Proteins of bovine herpesvirus type 4 released into the culture medium of productively infected cells: identification of a 135K glycoprotein involved in viral attachment.

Three bovine herpesvirus type 4 (BHV-4) proteins released into the culture medium of infected cells were identified, with Mr values of 135K, 16K and 14.5K. Among these three proteins, two were precipitated by the monoclonal antibodies characterized in this work. One is a glycoprotein of 135K (gp8) which does not seem to be involved in BHV-4 neutralization. Moreover, this 135K glycoprotein adsorbed onto uninfected susceptible cells. The attachment of gp8 to cells was totally inhibited by the prior adsorption of unlabelled viral proteins. Moreover, anti-gp8 monoclonal antibodies were effective in inhibiting the adsorption of gp8. These results indicate that gp8 could be involved in BHV-4 attachment.