Nucleotide and predicted amino acid sequences of Marek's disease virus homologues of herpes simplex virus major tegument proteins.

The DNA sequence of an 8.4 kbp BamHI-EcoRI fragment of Marek's disease virus (MDV) strain GA was determined. Three of the predicted polypeptides are homologous to UL47, UL48 and UL49 encoding the major tegument proteins of herpes simplex virus type 1 (HSV-1), and four are homologous to HSV-1 UL45, UL46, UL49.5 and UL50. These seven genes are found in the long unique region of the MDV genome and are collinear with homologues in HSV-1 and varicella-zoster virus (VZV). Northern blot analysis revealed different transcriptional patterns from those of HSV-1 and VZV. MDV homologues of UL49.5, UL49 and UL47 lack a poly(A) signal immediately downstream of their coding regions. Amino acid conservation between MDV and HSV-1, and between MDV and VZV is as high as that between HSV-1 and VZV. The MDV homologue of UL48 shows 60% similarity to its HSV-1 counterpart. Amino acid sequence comparison reveals that the MDV homologue of UL48 lacks an acidic carboxyl terminus. This homologue, like the VZV homologue of UL48, may be involved in the trans-activation of immediate early genes and may function as an important component of the structural proteins.