Identification of a vaccinia virus penetration protein.
A vaccinia virus structural protein responsible for infection was identified by monoclonal antibodies (mAb). Two mAbs (2D5 and 8C2) neutralized the virus at a dilution of about 10(5). The 2D5 mAb reacted with VP29K under standard immunoblotting conditions and with a 23-kDa protein when virus was dissociated under nonreducing conditions. The 8C2 mAb reacted with the 23-kDa protein, but not with VP29K. Two-dimensional electrophoresis demonstrated that the 23-kDa protein was the nonreduced form of VP29K. Since they possess the same N-terminal amino acid sequence, the protein was renamed VP23-29K. The gene that encoded it was HindIII A17L ORF. The VP23-29K-dependent process of infection did not occur during the adsorption phase at 4 degrees, and trypsin-treated virus could complete the process within 10 min at 37 degrees. One half of the trypsin-treated intracellular mature virus (IMV) achieved the process within 20 min, but for normal IMV this time period was 2 hr. VP23-29K had function for the early step of penetration, and the functional site in the nonreduced 23-kDa form was masked to some extent in normal virus. The late cell fusion by the fusion positive (F+) D1 mutant proceeded in neutral pH. Cells infected with F- IHD-J strain virus did not fuse, but a short treatment with pH 5 medium developed cell fusion. Both of the cell fusions were inhibited by the 2D5 and 8C2 mAbs. Virion VP23-29K was suggested to be the fusion protein for the early penetration and the late cell fusion phases of vaccinia infection cycle.
Department of Virology, Faculty of Medicine, Niigata University, Japan.
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Ichihashi
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Takahashi
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Oie
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D000956:Antigens, Viral / Q000276:immunology*; D002459:Cell Fusion; D005814:Genes, Viral; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D010084:Oxidation-Reduction; D014616:Vaccinia virus / Q000276:immunology / Q000472:pathogenicity*; D014760:Viral Fusion Proteins / Q000737:chemistry / Q000276:immunology*; D015678:Viral Structural Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000956:Antigens, Viral; D014760:Viral Fusion Proteins; D015678:Viral Structural Proteins