RNA editing-like phenomenon in paramyxovirus V gene mRNA observed in insect cells infected with a recombinant baculovirus

The V gene of the paramyxovirus human parainfluenza virus type 2 (hPIV2) is transcribed into both V and P mRNA, The V mRNA is a faithful transcript of the V gene; however, the P mRNA is transcribed by an RNA-editing mechanism in hPIV2-infected mammalian cells. Recombinant baculoviruses (rBV) were co nstructed containing the wild-type V gene, which has seven G residues at it s editing site, and a manipulated V gene with ten G residues at its editing site, A small amount of the P protein was synthesized, in addition to the V protein, when the wild-type V gene was expressed in rBV-infected insect c ells. Furthermore, synthesis of the P protein increased when rBV containing the manipulated V gene was used to infect insect cells. Both the P and V p roteins were detected after in vitro translation of mRNA from rBV-infected cells. Moreover, G-residue insertions and a deletion were detected in mRNA, Since the P protein was not detected after in vitro translation of V RNA t hat had been transcribed in vitro by T7 RNA polymerase, these results sugge st that the non-encoded G residues were inserted and deleted during transcr iption in insect cells. This RNA editing-like phenomenon and the implicatio ns of the length of the G cluster are discussed.