Vibrio parahaemolyticus and Vibrio harveyi causing Acute Hepatopancreatic Necrosis Disease (AHPND) in Penaeus vannamei (Boone, 1931) isolated from Malaysian shrimp ponds

• Published in: Aquaculture Vol. 511; p. 734227
• Main Authors: Muthukrishnan, Sarmila, Defoirdt, Tom, Ina-Salwany, M.Y., Yusoff, Fatimah Md, Shariff, Mohamed, Ismail, Siti Izera, Natrah, I.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-09-2019
• Subjects: Early mortality syndrome; Vibriosis; Whiteleg shrimp; Whiteleg shrimp; Early mortality syndrome; Vibriosis
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2019.734227

Acute hepatopancreatic necrosis disease (AHPND) first emerged as a new shrimp disease in 2009 that heavily affected shrimp industry leading to global economic losses. The etiological agent was previously identified as Vibrio parahaemolyticus that carries a plasmid containing toxins (PirA and PirB). However, recent researches revealed that V. parahaemolyticus is not the only bacterial species capable of causing AHPND, thus this study screened on bacterial strains with AHPND toxins from Penaeus vannamei shrimps in Malaysia. Out of the 86 isolated total strains, 12 AHPND positive strains were arbitrarily selected and were evaluated in in vivo assay using Artemia franciscana as a model organism. All the 12 AHPND positive strains with PirA and PirB genes demonstrated significant mortalities (P < 0.05) of A. franciscana compared to the negative control. The 12 AHPND positive strains were identified using molecular methods of 16S rRNA, RctB and RpoD region amplifications belonged to the Harveyi clade and were closely related to V. parahaemolyticus and Vibrio harveyi. Further test showed that the yellow colony V. harveyi strain BpShHep24 was found to be more virulent than the green colony V. parahaemolyticus strain BpShHep31 in shrimp P. vannamei challenge test. Histological examination of shrimp hepatopancreas challenged with yellow colony V. harveyi strain BpShHep24 showed massive sloughing of hepatopancreas tubules of epithelial cells into the lumen, haemocyte infiltrations, proximal-to-distal lesion of hepatopancreas and collapsed tubule epithelia within 24 h.
•Identification of Vibrio harveyi and V. parahaemolyticus causing AHPND with PirA and PirB genes in Malaysia.•16S rRNA solely is insufficient to identify Vibrio.•Multilcous sequencing analysis (MLSA) is a reliable tool for accurate identification of Vibrio species.•Yellow V. harveyi strain BpShHep24 is more virulent to whiteleg shrimp than green V. parahaemolyticus strain BpShHep31.•Farmers should not rely on colony colors on thiosulphate-citrate salt sucrose (TCBS) agar.