Baculovirus expression and processing of tomato spotted wilt tospovirus glycoproteins

The open reading frame encoding the polyprotein precursor to the tomato spotted wilt tospovirus (TSWV) G1 and G2 glycoproteins was cloned as cDNA and used to produce a recombinant baculovirus. Protein expression was monitored in recombinant baculovirus-infected Spodoptera frugiperda IPLB-SF21 (SF21) cells with monoclonal antibodies raised to TSWV G1 and G2. Western blot analysis demonstrated expression, proteolytic processing, and glycosylation of the G1G2 polyprotein to yield proteins with serological specificities and electrophoretic mobilities similar to the G1 and G2 proteins found in TSWV virions. Indirect immunofluorescence localization of G1 and G2 in infected SF21 cells revealed accumulation of the glycoproteins in the plasmalemma. These experiments establish that the glycoproteins of TSWV, a plant-infecting virus in the family Bunyaviridae, can be processed in the absence of other viral proteins.