Identification and characterization of a novel strain of Decapod hepanhamaparvovirus in black tiger shrimp (Penaeus monodon) from Madagascar that does not cause histological lesions

Abstract

Decapod hepanhamaparvovirus (DHPV) is a single-stranded DNA virus that primarily affects the early life stages of penaeid shrimp, potentially leading to significant losses in hatchery operations. In an interesting finding, we observed that a small portion Black tiger shrimp (Penaeus monodon) originating from Madagascar harbored DHPV even in the absence of any discernible clinical signs. Detailed histopathological analysis of P. monodon post-larvae individuals revealed an absence of distinctive histological lesions typically associated with DHPV infection. However, sensitive molecular techniques, including PCR and real-time PCR and reverse transcriptase quantitative PCR (RT-qPCR) confirmed the presence of viral DNA and DHPV encoded transcripts in these specimens. The complete genome sequence of this newfound viral isolate, spanning 6254 nucleotides, showed a 96.9% nucleotide sequence similarity to a previously documented DHPV strain also originating from Madagascar. Moreover, it exhibited a genetic resemblance of 80.7% to 88.2% when compared to DHPV strains from other geographical regions. These findings underscore the unique genomic and histological characteristics of this novel DHPV isolate. This knowledge proves to be of paramount significance for the screening of broodstock and post-larvae in captive breeding programs, as it aids in identifying the presence of DHPV. Furthermore, it paves the way for future investigations into unraveling the precise role of viral-encoded proteins in shaping the clinical and histological manifestations of DHPV infections.