title: Potentially virulent Newcastle disease viruses are maintained in migratory waterfowl populations.
abstract: Forty-seven Newcastle disease virus (NDV) strains isolated from fecal samples of waterfowls in Alaska and Siberia from 1991 to 1996 were analyzed for their virulence. None of the viruses formed plaques on MDBK cells in the absence of trypsin. Of these, 29 strains showed virulent character by the mean death time with the minimum lethal dose in chicken embryos comparable to velogenic NDV strains. Of the 29 strains, 11 were sequenced for their fusion protein (F) gene. The results showed that 5 of them contained a pair of dibasic amino acids at the cleavage site of the F, which is of a virulent type. The present results suggest that potentially virulent strains of NDV are maintained in migratory waterfowl populations in nature, and that some of those may be transmitted to domestic poultry and acquire pathogenicity during passages in chicken population.
authors.affiliation: Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Takakuwa
authors.forename: T
authors.initials: T
authors.lastname: Ito
authors.forename: A
authors.initials: A
authors.lastname: Takada
authors.forename: K
authors.initials: K
authors.lastname: Okazaki
authors.forename: H
authors.initials: H
authors.lastname: Kida
mesh_terms: D000413:Alaska / Q000453:epidemiology; D000595:Amino Acid Sequence; D000818:Animals; D000835:Animals, Wild / Q000821:virology*; D001483:Base Sequence; D001717:Birds / Q000821:virology*; D002642:Chick Embryo; D004196:Disease Outbreaks / Q000662:veterinary; D004372:Ducks / Q000821:virology; D005243:Feces / Q000821:virology*; D005777:Geese / Q000821:virology; D009521:Newcastle Disease / Q000453:epidemiology / Q000821:virology*; D009522:Newcastle disease virus / Q000145:classification / Q000302:isolation & purification / Q000472:pathogenicity*; D010802:Phylogeny; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics; D012800:Siberia / Q000453:epidemiology; D014774:Virulence
chemical_list: D012367:RNA, Viral