Human herpesvirus 6 U11 protein is critical for virus infection.

All herpesviruses contain a tegument layer comprising a protein matrix; these proteins play key roles during viral assembly and egress. Here, liquid chromatography and tandem mass spectrometry analysis (LC-MS/MS) of proteins from human herpesvirus 6 (HHV-6)-infected cells revealed a possible association between two major tegument proteins, U14 and U11. This association was verified by immunoprecipitation experiments. Moreover, U11 protein was expressed during the late phase of infection and incorporated into virions. Finally, in contrast to its revertant, a U11 deletion mutant could not be reconstituted. Taken together, these results suggest that HHV-6 U11 is an essential gene for virus growth and propagation.