Rhesus cytomegalovirus glycoprotein B of 854 aas and 3 TMSs, 1 N-terminal and 2 near the C-terminus of the protein. GpB is an envelope glycoprotein that forms spikes at the surface of virion envelope. It is essential for the initial attachment to heparan sulfate moieties of the host cell surface proteoglycans and is involved in fusion of viral and cellular membranes leading to virus entry into the host cell. Following initial binding to its host receptors, membrane fusion is mediated by the fusion machinery composed at least of gB and the heterodimer gH/gL. It may be involved in the fusion between the virion envelope and the outer nuclear membrane during virion egress (Yue et al. 2003).