title: Influenza virus infection in multinucleated skeletal myofibers.
abstract: We examined the progression of the WSN influenza virus infection in isolated, multinucleated rat skeletal myofibers. Contrary to mononucleated cells, the adsorbed virions showed markedly delayed entry kinetics. Viral budding occurred on the sarcolemma, but the hemagglutinin envelope glycoprotein matured inefficiently and was poorly cleaved. Compatible with this, plaque assays indicated that infective viral particles were not formed. In situ hybridization studies showed that at low-dose infection, viral RNA production was restricted to one or a few nuclei within a myofiber. Dual in situ hybridization indicated that two different viral RNAs usually co-localized in the same nucleus or nuclei, suggesting that different viral genome segments replicated in the same nucleus. Newly synthesized viral ribonucleoprotein particles (vRNPs) did not re-enter virgin nuclei. Therefore, a single infected nucleus was able to support viral protein production, and notably, these proteins could reach hundreds of micrometers from the nucleus of origin. These results suggest that after viral disassembly in the endosome, the genome segments remained glued together and entered a myonucleus as a package. Spreading of the infection into virgin nuclei either by vRNPs or newly made virions did not occur, and thus the infection was abortive.
authors.affiliation: Institute of Biomedicine, Department of Anatomy and Cell Biology, PO Box 5000, FIN-90014 University of Oulu, Finland.
authors.forename: Mika
authors.initials: M
authors.lastname: Nevalainen
authors.forename: Marja
authors.initials: M
authors.lastname: Nissinen
authors.forename: Mika
authors.initials: M
authors.lastname: Kaakinen
authors.forename: Kalervo
authors.initials: K
authors.lastname: Metsikkö
mesh_terms: D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000821:virology; D005260:Female; D017403:In Situ Hybridization; D066298:In Vitro Techniques; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D018485:Muscle Fibers, Skeletal / Q000648:ultrastructure / Q000821:virology*; D009975:Orthomyxoviridae / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology / Q000648:ultrastructure; D009976:Orthomyxoviridae Infections / Q000473:pathology / Q000821:virology*; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D051381:Rats; D012508:Sarcolemma / Q000648:ultrastructure / Q000821:virology; D014764:Viral Proteins / Q000378:metabolism; D053586:Virus Internalization; D057074:Virus Release
chemical_list: D012367:RNA, Viral; D014764:Viral Proteins