title: Genetic diversity of Vibrio parahaemolyticus strains isolated from farmed Pacific white shrimp and ambient pond water affected by acute hepatopancreatic necrosis disease outbreak in Thailand.
abstract: Acute hepatopancreatic necrosis disease (AHPND) is an emerging shrimp disease that causes massive die-offs in farmed shrimps. Recent outbreaks of AHPND in Asia have been causing great losses for shrimp culture and have become a serious socioeconomic problem. The causative agent of AHPND is Vibrio parahaemolyticus, which is typically known to cause food-borne gastroenteritis in humans. However, there have been few reports of the epidemiology of V. parahaemolyticus AHPND strains, and the genetic relationship among AHPND strains is unclear. Here, we report the genetic characterization of V. parahaemolyticus strains isolated from AHPND outbreaks in Thailand. We found eight isolates from AHPND-suspected shrimps and pond water that were positive for AHPND markers AP1 and AP2. PCR analysis confirmed that none of these eight AP-positive AHPND strains possesses the genes for the conventional virulence factors affecting to humans, such as thermostable direct hemolysin (TDH), TDH-related hemolysin (TRH) and type III secretion system 2. Phylogenetic analysis by multilocus sequence typing showed that the AHPND strains are genetically diverse, suggesting that AHPND strains were not derived from a single genetic lineage. Our study represents the first report of molecular epidemiology of AHPND-causing V. parahaemolyticus strains using multilocus sequence typing, and provides an insight into their evolutionary mechanisms.
authors.affiliation: Department of Microbiology, Faculty of Public Health, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Kaknokrat
authors.initials: K
authors.lastname: Chonsin
authors.affiliation: Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Shigeaki
authors.initials: S
authors.lastname: Matsuda
authors.affiliation: Department of Microbiology, Faculty of Public Health, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Chonchanok
authors.initials: C
authors.lastname: Theethakaew
authors.affiliation: Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Kodama
authors.affiliation: Department of Microbiology, Faculty of Public Health, Mahidol University, Bangkok 10400, Thailand.
authors.forename: Jiraphan
authors.initials: J
authors.lastname: Junjhon
authors.affiliation: Division of Bioresources, Hokkaido University Research Center for Zoonosis Control, Sapporo 001-0020, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Department of Microbiology, Faculty of Public Health, Mahidol University, Bangkok 10400, Thailand Center of Ecohealth Education and Research, Faculty of Public Health, Thammasat University, Rangsit Center, Pathum Thani 12121, Thailand.
authors.forename: Orasa
authors.initials: O
authors.lastname: Suthienkul
authors.affiliation: Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan iida@biken.osaka-u.ac.jp.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Iida
mesh_terms: D000208:Acute Disease / Q000453:epidemiology; D000818:Animals; D017756:Aquaculture; D004196:Disease Outbreaks; D005506:Food Contamination / Q000032:analysis; D005618:Fresh Water / Q000382:microbiology*; D014644:Genetic Variation; D006801:Humans; D008969:Molecular Sequence Data; D033561:Penaeidae / Q000254:growth & development / Q000382:microbiology*; D010802:Phylogeny; D017747:Seafood / Q000382:microbiology*; D013785:Thailand / Q000453:epidemiology; D014735:Vibrio Infections / Q000453:epidemiology / Q000382:microbiology*; D014736:Vibrio parahaemolyticus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*
keywords: Vibrio parahaemolyticus; acute hepatopancreatic necrosis disease; multilocus sequence typing