Identification of a collagen-like protein gene from white spot syndrome virus

The most unique feature of white spot syndrome virus (WSSV) is the presence of a collagen-like protein (termed as WSSV-CLP). In this report, the N-terminal fragment of WSSV-CLP (CLPn) was expressed as a fusion protein with glutathione S-transferase (GST) in Escherichia coli and purified. Specific antibody was then raised against the purified fusion protein (GST-CLPn). Temporal analysis showed that the WSSV collagen gene was an early viral gene. Immunogold localization using specific antibody revealed that the gold particles, under a transmission electron microscope, were presented along the outer envelope of WSSV virions. This experiment suggested that the collagen gene encoded an envelope protein of WSSV. Using immuno-affinity chromatography, the WSSV-CLP was purified from crudely purified WSSV virions. The WSSV-CLP was N-glycosylated, as indicated by the increased migration in SDS-PAGE after treatment with N-linked glycosidase F.