BOVINE HERPESVIRUS TYPE-1 GLYCOPROTEIN-H IS ESSENTIAL FOR PENETRATIONAND PROPAGATION IN CELL-CULTURE

Bovine herpesvirus type 1 (BHV-1) glycoprotein H (gH) is a structural component of the virion which forms a complex with glycoprotein gL. To study the role of BHV-1 gH in the virus infectious cycle, a gH null m utant was constructed in which the gH coding sequences were deleted an d replaced by the Escherichia coli lacZ cassette. The BHV-1 gH null mu tant was propagated in trans-complementing MDBK cells, stably transfec ted with plasmid pMEP4 containing the BHV-1 gH gene under the control of the inducible mouse metallothionein promoter. Experiments with the BHV-1 gH null mutant showed that gH is essential in the infectious cyc le of the virus and is specifically involved in virus entry and cell-t o-cell spread. The lack of infectivity of virions devoid of gH is not due to a defect in attachment. Moreover, PEG-induced fusion of virions to target cells provides evidence that BHV-1 gH is required for virio n penetration.