A newly identified protein complex that mediates white spot syndrome virus infection via chitin-binding protein

Abstract

White spot syndrome virus (WSSV) is a large enveloped virus which has caused severe mortality and huge economic losses in the shrimp farming industry. The enveloped virus must be combined with the receptors of the host cell membrane by the virus envelope proteins. In the case of WSSV, binding of envelope proteins with receptors of the host cell membrane was discovered in a number of previous studies, such as VP53A and 10 other proteins with chitin-binding protein (CBP), VP28 with Penaeus monodon Rab7, VP187 with β-integrin, and so on. WSSV envelope proteins were also considered capable of forming a protein complex dubbed an ‘infectome’. In this study, the research was focused on the role of CBP in the WSSV infection process, and the relationship between CBP and the envelope proteins VP24, VP28, VP31, VP32 VP39B, VP53A and VP56. The results of the reverse transcription-PCR analyses showed that CBP existed in a variety of shrimp. The speed of WSSV infection could be slowed down by inhibiting CBP gene expression. Far-Western blot analysis and His pull-down assays were conducted, and a protein complex was found that appeared to be composed of a ‘linker’ protein consisting of VP31, VP32 and VP39B together with four envelope proteins, including VP24, VP28, VP53A and VP56. This protein complex was possibly another part of the infectome and the possible binding region with CBP. The findings of this study may have identified certain points for further WSSV research.