title: The hemagglutinin-neuraminidase protein of Newcastle disease virus determines tropism and virulence.
abstract: The hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) plays a crucial role in the process of infection. However, the exact contribution of the HN gene to NDV pathogenesis is not known. In this study, the role of the HN gene in NDV virulence was examined. By use of reverse genetics procedures, the HN genes of a virulent recombinant NDV strain, rBeaudette C (rBC), and an avirulent recombinant NDV strain, rLaSota, were exchanged. The hemadsorption and neuraminidase activities of the chimeric viruses showed significant differences from those of their parental strains, but heterotypic F and HN pairs were equally effective in fusion promotion. The tissue tropism of the viruses was shown to be dependent on the origin of the HN protein. The chimeric virus with the HN protein derived from the virulent virus exhibited a tissue predilection similar to that of the virulent virus, and vice versa. The chimeric viruses with reciprocal HN proteins either gained or lost virulence, as determined by a standard intracerebral pathogenicity index test of chickens and by the mean death time in chicken embryos (a measure devised to classify these viruses), indicating that virulence is a function of the amino acid differences in the HN protein. These results are consistent with the hypothesis that the virulence of NDV is multigenic and that the cleavability of F protein alone does not determine the virulence of a strain.
authors.affiliation: Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Zhuhui
authors.initials: Z
authors.lastname: Huang
authors.forename: Aruna
authors.initials: A
authors.lastname: Panda
authors.forename: Subbiah
authors.initials: S
authors.lastname: Elankumaran
authors.forename: Dhanasekaran
authors.initials: D
authors.lastname: Govindarajan
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Rockemann
authors.forename: Siba K
authors.initials: SK
authors.lastname: Samal
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002642:Chick Embryo; D002678:Chimera / Q000235:genetics; D002522:Chlorocebus aethiops; D003588:Cytopathogenic Effect, Viral / Q000235:genetics / Q000502:physiology; D004279:DNA, Viral / Q000235:genetics; D005814:Genes, Viral; D015707:HN Protein / Q000235:genetics / Q000502:physiology*; D006801:Humans; D009154:Mutation; D009521:Newcastle Disease / Q000209:etiology; D009522:Newcastle disease virus / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*; D014709:Vero Cells; D014774:Virulence / Q000235:genetics / Q000502:physiology
chemical_list: D004279:DNA, Viral; D015707:HN Protein