PmAV, a novel gene involved in virus resistance of shrimp Penaeus monodon

Diseases caused by viruses especially by white spot syndrome virus (WSSV) are the greatest challenge to worldwide shrimp aquaculture. The innate immunity of shrimp has attracted extensive attention, but no factor involved in the virus resistance has been reported. Here we report for the first time the identification of an antiviral gene from shrimp Penaeus monodon. A differential cDNA (designated as PmAV) cloned from virus-resistant shrimp P. monodon by differential display (DD) was found to have an open reading frame (ORF) encoding a 170 amino acid peptide with a C-type lectin-like domain (CTLD). The PmAV gene was expressed in Escherichia coli and the protein was purified. Recombinant PmAV protein displayed a strong antiviral activity in inhibiting virus-induced cytopathic effect in fish cell in vitro. Moreover, native PmAV protein was isolated from shrimp hemolymph by immuno-affinity chromatography and confirmed by Western blot. No agglutination activity was observed both in recombinant and native PmAV protein. Immunohistological study showed that PmAV protein was located mainly in the cytoplasm, and not bound to the shrimp WSSV. It implies that the antiviral mechanism of PmAV protein is not by inhibiting the attachment of virus to target host cell. The discovery of PmAV gene might provide a clue to elucidate the innate immunity of marine invertebrates and would be helpful to shrimp viral disease control.