Genotyping of Newcastle disease viruses isolated from 2001 to 2007 in Japan

Seventeen isolates of Newcastle disease virus (NDV) were obtained from various prefectures in Japan during the years 2001-2007 and were genotypically analyzed by the reverse transcriptase-polymerase chain reaction (RT-PCR) method coupled with direct sequencing. These NDV isolates were classified into three genetic groups that had been reported previously, namely, genotypes I, VI and VII. The isolate from an aigamo duck was classified into genotype I with isolates mainly from waterfowl. All isolates from pigeons were classified into genotype VI, the predominant genotype responsible for most Newcastle disease outbreaks in pigeons. The isolate from a pet bird was classified into genotype VI, distinct from the remaining viruses in genotype VI. All isolates from chickens were classified into genotype VII, the predominant genotype responsible for most Newcastle disease outbreaks in the East Asian countries. Among the isolates from chickens, isolates after 2002 were genetically most closely related with isolates in Korea. The single isolate from a wild cormorant was also classified into genotype VII, although it was different from the recent NDV epidemic strain in Japan.