Human Cytomegalovirus (HCMV) Capsid Assembly Protein Precursor,UL80.5,plays a key role in capsid assembly and formation during viral lytic infection.Yeast two hybrid screen experiments indicate that UL80.5 potentially interacts with human protein UBC9,an E2 enzyme that conjugates small ubiquitin-like modifier (SUMO).The interaction between UL80.5 and UBC9 was further confirmed by co-immunoprecipitation from protein extracts isolated from human cells expressing both UL80.5 and UBC9.