Three monoclonal antibodies were characterized by examining their reactivity to human cytomegalovirus (HCMV) glycoproteins under reducing and nonreducing conditions and their reactivity to glycoproteins and disulfide-linked glycoprotein complexes isolated by ion-exchange high-performance liquid chromatography. One monoclonal antibody, 9E10, reacted with glycoprotein complexes which had molecular weights of 93,000 and 450,000 and eluted from the ion-exchange column at 0.3 and 0.9 M NaCl, respectively. All glycoproteins associated in these complexes could be immunoprecipitated under reducing conditions by 9E10, suggesting that they were related to one another. The most abundant glycoproteins immunoprecipitated by 9E10 had molecular weights of 50,000 to 52,000. In contrast to this antibody, two other monoclonal antibodies, 9B7 and 41C2, reacted with glycoprotein complexes which had molecular weights of 130,000 and >200,000 and eluted from the ion-exchange column at 0.6 M NaCl. All glycoproteins associated in these complexes could be immunoprecipitated by 9B7 or 41C2 under reducing conditions, suggesting that they were also related to one another. The most abundant glycoprotein immunoprecipitated by 41C2 or 9B7 had a molecular weight of 93,000. In addition, it was also determined that a 93,000-molecular-weight glycoprotein which was not associated with other glycoproteins by disulfide bonds could not be precipitated by any of the three antibodies, suggesting that it was different from the other glycoproteins. The monoclonal antibodies were also examined for specificity and neutralizing activity. Monoclonal antibodies 41C2 and 9B7 were specific to HCMV as determined by immunofluorescent staining of skin fibroblast cells infected with several different viruses. However, 41C2 did not neutralize Towne strain HCMV, while 9B7 did. The neutralizing activity of 9B7 did require compliment. These results suggested that 41C2 and 9B7 reacted with different antigenic sites on the same glycoproteins. Unlike 41C2 and 9B7, monoclonal antibody 9E10 was found to cross-react with adenovirus and herpes simplex virus as determined by immunofluorescent staining of infected skin fibroblast cells. Furthermore, 9E10 neutralized the Towne and Toledo strains of HCMV in the absence of complement.

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Several murine monoclonal antibodies (MoAbs) were made to a family of human cytomegalovirus (HCMV) disulfide linked glycoprotein complexes designated gC-II. Characterization of these MoAbs by immunological methods showed that they could be divided into two groups recognizing different glycoproteins. Western blot analysis was done with immunoaffinity purified gC-II complexes. Under non-reducing conditions MoAbs from both groups recognized gC-II complexes with molecular weights of 67-93 k and 130 k to greater than 200 k. When purified gC-II complexes were reduced and individual glycoproteins separated by SDS-PAGE prior to Western blotting, Group 1 MoAbs reacted with glycoproteins having molecular weights of 47-63k, while Group 2 MoAbs reacted with glycoproteins having molecular weights of 39-48k and 90k to greater than 200k. Thus, gC-II complexes contain glycoproteins recognized by both groups of MoAbs. By Coomassie blue staining and incorporation of [3H]Arg, Group 1 glycoproteins appeared to be minor components in the complexes relative to Group 2 glycoproteins. Surface labeling of extracellular virus with galactose oxidase and tritiated borohydride showed that gC-II complexes of all molecular weights were on the surface of the virus. However, the most heavily labeled gC-II glycoproteins had molecular weights of 47-63k. These data confirm our previous observations that the gC-II complexes of HCMV are comprised of a heterogeneous family of glycoproteins.