genes. This system was then used to examine 845 publicly available V. parahaemolyticus genomes; the results demonstrated that 813 isolates belong to one of 43 K-serogroups. Taken together, these results demonstrate that the molecular system developed in this study is suitable for rapid serotyping of V. parahaemolyticus isolates from environmental and clinical samples. In addition, the system could be applied to epidemiological investigations of this important food-borne pathogen.