Vibrio parahaemolyticus Associated with Mass Mortality of Postlarval Abalone, Haliotis diversicolor supertexta (L.), in Sanya, China

Citation

Cheng L, Huang J, Shi C, Thompson K, Mackey B & Cai J (2008) Vibrio parahaemolyticus Associated with Mass Mortality of Postlarval Abalone, Haliotis diversicolor supertexta (L.), in Sanya, China. Journal of the World Aquaculture Society, 39 (6), pp. 746-757. https://doi.org/10.1111/j.1749-7345.2008.00210.x

Abstract
Outbreaks of mass mortality in postlarval abalone, Haliotis diversicolor supertexta (L.), have swept across south China since 2002 and in turn have resulted in many abalone farms closing. Twenty-five representative bacterial isolates were isolated from a sample of five diseased postlarval abalone, taken 15 d postfertilization during an outbreak of postlarval disease in Sanya, Hainan Province, China in October 2004. A dominant isolate, referred to as Strain 6, was found to be highly virulent to postlarvae in an experimental challenge test, with a 50% lethal dose (LD50) value of 3.2 ž 104 colony forming units (CFU)/mL, while six of the other isolates were weakly virulent with LD50 values ranging from 1 ž 106 to 1 ž 107 CFU/mL, and the remaining 18 isolates were classified as avirulent with LD50 values greater than 1 ž 108 CFU/mL. Using both an API 20E kit and 16S recombinant DNA sequence analysis, Strain 6 was shown to be Vibrio parahaemolyticus. It was sensitive to 4 and intermediately sensitive to 5 of the 16 antibiotics used when screening the antibiotic sensitivities of the bacterium. Extracellular products (ECPs) prepared from the bacterium were lethal to postlarvae when used in a toxicity test at a concentration of 3.77 mg protein/mL, and complete liquefaction of postlarvae tissues occurred within 24 h postexposure. Results from this study implicate V. parahaemolyticus as the pathogen involved in the disease outbreaks in postlarval abalone in Sanya and show that the ECPs may be involved in the pathogenesis of the disease.

Keywords
abalone; analysis; BACTERIA; BACTERIAL; challenge; China; Disease; fish; Haliotis diversicolor supertexta; Health; lethal; MASS MORTALITIES; mass mortality; MORTALITIES; MORTALITY; other; PATHOGEN; PRODUCT; PRODUCTS; SAMPLE; SEQUENCE; TISSUE; UNITS; VALUE; VALUES; Vibrio parahaemolyticus; welfare

Journal
Journal of the World Aquaculture Society: Volume 39, Issue 6