Reemergence of Decapod Hepanhamaparvovirus (DHPV) remains as a major concern due to its global distribution, broad host range, and association with severe hatchery mortalities. DHPV was originally listed and later delisted as a notifiable disease by the World Organization for Animal Health (WOAH, Paris, France) in 2012. But the recent emergence of a novel genotype has raised renewed concerns over diagnostic failures and underestimated prevalence. This project assessed the diversity of DHPV genotypes worldwide since 1995 and developed a highly sensitive real-time PCR assay using a minor groove binding (MGB) probe capable of detecting all circulating genotypes.
DHPV is a single-stranded, DNA virus belonging to the family Parvoviridae. Analysis of historical data of diagnostic case reports (N=134, 19 countries) from 1995 to 2024 revealed a broad host range including many penaeid shrimp and freshwater prawn; difference in tissue tropism (hepatopancreas and midgut); and severity of histopathological lesions. DHPV produces highly basophilic, intranuclear inclusion bodies primarily in hepatopancreatic tubular epithelial cells and, occasionally in the midgut epithelium, contradicting the earlier view that infection is restricted to the hepatopancreas (Fig. 1).
Four primer sets [two for conventional PCR (NS1 and NS2) and two for real-time PCR (MGB and TaqMan probes)] based on consensus sequence of NS1 and NS2 genes were used in PCR assay. Total genomic DNA isolated from representative DHPV positive (by histopathology), archived paraffin-embedded histological tissue blocks (30 out of 134 cases) were used for the assays. Amplification of an internal control gene, EF-1α enabled assessment of DNA integrity. The DHPV amplification results were compared to determine the best primer set (Table 1). Among the primer/probe sets evaluated, only MGB probe-based assay detected all circulating genotypes. By integrating molecular detection with archived histopathological data of a global panel of samples, this study establishes a robust framework for a rapid and highly sensitive method for DHPV surveillance, thereby enhancing biosecurity essential for sustainable shrimp aquaculture.