Probably acts as a viral splicing factor that regulates viral RNA splicing. Functions as a multifunctional regulator of the expression of viral lytic genes (By similarity). Early protein that promotes the accumulation and nuclear export of viral intronless RNA transcripts by interacting with mRNAs and cellular export proteins. Homodimer. Homodimerization is required for transactivation (By similarity). Interacts with host ALYREF and with mouse ALYREF2. Associates in a complex with RNA, and host export factors NXF1/TAP and ALYREF or ALYREF2; these interactions allow nuclear export of viral transcripts. Shuttles between the nucleus and the cytoplasm. Transactivated by ORF50 protein. Binds viral intronless RNAs; the RNA binding site overlaps partially with the binding site for host ALYREF or ALYREF2. ORF50 and ORF57 are the earliest genes expressed in the lytic cycle. Belongs to the HHV-1 ICP27 protein family.