This paper presents the entire nucleotide sequence of the thymidine Ki
nase (TK) gene of canine herpesvirus (CHV). The gene was located withi
n a 2.1 kbp EcoRV fragment by Southern-blot hybridization with a probe
derived from the known feline herpesvirus type 1 (FHV-1) TK gene. An
open reading frame (ORF) of 987 nucleotides, capable of encoding a TK
translation product of 328 amino acids, was identified. Alignment of t
he predicted amino acid sequence of the CHV TK with other herpesvirus
TKs revealed homologies of 25-47%. The proposed nucleotide-binding sit
e and thymidine-binding site sequences of known herpesvirus TKs could
be aligned with similar sequences in CHV TK. Northern-blot analysis re
vealed 1.3 kb and 5.0 kb mRNAs as the TK-specific transcripts. It is p
robable that the 1.3 kb transcript codes for the CHV TK and that the 5
.0 kb transcript codes for the CHV TK and the downstream sequence.