Identification of genes encoding two capsid proteins (VP24 and VP26) of herpes simplex virus type 1.

The capsid of herpes simplex virus type 1 is composed of seven proteins. VP5, VP19C, VP22a and VP23 have been shown previously to be the products of genes UL19, UL38, UL26.5 and UL18, respectively. The genes encoding VP21, VP24 and VP26 have not been identified to date. We have determined amino acid sequences of fragments of isolated capsid proteins generated by partial cleavage with CNBr. The results confirm the gene assignments for VP5, VP19C and VP23. They also show that VP26 is the product of gene UL35 and that VP24 contains the protease domain present in the N-terminal portion of the UL26-encoded protein. VP21 was not investigated, but we suggest that it is the C-terminal portion of the UL26-encoded protein remaining after release of VP24 and that it thus corresponds to a form of VP22a extended at the N terminus.