IDENTIFICATION AND MOLECULAR CHARACTERIZATION OF THE MURINE CYTOMEGALOVIRUS HOMOLOG OF THE HUMAN CYTOMEGALOVIRUS UL100 GENE

The UL100 gene of human cytomegalovirus (HCMV) has been shown to encod e an envelope glycoprotein that might play an important role in HCMV i nfection. Using the HCMV UL100 gene as a probe in low stringency hybri dization studies, we were able to identify the putative UL100 homologo us gene of murine cytomegalovirus (MCMV), strain Smith. The MCMV gene was sequenced and localized to the left end of the EcoRI fragment H on the MCMV physical map. This genomic location is similar to that found for the HCMV UL100 gene. The MCMV UL100 mRNA is 1.6 kb in size and is expressed exclusively in the late stages of infection. The 5' and 3' boundaries of the transcript were determined. The open reading frame ( ORF) of the UL100 gene could encode a protein of 371 amino acid residu es with a calculated molecular mass of 42 kDa. Computer analysis of th e deduced amino acid sequence of this gene predicted the presence of e ight transmembrane domains and four N-linked glycosylation sites in th e protein. Sequence comparison revealed that this putative protein sha res similarity with the predicted UL100 homologs of several other herp esviruses, and is most similar to the HCMV UL100 protein (47% identity ).