Cellular proteins in influenza virus particles.

Department of Microbiology, Mount Sinai School of Medicine, New York, New York, United States of America.
PLoS Pathogens (Impact Factor: 8.14). 07/2008; 4(6):e1000085. DOI: 10.1371/journal.ppat.1000085
Source: PubMed

ABSTRACT Virions are thought to contain all the essential proteins that govern virus egress from the host cell and initiation of replication in the target cell. It has been known for some time that influenza virions contain nine viral proteins; however, analyses of other enveloped viruses have revealed that proteins from the host cell can also be detected in virions. To address whether the same is true for influenza virus, we used two complementary mass spectrometry approaches to perform a comprehensive proteomic analysis of purified influenza virus particles. In addition to the aforementioned nine virus-encoded proteins, we detected the presence of 36 host-encoded proteins. These include both cytoplasmic and membrane-bound proteins that can be grouped into several functional categories, such as cytoskeletal proteins, annexins, glycolytic enzymes, and tetraspanins. Interestingly, a significant number of these have also been reported to be present in virions of other virus families. Protease treatment of virions combined with immunoblot analysis was used to verify the presence of the cellular protein and also to determine whether it is located in the core of the influenza virus particle. Immunogold labeling confirmed the presence of membrane-bound host proteins on the influenza virus envelope. The identification of cellular constituents of influenza virions has important implications for understanding the interactions of influenza virus with its host and brings us a step closer to defining the cellular requirements for influenza virus replication. While not all of the host proteins are necessarily incorporated specifically, those that are and are found to have an essential role represent novel targets for antiviral drugs and for attenuation of viruses for vaccine purposes.

1 Bookmark
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The ability of antibodies binding the influenza hemagglutinin protein to neutralize viral infectivity is of key importance in the design of next-generation vaccines and for prophylactic and therapeutic use. The two antibodies CR6261 and CR8020 have recently been shown to efficiently neutralize influenza A infection by binding to and inhibiting the influenza A hemagglutinin (HA) protein that is responsible for membrane fusion in the early steps of viral infection. Here, we use single-particle fluorescence microscopy to correlate the number of antibodies or Fab fragments bound to an individual virion with the capacity of the same virus particle to undergo membrane fusion. To this end, individual, infectious virus particles bound by fluorescently-labeled antibodies/Fab are visualized as they fuse to a planar, supported lipid bilayer. The fluorescence intensity arising from the virus-bound antibodies/Fab is used to determine the number of molecules attached to viral HA, while a fluorescent marker in the viral membrane is used to simultaneously obtain kinetic information on the fusion process. We experimentally determine that the stoichiometry required for fusion inhibition by both antibody and Fab leaves large numbers of unbound HA epitopes on the viral surface. Kinetic measurements of the fusion process reveal that those few particles capable of fusion at high antibody/Fab coverage display significantly slower hemifusion kinetics. Overall, our results support a membrane fusion mechanism requiring the stochastic, coordinated action of multiple HA trimers and a model of fusion inhibition by stem-binding antibodies through disruption of this coordinated action.
    Proceedings of the National Academy of Sciences 10/2014; 111(48):E5143–E5148. · 9.81 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Great efforts have been made to develop robust signal-generating fluorescence materials which will help in improving the rapid diagnostic test (RDT) in terms of sensitivity and quantification. In this study, we developed coumarin-derived dendrimer-based fluorescent immunochromatographic strip test (FICT) assay with enhanced sensitivity as a quantitative diagnostic tool in typical RDT environments. The accuracy of the proposed FICT was compared with that of dot blot immunoassay techniques and conventional RDTs. Through conjugation of coumarin-derived dendrimers with latex beads, fluorescent emission covering broad output spectral ranges was obtained which provided a distinct advantage of easy discrimination of the fluorescent emission of the latex beads with a simple insertion of a long-pass optical filter away from the excitation wavelength. The newly developed FICT assay was able to detect 100 ng/10 μL of influenza A nucleoprotein (NP) antigen within 5 minutes, which corresponded to 2.5-fold higher sensitivity than that of the dot blot immunoassay or conventional RDTs. Moreover, the FICT assay was confirmed to detect at least four avian influenza A subtypes (H5N3, H7N1, H7N7, and H9N2). On applying the FICT to the clinical swab samples infected with respiratory viruses, our FICT assay was confirmed to differentiate influenza H1N1 infection from other respiratory viral diseases. These data demonstrate that the proposed FICT assay is able to detect zoonotic influenza A viruses with a high sensitivity, and it enables the quantitation of the infection intensity by providing the numerical diagnostic values; thus demonstrating enhanced detectability of influenza A viruses.
    Theranostics 01/2014; 4(12):1239-49. · 7.81 Impact Factor
  • Source

Full-text (3 Sources)

Available from
May 30, 2014

Similar Publications