LvCPG2 facilitated WSSV infection by interaction with VP26 and VP28.

Chondroitin sulfate proteoglycans (CSP), widely distributed in extracellular matrices, have several important functions in vertebrates. In certain viruses, CSP acts as a receptor to promote infection. However, chondroitin proteoglycans lack sulfate are poorly understood in invertebrates. In this study, chondroitin proteoglycan 2 of Litopenaeus vannamei (LvCPG2) was cloned. The open reading frame of LvCPG2 cDNA is 2133 bp, which encodes a protein of 710 amino acids. LvCPG2 contained eight Chitin-binding domain type 2 (ChtBD2). LvCPG2 had the highest expression in lymphoid and significantly increased after WSSV challenge. The relative expression of IE1 and VP28, as well as the viral copy numbers were decreased significantly in LvCPG2-silenced shrimp. The far-western blotting result showed that LvCPG2 interacted with VP26 and VP28. Molecular docking complexes showed that N-terminal of LvCPG2 interacted with C-terminal VP26, while C-terminal of LvCPG2 combined with N-terminal of VP28. Flow cytometry analysis indicated that LvCPG2 could facilitate WSSV adhesion and penetration of shrimp hemocytes. Collectively, these findings suggested that LvCPG2 was involved in WSSV infection by interaction with VP26 and VP28.