Advances in Research of Necrotizing Hepatopancreatitis Bacterium (NHPB) Affecting Penaeid Shrimp Aquaculture

Abstract

Necrotizing hepatopancreatitis (NHP) is a severe bacterial disease affecting penaeid shrimp aquaculture. NHP is caused by the gram-negative, pleomorphic, obligately intracellular NHP-bacterium (NHPB) that targets the hepatopancreas tissue of shrimp. NHPB is classified as an α -proteobacterium and is related to members of the Rickettsia. First reported in 1985 in a Texas shrimp farm, NHP has since affected shrimp farming in several North and South American countries, causing mortalities up to 95% and devastating economic losses to aquaculture crops. Because NHPB remains unculturable through traditional in vitro methods, the development of an in vivo cultivation system of NHPB in susceptible, specific pathogen-free Litopenaeus vannamei has allowed advancement of experimental research, including NHPB population biology and transmission dynamics. Current research on NHPB is discussed relative to management strategies of NHP disease in a shrimp pond. Compared to other important shrimp pathogens, NHPB is geographically limited, like that of yellowhead virus (YHV), but in contrast to the global distribution of Taura syndrome virus (TSV) and white spot syndrome virus (WSSV). Additionally, NHPB is less virulent than TSV and WSSV, and the transmission dynamics of TSV and YHV are much more complicated than that of NHPB and WSSV in penaeid shrimp.