UL27.5 Is a Novel γ2 Gene Antisense to the Herpes Simplex Virus 1 Gene Encoding Glycoprotein B

An antibody made against the herpes simplex virus 1 U_S5 gene predicted to encode glycoprotein J was found to react strongly with two proteins, one with an apparent M_r of 23,000 and mapping in the S component and one with a herpes simplex virus protein with an apparent M_r of 43,000. The antibody also reacted with herpes simplex virus type 2 proteins forming several bands with apparent M_rs ranging from 43,000 to 50,000. Mapping studies based on intertypic recombinants, analyses of deletion mutants, and ultimately, reaction of the antibody with a chimeric protein expressed by in-frame fusion of the glutathione S-transferase gene to an open reading frame antisense to the gene encoding glycoprotein B led to the definitive identification of the new open reading frame, designated U_L27.5. Sequence analyses indicate the conservation of a short amino acid sequence common to U_S5 and U_L27.5. The coding sequence of the herpes simplex virus U_L27.5 open reading frame is strongly homologous to the sequence encoding the carboxyl terminus of the herpes simplex virus 2 U_L27.5 sequence. However, both open reading frames could encode proteins predicted to be significantly larger than the mature U_L27.5 proteins accumulating in the infected cells, indicating that these are either processed posttranslationally or synthesized from alternate, nonmethionine-initiating codons. The U_L27.5 gene expression is blocked by phosphonoacetate, indicating that it is a γ₂ gene. The product accumulated predominantly in the cytoplasm. U_L27.5 is the third open reading frame found to map totally antisense to another gene and suggests that additional genes mapping antisense to known genes may exist.