Involvement of serine proteinase in infectious pancreatic necrosis virus capsid protein maturation and NS proteinase cleavage in CHSE-214 cells

An investigation of virus-specific protein maturation in infectious pancreatic necrosis virus (IPNV) infected Chinook salmon embryo cells (CHSE-214) was undertaken. The precursor protein (pVP2‐1) of the major mature capsid protein (VP2) was processed sequentially from pVP2‐1 to pVP2‐ 2 and VP2. Experiments using serine proteinase inhibitors showed that the maturation of the VP2 was blocked in the pVP2‐1 post-translational cleavage steps. A protinin, a potent proteinase inhibitor, at 800 μ gm l ‐1 blocked pVP2‐2 to VP2 and the cleavage of VP4 (28 kDa) to VP4‐1 (25 kDa). Therefore, our data showed that the maturation of the capsid protein (VP2) and cleavage of VP4 (NS proteinase) can be blocked by serine proteinase inhibitors.