Genetic diversity ofVibrio parahaemolyticusstrains 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.

The B Subunit of PirABvp Toxin Secreted from Vibrio parahaemolyticus Causing AHPND Is an Amino Sugar Specific Lectin

“…The presence of genes encoding PirA and PirB was reported in the Gram-positive bacterial species Micrococcus luteus [12]. This bacterium was isolated in 2006 from the Hp of farmed P. vannamei shrimp collected in Nayarit, Mexico; it is possible that the toxin was acquired by horizontal gene transfer from AHPND isolates [13,14]. The genome of Vibrio punensis, belonging to the Orientalis clade, also contains the toxigenic genes that cause AHPND in shrimp [15].…”

pirABvp-Bearing Vibrio parahaemolyticus and Vibrio campbellii Pathogens Isolated from the Same AHPND-Affected Pond Possess Highly Similar Pathogenic Plasmids

“…Outbreaks of AHPND have been reported in recent years in Asia (such as China, Vietnam, Malaysia, Philippines, Thailand) and Latin America (such as Mexico) (Gomez-Gil et al, 2014; Gomez-Jimenez et al, 2014; Kondo et al, 2014, 2015; Nunan et al, 2014; Yang et al, 2014; de la Pena et al, 2015; Lee et al, 2015; Soto-Rodriguez et al, 2015; Chonsin et al, 2016; Restrepo et al, 2016; Han et al, 2017). The disease has caused dramatic drops of shrimp production in affected areas, leading to an estimated loss of over $1 billion per year to the global shrimp farming industry (FAO, 2013).…”

Recombinant PirA‐like toxin protects shrimp against challenge with Vibrio parahaemolyticus, the aetiological agent of acute hepatopancreatic necrosis disease

“…; Chonsin et al . ). In this study, the effect of rPirA‐like toxin administration on mortality of shrimp challenged with V. parahaemolyticus AHPND was evaluated.…”