Molecular analysis of the nucleocapsid protein of recent isolates of canine distemper virus in Japan.

We analyzed the molecular properties of the nucleocapsid protein (NP) of canine distemper viruses (CDV), isolated between 1992 and 1995 in Japan. Four CDV field isolates (Yanaka, Ueno, Hamamatsu, and Adachi strains) obtained were antigenically identical. Sequence analysis of entire region of the NP gene of a field isolate, the Yanaka strain, revealed that the NP gene contained 1683 nucleotides and was 93.2% homologous with a laboratory strain, the Onderstepoort strain. The deduced amino acid sequence contained 523 amino acids and was 95.2 and 99% homologous with those of the Onderstepoort and a virulent strain, A75/17 strain, respectively. Since most of the diversities in amino acid sequence occurred in two domains, at the N'- and the C'- termini, we further sequenced 3'-terminal regions of the remaining three field isolates. Based on the sequences, the new CDV isolates had one cluster that distinguished them from the laboratory strain.