THE UNIQUE SEQUENCE OF THE HERPES-SIMPLEX VIRUS-1 L COMPONENT CONTAINS AN ADDITIONAL TRANSLATED OPEN READING FRAME DESIGNATED UL49.5

We present evidence for the existence of an additional herpes simplex virus 1 gene designated U(L)49.5. The sequence, located between genes U(L)49 and U(L)50, predicts a hydrophobic protein with 91 amino acids. Attempts to delete U(L)49.5 were not successful. To demonstrate that U(L)49.5 is expressed, we made two recombinant viruses. First, we inserted in frame an oligonucleotide encoding a 15-amino-acid epitope known to react with a monoclonal antibody. This gene, consisting of the authentic promoter and chimeric coding domain, was inserted into the thymidine kinase gene of wild-type virus and in infected cells expressed a protein which reacted with the monoclonal antibody. The second recombinant virus contained a 5' U(L)49.5-thymidine kinase fusion gene. The protein expressed by this virus confirmed that the first methionine codon of U(L)49.5 served as the initiating codon. The predicted amino acid sequence of U(L)49.5 is consistent with the known properties of NC-7, a small capsid protein whose gene has not been previously mapped. A homolog of U(L)49.5 is present in the genome of varicella-zoster virus, located between homologs of U(L)49 and U(L)50.