Kiyoko Iwatsuki

Antigenic differences in the H proteins of canine distemper viruses

Antigenic properties between new Japanese field isolates and vaccine strains of canine distemper virus (CDV) have been compared using four monoclonal antibodies (MAbs) (JD-5, JD-7, JD-11 and d-7) against the hemagglutinin (H) proteins of CDV. JD-5, JD-7 and JD-11 are newly established antibodies. Three MAbs, namely d-7, JD-5 and JD-11, reacted similarly to all the CDV strains examined. However, JD-7 reacted much more strongly with the vaccine strains and an old field isolate than the recent field isolates in immunofluorescence, radio immunoprecipitation and virus neutralization assays. These results indicate that an antigenic region in the H protein, concerned with neutralization and recognized by JD-7, has been altered in the recent field isolates.

Immunohistochemical analysis of the lymphoid organs of dogs naturally infected with canine distemper virus

The pathogenesis of acute canine distemper in three naturally infected dogs was investigated. The lymphoid organs showed atrophy without secondary follicles. The distribution of canine distemper virus (CDV) antigens was examined immunohistochemically with monoclonal antibodies specific for canine Thy-1, immunoglobulin (Ig) M, CD4, CD8, CD21 and CD45RB, and anti-measles virus nucleocapsid protein serum. The viral antigens were located in the T-cell-dependent areas and in the follicles of lymphoid organs; they were observed mainly in the Thy-1, or CD4-positive cells, but also in the CD8-, CD21-, or IgM-positive cells. The results indicated that Thy-1-positive and CD4-positive T cells serve as major target cells for CDV during the acute stage of infection.

Properties of a new CDV isolate from a raccoon dog (Nyctereutes procyonoides viverrinus) in Japan

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Molecular Cloning and Sequence Analysis of the Phosphoprotein (P) Gene of the Lapinized Rinderpest Virus

We determined the nucleotide sequence of the coding region for the phosphoprotein (P) gene of the L strain of rinderpest virus (RPV). The gene encodes two overlapping open reading frames of 1521 and 531 nucleotides. Use of the first ATG would produce a P polypeptide of 507 amino acids, while use of the second ATG would produce a C polypeptide of 177 amino acids. In addition, the insertion of an extra G residue at the editing site generates an alternative mRNA potentially encoding the V protein of RPV. Homology comparisons of the P, C and V proteins among various viruses suggest that RPV is closer to measles virus (MV) than to canine distemper virus (CDV). Alignment of the sequences unique to the V protein revealed that the cysteine residues are well conserved among RPV, MV and CDV, and form a “zinc finger”-like motif.

Establishment of a persistent mutant of canine distemper virus

We produced a B95a lymphoid cell line persistently infected with canine distemper virus (CDV), in which virus-specific antigens were present in nearly 100% of cells without causing cytopathic effect. The virus recovered from this cell line was able to infect fresh B95a cells persistently, indicating that a persistent CDV was established.