title: Infectivity of influenza B virus in cultured human muscle.
abstract: Severe muscle symptoms, particularly in children, are frequently associated with influenza B virus infection. In this study we examined the effects of influenza B virus (Lee Strain) on cultured human muscle by light and electron microscopy (EM), immunofluorescence, hemadsorption and plaque assays. Muscle injury was also evaluated by the appearance of muscle-specific creatine kinase (CK) in the culture medium. By fluorescence immunocytochemistry viral antigen was demonstrated in muscle cell nuclei within 3 h postinoculation (p.i.) and in the cytoplasm at 6 h p.i. Membrane-associated viral antigen was seen at 16 h p.i., at which time budding influenza virus-like particles could be demonstrated by EM, both in myoblasts and multinucleated myotubes. At 16 h all cells were hemadsorption positive. Plaque assays showed peak virus production at 48 h (p.i.), at which time cytopathic effects (cell retraction, pycnosis and cytoplasmic vacuolization) were prominent and some cells detached from the substratum. Leakage of muscle-specific CK isozyme into the culture medium could be demonstrated as early as 6 h p.i. with peak enzyme activity around 40-48 h p.i. Cytopathic changes and virus production were observed both in myoblasts and myotubes indicating that both cell types are susceptible.
authors.forename: S
authors.initials: S
authors.lastname: Servidei
authors.forename: A F
authors.initials: AF
authors.lastname: Miranda
authors.forename: E T
authors.initials: ET
authors.lastname: Gamboa
mesh_terms: D003402:Creatine Kinase / Q000378:metabolism; D046508:Culture Techniques; D005455:Fluorescent Antibody Technique; D006387:Hemagglutination, Viral; D006801:Humans; D009981:Influenza B virus / Q000502:physiology*; D007251:Influenza, Human / Q000201:enzymology / Q000382:microbiology / Q000473:pathology; D009132:Muscles / Q000201:enzymology / Q000382:microbiology* / Q000473:pathology; D009220:Myositis / Q000209:etiology; D014779:Virus Replication
chemical_list: D003402:Creatine Kinase