Pseudorabies virus immediate-early regulatory protein IE180 expressed by recombinant baculovirus is functional

IE180, an immediate-early regulatory protein of pseudorabies virus, is required to activate viral early and late genes and is essential for viral growth. We constructed a recombinant baculovirus expressing IE180 in SF21AE insect cells. IE180 expressed by the recombinant migrated on gels as a single band with a molecular weight of 180 kDa and reacted with anti-IE180 peptide serum in Western blotting assay. Immunofluorescence using anti-IE180 peptide antibody demonstrated the accumulation of IE180 in cytoplasm of SF21AE cells infected with the recombinant virus. The IE180 produced in the insect cells was introduced into mammalian Vero cells infected with a PrV mutant with deletion of the IE180 gene by a cell-fusion technique. The growth of the deletion mutant in the fused cells was confirmed by infective assay and immunodetection of the progeny virus. This indicates that the IE180 expressed by the recombinant baculovirus is functional as a transactivator.