Identification of a potential Marek's disease virus serotype 2 glycoprotein D gene with homology to herpes simplex virus glycoprotein D.

The gene of Marek's disease virus (MDV) serotype 2 (MDV2) homologous to glycoprotein D (gD) of herpes simplex virus (HSV) was identified and characterized by its nucleotide and predicted amino acid sequences. The MDV2 gD homologous gene contains an open reading frame capable of specifying a polypeptide of 385 amino acids, which include N- and C-terminal hydrophobic domains consistent with signal and anchor regions, respectively, and two potential N-linked glycosylation sites, one of which was located in a highly conserved region when compared to MDV serotype 1 (MDV1) and herpesvirus of turkeys (HVT). By northern blot analysis using a MDV2 gD-specific DNA probe, two highly abundant polycistronic 6.0 and 4.2 kb transcripts were detected in MDV2-infected cells. The genes encoding MDV2 protein kinase (PK), gD, and glycoprotein I (gI) homologues are transcribed to form 3' coterminal mRNAs of 6.0 kb (encoding PK, gD and gI) and 4.2 kb (encoding gD and gI), respectively. By using rapid amplification cDNA end (RACE) method, several RNA start sites, to be thought those of the 4.2 kb mRNA, were detected in the upstream of MDV2 gD homologue.