Litopenaeus vannamei attenuates white spot syndrome virus replication by specific antiviral peptides generated from hemocyanin.

Recent studies have shown that hemocyanin plays immune-related functions apart from its canonical respiratory function. While shrimp hemocyanin is found to generate antimicrobial peptides, antiviral related peptides have not been reported. In the present study, the serum of white spot syndrome virus (WSSV) infected Litopenaeus vannamei analyzed by two-dimensional gel electrophoresis, revealed 45 consistently down-regulated protein spots and 10 up-regulated protein spots. Five of the significantly up-regulated spots were identified as hemocyanin derived peptides. One of the five peptides, designated LvHcL48, was further characterized by analyzing its primary sequence via Edman N-terminal sequencing, C-terminal sequencing and amino acid sequence alignment. LvHcL48 was found to be a 79 amino acid fragment (aa584-662) from the C-terminal domain of L. vannamei hemocyanin protein (ADZ15149). Both in vivo and in vitro functional studies revealed that LvHcL48 has immunological activities, as recombinant LvHcL48 protein (rLvHcL48) significantly inhibited the transcription of the WSSV genes wsv069 and wsv421 coupled with a significant reduction in WSSV copy numbers. Further analysis showed that LvHcL48 could interact with the WSSV envelope protein 28 (VP28). Our present data therefore reveals the generation of an antiviral hemocyanin derived peptide LvHcL48 from WSSV infected shrimp, which binds to the envelope protein VP28 of WSSV.