Molecular epidemiology of Newcastle disease in Republic of Korea.

Twenty-three strains of Newcastle disease virus (NDV) isolated between 1988 and 1999 in Republic of Korea were studied by partial nucleotide sequencing of fusion (F) gene and phylogenetic analysis. Most of Korean strains formed a distinctive cluster in genotype VI and they were genetically distant (4.0-8.7%) from other subtypes (a, b, c, d, and e), and termed provisionally VIf. Some Korean strains isolated in 1995 were grouped into genotype VIIa and they were closer to Taiwan strains than western Europe. The results suggest that the genotype VIf strains have been maintained by enzootic infections during the past decade, while genotype VIIa appears to be introduced more recently in Republic of Korea.