The UL36 open reading frame (ORF) encodes the largest herpes simplex virus type 1 (HSV-1) protein, a 270-kDa polypeptide designated VP1/2, which is also a component of the virion tegument. A null mutation in the UL36 gene of herpes simplex virus type 1 results in accumulation of unenveloped DNA-filled capsids in the cytoplasm of infected cells. This family only covers a small central part of this large protein.