Comprehensive characterization of interaction complexes of herpes simplex virus type 1 ICP22, UL3, UL4, and UL20.5

It has been reported that herpes simplex virus type 1 UL3, UL4, and UL20.5 proteins are localized to small, dense nuclear bodies together with ICP22 in infected cells. In the present study, we comprehensively characterized these interactions by subcellular colocalization, coimmunoprecipitation, and bimolecular fluorescence complementation assays. For the first time, it was demonstrated that both UL3 and UL20.5 are targeted to small, dense nuclear bodies by a direct interaction with ICP22, whereas UL4 colocalizes with ICP22 through its interaction with UL3 but not UL20.5 or ICP22. There was no detectable interaction between UL3 and UL20.5.