OBJECTIVE: p48 (ac103) gene is highly conserved in baculovirus, implying that p48 might play a fundamental role in the life cycle of baculovirus. We studied the expression of p48 gene of Autographa californica multiple nucleopolyhedrovirus (AcMNPV)--the type baculovirus species. METHODS: With Bac-to-Bac system, we constructed two p48 repair viruses, in which hemagglutinin (HA)-tag was fused to C-terminus and N-terminus of P48, respectively. To examine the effect on occlusion body morphogenesis and to facilitate examination of virus infection, the green fluorescence protein (gfp) gene and polyhedrin (polh) gene were also inserted into the recombinant viruses. Sf9 cells were transfected with each bacmid constructed, and the supernatants containing the budded viruses (BVs) were used to infect Sf9 cells. At the indicated time points, cells were harvested and used for SDS-PAGE and Western blot analysis. The expression of fusion protein was detected with the monoclonal antibody to the HA-epitope. RESULTS: Western blot analysis indicated that a specific 43 kDa protein was detected at 12 hours postinfection (hpi) and remained detectable up to 96 hpi in cells infected with p48 repair virus with HA-tag fused in C-terminus. Meanwhile, another protein of 26 kDa was also detected from 48 hpi to 96 hpi. However, no signals were detected in cells infected with p48 repair virus with HA-tag fused in N-terminus even at 96 hpi. CONCLUSION: p48 is a late gene and expressed in late infection. P48 might be cleaved in N-terminal when it is expressed in insect cells.
OBJECTIVE: p48 (ac103) gene is highly conserved in baculovirus, implying that p48 might play a fundamental role in the life cycle of baculovirus. We studied the expression of p48 gene of Autographa californica multiple nucleopolyhedrovirus (AcMNPV)--the type baculovirus species. METHODS: With Bac-to-Bac system, we constructed two p48 repair viruses, in which hemagglutinin (HA)-tag was fused to C-terminus and N-terminus of P48, respectively. To examine the effect on occlusion body morphogenesis and to facilitate examination of virus infection, the green fluorescence protein (gfp) gene and polyhedrin (polh) gene were also inserted into the recombinant viruses. Sf9 cells were transfected with each bacmid constructed, and the supernatants containing the budded viruses (BVs) were used to infect Sf9 cells. At the indicated time points, cells were harvested and used for SDS-PAGE and Western blot analysis. The expression of fusion protein was detected with the monoclonal antibody to the HA-epitope. RESULTS: Western blot analysis indicated that a specific 43 kDa protein was detected at 12 hours postinfection (hpi) and remained detectable up to 96 hpi in cells infected with p48 repair virus with HA-tag fused in C-terminus. Meanwhile, another protein of 26 kDa was also detected from 48 hpi to 96 hpi. However, no signals were detected in cells infected with p48 repair virus with HA-tag fused in N-terminus even at 96 hpi. CONCLUSION: p48 is a late gene and expressed in late infection. P48 might be cleaved in N-terminal when it is expressed in insect cells.