Decapod penstylhamaparvovirus 1, commonly known as infectious hypodermal and hematopoietic necrosis virus (IHHNV), remains an economically important viral pathogen for penaeid shrimp aquaculture. Since the initial report of the virus in 1982, the virus has spread in all major shrimp farming regions of the world. The World Organisation for Animal Health (WOAH, Paris, France) recommended methods for the detection of IHHNV include both conventional and real-time PCR. However, published reports and anecdotal evidence suggest the occurrence of non-specific amplifications when testing for IHHNV using the WOAH protocols. The accurate detection of IHHNV was further complicated when a viral genomic fragment was found to be integrated with the host genome as an endogenous virus element (EVE).
Studies were designed to develop a sensitive, robust TaqMan PCR method for detection of IHHNV in the three commercially important penaeid shrimp: Penaeus vannamei, P. monodon and P. stylirostris; and the method can differentiate between the infectious form of IHHNV and the EVE. We compared the performance of the WOAH-recommended real-time PCR method to several published as well as in-house designed primer/probe sets spanning the entire genome of IHHNV. Our results show that (1) more than one primer/probe set is needed when testing for the infectious form of IHHNV in all three species of shrimp; and (2) primers/ probe: qIH-Fw and qIH-Rv/3072-IH-Probe, and 3144F and 3232R/ 3187-IH-Probe have diagnostic characteristics that would enable IHHNV detection in all three shrimp species with high diagnostic specificity and sensitivity. These findings are valuable for large-scale screening of shrimp using a TaqMan real-time PCR assay.
Key words: infectious hypodermal and hematopoietic necrosis virus, IHHNV, shrimp, endogenous virus element, EVE.