Herpes simplex virus type 1 capsid protein, VP21, originates within the UL26 open reading frame

Department of Molecular Genetics and Biochemistry, School of Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15261, U.S.A. The goal of experiments reported here was to identify the genes that encode capsid proteins VP21 and VP24 of herpes simplex virus type 1 (HSV-1). Capsids were isolated from infected cells and the proteins were separated by SDS-PAGE. N-terminal amino acid sequence analysis of partial CNBr digestion products, and of intact VP21, showed that it is encoded within the UL26 open reading frame (ORF) of HSV-1 beginning with codon 248 and probably extending to the end of the ORF (codon 635). Similar analysis of digestion products confirmed that VP24 is specified by codons 1 to 247 at the 5' end of the UL26 ORF. Each of the seven known capsid proteins has now been assigned to an ORF. Received 6 May 1993; accepted 11 June 1993.