Sequence diversity of the infectious hypodermal and hematopoietic necrosis virus (IHHNV) in cultured shrimp populations in the Philippines

Partial sequence the capsid protein gene of a Philippine isolate of the infectious hypodermaland hematopoietic necrosis virus (IHHNV), a single-stranded DNA virus that infects both wild andcultured shrimps was identified. The obtained sequence shared 96-97% nucleotide identity with thecapsid protein gene of the other IHHNV isolates. Phylogenetic analyses showed that the capsid proteingene of the different IHHNV isolates did not cluster in terms of geographical location, indicating thewidespread distribution of the virus. Among the Philippine isolates, IHHNV apparently has high geneticdiversity. A sequence obtained from an IHHNV-infected shrimp postlarvae, Penaeus monodon in CentralPhilippines did not cluster with the other Philippine isolates and could represent a distinct isolate. Theresults of this study support the earlier findings that IHHNV has a high evolutionary rate, and given thisobserved phenomenon, strict monitoring of the movement of shrimps among geographic regions must beobserved to prevent the occurrence of future disease outbreaks due to this viral pathogen.