The human cytomegalovirus UL94 open reading frame encodes a conserved herpesvirus capsid/tegument-associated virion protein that is expressed with true late kinetics.

In this report, we provide a detailed characterization of the human cytomegalovirus (HCMV) UL94 gene product. Northern (RNA) blot analysis of infected cell RNA demonstrated that UL94 message was found only at late times of infection and was not synthesized in the presence of the viral DNA replication inhibitor ganciclovir. Expression of the UL94 open reading frame in vitro and in vivo yielded a protein with the predicted molecular mass of 36 kDa. A monoclonal antibody raised to a UL94-specific peptide reacted specifically with a 36-kDa protein in HCMV-infected fibroblasts. This protein was found only at late times of infection and was also present in purified HCMV virions. Fractionation of purified virions and HCMV-infected cells revealed an association of UL94 immunoreactivity with the capsid/tegument and nuclear fractions, respectively. The evolutionary conservation of UL94 protein sequence and an analysis of potential functional regions of the protein are discussed.