Comparison of the sequence of the secretory glycoprotein A (gA) gene in Md5 and BC-1 strains of Marek's disease virus type 1.

DNA fragments containing the secretory glycoprotein A (gA) gene of Marek's disease virus type 1 (MDV1) were cloned from the DNA libraries of very virulent Md5 and virulent BC-1 strains and sequenced. Two open reading frames (ORF1 and ORF2) were identified for both strains. The ORF1 has the potential to code for a protein of 501 amino acids with a molecular weight of 56 kD that contains strong hydrophobic regions in both the amino and carboxyl termini, and nine potential N-linked glycosylation sites, while the ORF2 is capable of coding for a 24-kD protein. These results indicate that the ORF1 codes for the unprocessed form of gA. Between the Md5 and BC-1 strains, only two sequence mismatches exist in the DNA fragment. More differences appear to exist in the gA sequence of the MDV1 GA strain (12), which lacks a strong hydrophobic anchor sequence. Similarities between the predicted amino acid sequences of the MDV1 gA and the proteins of the other herpesviruses such as herpes simplex type I gC, pseudorabies virus gIII, and varicella zoster virus gpV were noted.