title: Effects of the HN gene C-terminal extensions on the Newcastle disease virus virulence.
abstract: The hemagglutinin-neuraminidase (HN) of Newcastle disease virus (NDV) is a multifunctional protein that has receptor recognition, neuraminidase, and fusion promotion activities. Sequence analysis revealed that the HN gene of many extremely low virulence NDV strains encodes a larger open-reading frame (616 amino acids, aa) with additional 45 aa at its C-terminus when compared with that (571 aa) of virulent NDV strains. Therefore, it has been suspected that the 45 aa extension at the C-terminus of the HN may affect the NDV virulence. In this study, we generated an NDV mesogenic strain Anhinga-based recombinant virus with an HN C-terminal extension of 45 aa (rAnh-HN-ex virus) using reverse genetics technology. The biological characterization of the recombinant virus showed that the rAnh-HN-ex virus had similar growth ability to its parental virus rAnh-wt both in embryonating chicken eggs and DF-1 cells. However, the pathogenicity of this recombinant virus in embryonating chicken eggs and day-old chickens decreased, as evidenced by a longer mean death time and lower intracerebral pathogenicity index when compared with the parental virus. This is consistent with our previous finding that the recombinant LaSota virus with a 45-aa extension at its HN C-terminal was attenuated in chickens and embryonating eggs. These results suggest that the HN protein C-terminal extension may contribute to the reduced virulence in some low virulence NDV strains.
authors.affiliation: Southeast Poultry Research Laboratory, Agricultural Research Services, United States Department of Agriculture, 934 College Station Road, Athens, GA, 30605, USA, zw830424@yahoo.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Zhang
authors.forename: Laszlo
authors.initials: L
authors.lastname: Zsak
authors.forename: Qingzhong
authors.initials: Q
authors.lastname: Yu
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002645:Chickens; D015707:HN Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009521:Newcastle Disease / Q000821:virology*; D009522:Newcastle disease virus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D016366:Open Reading Frames; D011201:Poultry Diseases / Q000821:virology*; D014774:Virulence
chemical_list: D015707:HN Protein
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