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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #349104

Research Project: Ecology and Detection of Human Pathogens in the Produce Production Continuum

Location: Produce Safety and Microbiology Research

Title: Prevalence and molecular typing of Vibrio parahaemolyticus isolated from seafood in Shanghai using multilocus sequence typing (MLST)

Author
item Zhang, Yujie - Shanghai Ocean University
item Sun, Xiaohong - Shanghai Ocean University
item Pan, Yingjie - Shanghai Ocean University
item Wu, Vivian

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/9/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Vibrio parahaemolyticus is a gram-negative bacterium that inhabits coastal and marine environments. Thermostable direct hemolysin (tdh), tdh-related hemolysin (trh) and the type III secretion system are considered the potential virulent factors of pathogenic V. parahaemolyticus. The frequency of strains carrying virulent genes may depend on the location and source of the sample. The objective of this study was to use the multilocus sequence typing (MLST) which is based on sequence analysis of 7 chosen housekeeping (HK) genes for analyzing the genetic variability of 107 V. parahaemolyticus strains (5 tdh+ strains,1 trh+ strain and 101 non-pathogenic strains) in seafood obtained from the market in Shanghai. All strains were isolated from seafood in Shanghai and analyzed for the presence of tdh and trh genes by PCR. Genomic DNA was extracted from 107 V. parahaemolyticus isolates. Molecule typing was performed using the multilocus sequence typing (MLST). The alignments and sequence type (STs) according to the database created for V. parahaemolyticus were assigned. PHYLOViZ software was used to identify the clonal complexes (CC), single-locus variant (SLV) and Double-locus variants (DLV). Then the ME tree was structured by Mega-5 software according to each locus and the concatenated sequences of each ST (3,682 bp) was obtained using the the Kimura two-parameter model to estimate the genetic distances. The results indicated that 92 of the 107 strains generated 46 STs. There were one CC410 (contains ST355, ST399 and ST41), two doubles and 39 singletons. These results demonstrated that MLST has high discernibility in molecular typing. Thus, the ME tree results showed that the clonal complex and the two doubles were clustered together, illuminating the variability particularly. Additionally, four tdh+ strains were found in same cluster which implied that these pathogenic strains may originate from one ancestor. The finding of this study indicated that there was relatively small foodborne risk associated with the sampled seafood in Shanghai. The genetic variability and distribution of V. parahaemolytius isolated from seafood in this study could be useful for further epidemiological studies.