The herpes simplex virus (HSV) envelope glycoprotein gB is known to be highly immunogenic. Related glycoproteins, with conserved amino acid sequence, occur in members representative of all the herpesvirus subfamilies. In this work the immunogenicity of HSV-2 gB has been studied using molecular cloning techniques and in vivo and in vitro immuno-assays. A 4.7kbp fragment of HSV-2 representing 0.345-0.376 MU was shown to hybridise to an HSV-2 messenger RNA of 3.2kb. This translated in vitro to a polypeptide of 92kDa which comigrated on SDS PAGE with immunoprecipitated gB-2. A restriction map of the 4.7kbp DNA was subsequently shown to correspond to a published gB-2 gene sequence. Fragments of this DNA were expressed fused to β-galactosidase in E.coli by random cloning into the vector pXY460. A number of HSV-2 serologically positive clones were characterised by DNA sequencing. The gB-2 specific sequences expressed by three clones were unambiguously determined. Their respective fusion proteins were immunopurified by anti-β-galactosidase affinity chromatography. These antigens were assayed in vitro by lymphoproliferative responses and in vivo by delayed-type hypersensitivity and protection studies. Ag59, representing gB-2 codons 339-394, was the most antigenic and immunogenic of the recombinant antigens and provided 36% protection in a 10x LD50 lethal challenge
