Nucleotide and Predicted Amino Acid Sequences of the Marek's Disease Virus and Turkey Herpesvirus Thymidine Kinase Genes; Comparison with Thymidine Kinase Genes of Other Herpesviruses

AFRC Institute for Animal Health, Houghton Laboratory, Houghton, Huntingdon, Cambridgeshire PE17 2DA, U.K. In this paper we present the nucleotide sequences of the thymidine kinase (TK) genes of two avian herpesviruses: a highly oncogenic strain of Marek's disease virus (MDV strain RB1B) and its serologically related vaccine virus, the herpesvirus of turkeys (HVT strain Fc-126). The predicted coding regions of the two genes are 1029 and 1050 nucleotides respectively, corresponding to polypeptides of 343 and 350 amino acids in length. Putative nucleotide- and nucleoside-binding sites have been identified within the two predicted amino acid sequences. The MDV and HVT TK amino acid sequences exhibit 58.2% amino acid identity. Comparison with other available herpesvirus TK sequences reveals a greater homology to those of the alphaherpes-viruses than to those of the gammaherpesviruses. No overall homology was found when compared with the chicken cytoplasmic TK sequence. Keywords: nucleotide sequence, MDV, HVT, TK Received 3 May 1989; accepted 27 June 1989.