Nucleotide sequence of bovine herpesvirus type 1 glycoprotein gIII, a structural model for gIII as a new member of the immunoglobulin superfamily, and implications for the homologous glycoproteins of other herpesviruses.

The gene encoding bovine herpesvirus type 1 (BHV-1) glycoprotein gIII was mapped, cloned, and sequenced. The gene is situated between map units 0.122 and 0.135 and encodes a predicted protein of 521 amino acids. The identity of the sequenced gene has been verified previously by expression of immunologically authentic recombinant BHV-1 gIII (Fitzpatrick et al. (1988) J. Virol. 62, 4239-4248). Comparison of the BHV-1 gIII amino acid sequence with the homologous glycoproteins of other alphaherpesviruses revealed significant homology in the carboxy-terminal half of the molecules, including six invariant cysteine residues. A 96 amino acid domain with significant homology to class II major histocompatibility complex (MHC) antigen constant domains was identified in the conserved carboxy-terminal half of BHV-1 gIII. This domain is flanked by two other similarly sized domains which may be related to other immunoglobulin (Ig) superfamily domains. These homologies support a model for the structure of BHV-1 gIII as a new member of the Ig superfamily. Elements of the model may be applicable to the homologous glycoproteins of other herpesviruses and relevant to the immunobiology of herpesvirus infections.