IDENTIFICATION AND CHARACTERIZATION OF MURINE GAMMAHERPESVIRUS-68 GP150 - A VIRION MEMBRANE GLYCOPROTEIN

Murine gammaherpesvirus 68 (MHV-68) is a naturally occurring virus of murid rodents which displays pathobiological characteristics similar t o those of other gammaherpesviruses, including Epstein-Barr virus (EBV ), However, unlike EBV and many other gammaherpesviruses, MHV-68 repli cates in epithelial cells in vitro and infects laboratory strains of m ice and therefore provides a good model for the study of gammaherpesvi ruses. Studies of sequences around the center of the MHV-68 genome ide ntified a gene (designated BPRF1 for BamHI P fragment rightward open r eading frame 1) whose putative product had motifs reminiscent of a tra nsmembrane glycoprotein, All other gammaherpesviruses have a glycoprot ein in this genomic position, but the BPRF1 gene showed sequence homol ogy with only the EBV membrane antigen gp340/220, Biochemical analysis showed that the product of BPRF1 was a glycoprotein present on the su rface of infected cells, and immunoelectron microscopy showed that it was present in the virus particle. in addition, antibodies to the BPRF 1 product raised by using a bacterial fusion protein neutralized the v irus in the absence of complement, The predominant molecular weights o f the protein were 150,000 and 130,000, Pulse-chase analysis and endog lycosidase-H digestion showed that the 130,000-molecular-weight form w as a precursor of the 150,000-molecular-weight form, and cell surface labelling showed that the 150,000-molecular-weight form alone was on t he cell surface, We therefore named the protein gp150, Since gp150 is the first virion-associated glycoprotein and neutralizing determinant of MHV-68 to be characterized, it provides a valuable tool for the fut ure study of virus-host interactions.