Identification and nucleotide sequence of the thymidine kinase gene of swinepox virus

Using degenerative oligonucleotide probes, representing two different conserved regions of poxvirus and mammalian thymidine kinase (TK) genes, the swinepox virus (SPV) TK gene was mapped to a 1.7-kb BamHI-HindIII fragment of the viral genome. Nucleotide sequencing of this DNA piece revealed that the SPV TK gene was encoded by an open reading frame (ORF) of 177 codons. Immediately downstream of the TK gene was a second ORF with homologues at the same location in both capripoxvirus and leporipoxvirus genomes. A similar gene had translocated to near the left hand terminus of the vaccinia virus (orthopoxvirus) genome. Flanking the two SPV genes were ORFs whose counterparts in other poxvirus genera are located at the same relative positions. SPV appeared to be most closely related to capripoxvirus, based on the organization of the four genes and on the percentage of identical amino acid residues of the respective encoded proteins.