A neutralizing monoclonal antibody recognizes an 87K envelope glycoprotein on the murine cytomegalovirus virion.

An 87K glycoprotein (gp87) on the murine cytomegalovirus (MCMV) virion was immunoprecipitated by the neutralizing monoclonal antibody (MAb) 8D1.11A. The 87K glycoprotein is also radiolabeled in a surface iodination reaction, suggesting that it is exposed on the surface of the virion. Using a nondenaturing system of polyacrylamide gel electrophoresis in combination with Western blotting, we have shown that the epitope recognized by the MAb 8D1.11A resides on gp87. The failure of 8D1.11A to react with gp87 in a reduced and denatured form suggests that the epitope is recognized only when disulfide linkages are preserved. Our data also indicated that gp87 is present in the MCMV virion both in a monomeric form and as a component of disulfide-linked complexes. Using a two-dimensional gel electrophoresis system, we have demonstrated the presence of disulfide linkages between gp87 and virion polypeptides with apparent molecular weights of 138K, 46K, and 20K. Finally, the difference in migration rates of gp87 in SDS-polyacrylamide gels under reducing and nonreducing conditions suggests the existence of intramolecular disulfide bonds.