Hemadsorptive activity of transfected COS-7 cells expressing BHV-1 glycoprotein gIII

Bovine herpesvirus 1 (BHV-1) glycoprotein gIII plays an important role in virus adsorption. The SR alpha promoter expression vector containing BHV-1 gIII gene was transfected into COS-7 cells. Fluorescent antibody staining using a panel of monoclonal antibodies demonstrated antigenic authenticity with regard to at least three nonoverlapping neutralization sites as well as surface expression of the glycoprotein. C57BL mouse erythrocytes were found to absorb onto the gIII-expressing cells. The hemadsorbing activity was specifically inhibited by the monoclonal antibody blocking virus adsorption. Heparin, analog of cellular receptor for BHV-1, also prevented the erythrocytes from adsorbing to the cells and heparinase-treated erythrocytes showed no adsorption. These findings indicate that the gIII binds to the erythrocytes and probably to the host cells independently of other viral components.