The gene encoding the glycoprotein H (gH) homologue of CMV strain Towne was cloned, sequenced, and expressed. The predicted 742 amino acid gH protein had characteristics typical of a membrane glycoprotein including hydrophobic signal and transmembrane domains and six possible N-linked glycosylation sites. The CMV (Towne) gH gene had a 95% nucleotide identity and a 96.6% amino acid identity with the CMV (AD169) gH gene, as described by M. P. Cranage, G. L. Smith, S. E. Bell, H. Hart, C. Brown, A. T. Bankier, P. Tomlinson, B. G. Barrell, and T. C. Minson (1988, J. Virol. 62, 1416-1422). Transcriptional analysis of the gH gene revealed that the 2.9-kilobase (kb) gH transcript was not detected until late after CMV infection, indicating that the kinetics of gH expression were typical of the late class of CMV genes. The gH gene was expressed in COS cells using a vector in which transcription was driven by the SV40 early promoter. The expression of gH was detected by immunofluorescence using the virus neutralizing murine monoclonal antibody 1G6, which is specific for an 86-kilodalton (kDa) CMV virion membrane protein (p86). Amino acid sequence analysis of p86 tryptic peptides revealed sequence identity with peptides from the deduced gH amino acid sequence, confirming that the gH gene encodes p86. These results indicate that CMV gH can induce virus neutralizing antibodies and establishes gH as a candidate antigen for a subunit vaccine against CMV.