title: Virulence and in-vitro characteristics of four mutants of Newcastle disease virus.
mesh_terms: D000818:Animals; D002642:Chick Embryo; D006389:Hemagglutinins, Viral / Q000032:analysis; D006462:Hemolytic Plaque Technique; D007372:Interferons / Q000032:analysis; D009154:Mutation; D009439:Neuraminidase / Q000032:analysis; D009522:Newcastle disease virus; D013997:Time Factors; D014774:Virulence; D014776:Virus Cultivation; D014779:Virus Replication
chemical_list: D006389:Hemagglutinins, Viral; D007372:Interferons; D009439:Neuraminidase