African swine fever virus thymidylate kinase gene: sequence and transcriptional mapping.

A putative thymidylate kinase gene of African swine fever virus has been identified at the left end of the SalI I' fragment of the virus genome. The gene, designated A240L, has the potential to encode a protein of 240 amino acids with an M(r) of 27,754 and is transcribed early after infection. Primer extension analysis indicates that transcription is initiated a short distance from the first ATG codon of open reading frame A240L. The deduced amino acid sequence of this open reading frame shows significant similarity with the human, yeast and vaccinia virus thymidylate kinases, the degree of identity being 23.7, 25 and 23.5%, respectively. The putative African swine fever virus thymidylate kinase sequence is essentially collinear with the other thymidylate kinase sequences, but contains a carboxy-terminal extension of 37 amino acids rich in glutamic and aspartic acids. The A240L protein conserves the ATP-binding and nucleotide/nucleoside-binding domains characteristic of thymidylate kinases.