Tyrosines in the influenza A virus M2 protein cytoplasmic tail are critical for production of infectious virus particles.

W Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins University, Bloomberg School of Public Health, 615 North Wolfe Street, Suite 5132, Baltimore, Maryland 21205, USA.
Journal of Virology (Impact Factor: 4.65). 09/2010; 84(17):8765-76. DOI: 10.1128/JVI.00853-10
Source: PubMed

ABSTRACT The cytoplasmic tail of the influenza A virus M2 protein is required for the production of infectious virions. In this study, critical residues in the M2 cytoplasmic tail were identified by single-alanine scanning mutagenesis. The tyrosine residue at position 76, which is conserved in >99% of influenza virus strains sequenced to date, was identified as being critical for the formation of infectious virus particles using both reverse genetics and a protein trans-complementation assay. Recombinant viruses encoding M2 with the Y76A mutation demonstrated replication defects in MDCK cells as well as in primary differentiated airway epithelial cell cultures, defects in the formation of filamentous virus particles, and reduced packaging of nucleoprotein into virus particles. These defects could all be overcome by a mutation of serine to tyrosine at position 71 of the M2 cytoplasmic tail, which emerged after blind passage of viruses containing the Y76A mutation. These data confirm and extend our understanding of the significance of the M2 protein for infectious virus particle assembly.

Download full-text


Available from: Andrew Pekosz, Jul 07, 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Influenza A virus causes seasonal epidemics, sporadic pandemics and is a significant global health burden. Influenza virus is an enveloped virus that contains a segmented negative strand RNA genome. Assembly and budding of progeny influenza virions is a complex, multi-step process that occurs in lipid raft domains on the apical membrane of infected cells. The viral proteins hemagglutinin (HA) and neuraminidase (NA) are targeted to lipid rafts, causing the coalescence and enlargement of the raft domains. This clustering of HA and NA may cause a deformation of the membrane and the initiation of the virus budding event. M1 is then thought to bind to the cytoplasmic tails of HA and NA where it can then polymerize and form the interior structure of the emerging virion. M1, bound to the cytoplasmic tails of HA and NA, additionally serves as a docking site for the recruitment of the viral RNPs and may mediate the recruitment of M2 to the site of virus budding. M2 initially stabilizes the site of budding, possibly enabling the polymerization of the matrix protein and the formation of filamentous virions. Subsequently, M2 is able to alter membrane curvature at the neck of the budding virus, causing membrane scission and the release of the progeny virion. This review investigates the latest research on influenza virus budding in an attempt to provide a step-by-step analysis of the assembly and budding processes for influenza viruses.
    Virology 03/2011; 411(2):229-36. DOI:10.1016/j.virol.2010.12.003 · 3.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Current influenza vaccines based on the hemagglutinin protein are strain specific and do not provide good protection against drifted viruses or emergence of new pandemic strains. An influenza vaccine that can confer cross-protection against antigenically different influenza A strains is highly desirable for improving public health. To develop a cross protective vaccine, we generated influenza virus-like particles containing the highly conserved M2 protein in a membrane-anchored form (M2 VLPs), and investigated their immunogenicity and breadth of cross protection. Immunization of mice with M2 VLPs induced anti-M2 antibodies binding to virions of various strains, M2 specific T cell responses, and conferred long-lasting cross protection against heterologous and heterosubtypic influenza viruses. M2 immune sera were found to play an important role in providing cross protection against heterosubtypic virus and an antigenically distinct 2009 pandemic H1N1 virus, and depletion of dendritic and macrophage cells abolished this cross protection, providing new insight into cross-protective immune mechanisms. These results suggest that presenting M2 on VLPs in a membrane-anchored form is a promising approach for developing broadly cross protective influenza vaccines.
    PLoS ONE 01/2011; 6(1):e14538. DOI:10.1371/journal.pone.0014538 · 3.53 Impact Factor