GLYCOPROTEIN E2 OF CLASSICAL SWINE FEVER VIRUS - EXPRESSION IN INSECTCELLS AND IDENTIFICATION AS A RIBONUCLEASE

Two regions of amino acids homologous to the ribonuclease catalysis do main of the fungal RNases T-2 of Aspergillus oryzae and Rh of Rhizopus niveus and the plant S-glycoproteins of Nicotiana alata are perfectly conserved in the amino acid sequence of the envelope glycoprotein E2 of classical swine fever virus (CSFV). To analyze the functional signi ficance of these conserved sequences, the gene encoding E2 was inserte d into the p10 locus of baculovirus and expressed in insect cells. Rec ombinant virus BacCE2 generated a protein which was similar in size (4 2 to 46 kDa) to wild-type E2 synthesized in swine kidney cells infecte d with CSFV. Recombinant E2 was purified by immunoaffinity chromatogra phy from the lysate of cells infected with BacCE2 and assayed for RNas e activity. RNase activity coeluted with the E2 fraction, indicating t hat ribonuclease activity is an inherent property of E2. The ribonucle ase-specific activity of the protein fraction containing pure E2 was c omparable to that of the N. alata S-glycoproteins. (C) 1994 Academic P ress, Inc.