Design And Evaluation Of A Novel Protein Vaccine For The Precaution Of White Spot Syndrome Virus (WSSV) Infection

White spot syndrome virus (WSSV) occurs worldwide and causes high mortality and considerable economic damage to the shrimp farming industry. No adequate treatments against this virus are available as the mechanisms of virus attachment and entry into shrimp cells are poorly understood. Recent research has indicated that VP37 is one of the virus attachment proteins of WSSV,and further indicated that the cell attachment 'Arg-Gly-Asp' (RGD) motif in VP37 can bind to shrimp cells and help the virus enter the cytoplasm. Therefore it is important to analyze and express the small peptide that is a segment of the VP37 which contains RGD motif,with the purpose of determining whether it can be treated as a novel protein vaccine used for the prevention of shrimp's infection. In this study, VP37 was digested with papain, and the peptide including RGD motif was found to have bioactivity. Consequently, a segment of VP37 (VP37p) was expressed in Escherichia coli. Binding assay by ELISA and fluorescence microscopy in vitro showed that VP37p is capable of binding to shrimp cells. Neutralization experiments in vitro and vaccination experiment in vivo showed that the VP37p can partly block the WSSV infection. The results of vaccination trials showed a significantly higher survival rate in shrimp vaccinated with rVP37p (57.9 %-74.1 %) when compared to control groups (100% mortality). The immunological parameters analyzed in the vaccinated and control groups revealed that the vaccinated shrimp showed significantly high level of prophenoloxidase and superoxide dismutase (SOD) when compared to the control groups. These experiments open up new ways to benefit the WSSV-hampered shrimp farming industry.