We expressed the bovine herpesvirus 1 (BHV-1) glycoprotein IV (gIV) in bovine cells. The protein expressed was identical in molecular mass and antigenic reactivity to the native gIV protein but was localized in the cytoplasm. Expressing cells were partially resistant to BHV-1, herpes simplex virus, and pseudorabies virus, as shown by a 10to 1,000-fold-lower number of plaques forming on these cells than on control cells. The level of resistance depended on the level of gIV expression and the type and amount of challenge virus. These data are consistent with previous reports by others that cellular expression of the BHV-1 gIV homologs, herpes simplex virus glycoprotein D, and pseudorabies virus glycoprotein gp5O provide partial resistance against infection with these viruses. We have extended these findings by showing that once BHV-1 enters gIVexpressing cells, it replicates and spreads normally, as shown by the normal size of BHV-1 plaques and the delayed but vigorous synthesis of viral proteins. Our data are consistent with the binding of BHV-1 gIV to a cellular receptor required for initial penetration by all three herpesviruses and interference with the function of that receptor molecule.

SUMMARYWe expressed the bovine herpesvirus type 1 (BHV-1) glycoproteins, gI and gIII, in bovine cells using a bovine papillomavirus vector. The proteins expressed by these cells had the same Mr as the native BHV-1 proteins and monoclonal antibodies detected no differences in their antigenic structure. Cells expressing gI were infected with either BHV-1 or herpes simplex virus type 1 (HSV-1). The number of plaques in gI-expressing cells was similar to that seen with normal fibroblasts infected with BHV-1 or HSV-1. However, BHV-1 or HSV-1 plaques produced in gI-expressing cells were smaller and darker than those seen in normal fibroblasts indicating an interference with cell-to-cell transmission or cellular lysis. Virus growth curves and [3SS]methionine labelling of BHV-l-infected gI-expressing cells showed no difference in virus production, virus protein synthesis or cellular protein shutdown when compared to BHV-l-infected normal cells. This led us to conclude that the gI protein may interfere with a cellular protein(s) responsible for the cytopathic effects of BHV-1 infection. Cells expressing gIII were fully susceptible to BHV-1 infection.

SUMMARY: A method is described for expressing bovine herpes virus-1 {BHV-I~ glyeoproteins gI and gIII in eukaryotic cells. These cells are prepared by transfection with plasmids containing the BHV-1 glycoprotein genes. The BHV-1 glycoproteins from these expressing cells as well as from BHV-1 infected cells can be purified by monoclonal antibody affinity chromatography. The BHV-1 expressing cells can be used as targets in immunologic assays and the affinity-purified glycoproteins are suitable for use in in vitro immunologic assays or as immunogens to induce virus neutralizing antibodies.

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