The complete, known DNA sequence of HSV types 1 and 2 are approximately 160 kb and encodes about 85 genes, each of which encodes at least one protein.  Unknown are the immunological epitopes within these proteins, each epitope approximately 9-12 amino acids in length, that are capable of eliciting an effective T cell immune response to viral infection. 
Cellular immune responses are required to limit the severity of recurrent HSV infection in humans.  HSV-specific CD4 T cells can be cytotoxic towards virally-infected cells (M. Yasukawa et al.,  1991, J. Immunol.,  146:1341-1347; M. Yasukawa et al.,  1984, J. Immunol.,  133:2736-42).  HSV-specific T cells can also reduce the titer of HSV replication in HSV-infected, HLA-matched cells, produce lymphokines with antiviral or immunomodulatory activity, or provide specific B cell help to augment antiviral antibody responses.  References relating to the antigenic specificity of HSV-specific T cells include: A. G. Langenberg et al.,  1995, Ann.  Int.  Med.  122:889-898; A. Mikloska et al.,  1998, J. Gen. Virol.,  79:353-361; J. W. Torseth et al.,  1987, J. Virol.,  61:1532-1539; M. Yasukawa et al.,  1985, J. Immunol.,  134:2679-2687. 
There remains a need to identify specific epitopes capable of eliciting an effective immune response to HSV infection.  Such information can lead to the identification of more effective immunogenic antigens useful for the prevention and treatment of HSV infection.