SEQUENCES OF THE RIBONUCLEOTIDE REDUCTASE-ENCODING GENES OF EQUINE HERPESVIRUS-4

The equine herpesvirus 4 (EHV-4) genes encoding the two subunits of th e enzyme ribonucleotide reductase (RR) were cloned and their nucleotid e (nt) sequences determined. The large subunit (RR1) is predicted to c omprise 789 amino acids (aa), which compares with lengths of 790, 775 and 1137 aa for the RR1 proteins encoded by equine herpesvirus 1 (EHV- 1) gene 21, varicella tester virus (VZV) gene 19 and herpes simplex vi rus type 1 (HSV-1) UL39, respectively. In common with VZV RR1, the EHV -4 RR1 protein lacks the N-terminal domain of HSV-1 RR1 which possesse s protein kinase activity. EHV-4 RR1 demonstrates identities of 88, 52 and 29% with the RR1 proteins of EHV-1, VZV and HSV-1, respectively. The small subunit (RR2) is predicted to be 320 aa in length, which com pares with lengths of 321, 306 and 340 aa for the RR2 proteins encoded by EHV-1 gene 20, VZV gene 18 and HSV-1 UL40, respectively. The EHV-4 RR2 protein exhibits identities of 90, 60 and 55% with the RR2 protei ns of EHV-1, VZV and HSV-1, respectively.