The nucleotide sequence of the glycoprotein gB gene of infectious laryngotracheitis virus: analysis and evolutionary relationship to the homologous gene from other herpesviruses.

A 3698 bp region of the genome of infectious laryngotracheitis virus (ILTV) was sequenced and found to contain the entire glycoprotein gB gene and the C-terminal region of a gene homologous to the ICP 18.5 protein gene of herpes simplex virus type 1. The ILTV gB gene encoded a protein with an Mr of 100K possessing all the characteristics of a transmembrane glycoprotein. Alignment of the ILTV gB sequence with homologous sequences from six other herpesviruses revealed that 10 cysteine residues on the surface of the molecule were completely conserved and that the positions of several N-linked glycosylation sites were largely conserved. Evolutionary trees based on the gB amino acid sequences from a total of 13 herpesviruses were constructed and the relationships among these herpesviruses were examined.