title: Ultrastructural studies of influenza C. II. von Magnus phenomenon.
abstract: Influenza C was propagated by serial undiluted passage; conditions known to produce non-infectious (von Magnus) particles with influenza A and B. Following each passage infectious material was assayed for infectivity and haemagglutinating activity and the values related by calculating the log difference between infectivity and haemagglutinating titre (I:A ratio). Infectious material from each pass was examined for ultrastruct aberrations by negative strain electron microscopy. Influenza C exhibited a significantly smaller decrease in I:A ratio than exhibiyed by similarly propagated influenza A and B. Ultrastructural examination of the serially passed influenza C revealed no production of morphologically aberrant forms, whereas serially passed influenza B produced a strikingly altered morphology.
mesh_terms: D000818:Animals; D002642:Chick Embryo; D006389:Hemagglutinins, Viral / Q000032:analysis; D009980:Influenza A virus / Q000276:immunology / Q000472:pathogenicity; D009522:Newcastle disease virus / Q000276:immunology / Q000472:pathogenicity; D009975:Orthomyxoviridae / Q000276:immunology / Q000472:pathogenicity / Q000648:ultrastructure*; D014776:Virus Cultivation
chemical_list: D006389:Hemagglutinins, Viral