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Proc Natl Acad Sci USA. Pathogenesis and transmission of swine origin A(H3N2)v influenza viruses in ferrets

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  • Proc Natl Acad Sci USA. Pathogenesis and transmission of swine origin A(H3N2)v influenza viruses in ferrets

    [Source: Proc Natl Acad Sci USA, full text: (LINK). Abstract, edited.]
    Pathogenesis and transmission of swine origin A(H3N2)v influenza viruses in ferrets


    Melissa B. Pearce, Akila Jayaraman, Claudia Pappas, Jessica A. Belser, Hui Zeng, Kortney M. Gustin, Taronna R. Maines, Xiangjie Sun, Rahul Raman, Nancy J. Cox, Ram Sasisekharan, Jaqueline M. Katz, and Terrence M. Tumpey

    Author Affiliations: <SUP>a</SUP>Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA 30333; and <SUP>b</SUP>Harvard?MIT Division of Health Sciences and Technology, Singapore?MIT Alliance for Research and Technology, Department of Biological Engineering, Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139
    Edited by Peter Palese, Mount Sinai School of Medicine, New York, NY, and approved January 18, 2012 (received for review December 5, 2011)



    Abstract

    Recent isolation of a novel swine-origin influenza A H3N2 variant virus [A(H3N2)v] from humans in the United States has raised concern over the pandemic potential of these viruses. Here, we analyzed the virulence, transmissibility, and receptor-binding preference of four A(H3N2)v influenza viruses isolated from humans in 2009, 2010, and 2011. High titers of infectious virus were detected in nasal turbinates and nasal wash samples of A(H3N2)v-inoculated ferrets. All four A(H3N2)v viruses possessed the capacity to spread efficiently between cohoused ferrets, and the 2010 and 2011 A(H3N2)v isolates transmitted efficiently to na?ve ferrets by respiratory droplets. A dose-dependent glycan array analysis of A(H3N2)v showed a predominant binding to α2-6?sialylated glycans, similar to human-adapted influenza A viruses. We further tested the viral replication efficiency of A(H3N2)v viruses in a relevant cell line, Calu-3, derived from human bronchial epithelium. The A(H3N2)v viruses replicated in Calu-3 cells to significantly higher titers compared with five common seasonal H3N2 influenza viruses. These findings suggest that A(H3N2)v viruses have the capacity for efficient replication and transmission in mammals and underscore the need for continued public health surveillance.


    Footnotes

    <SUP>1</SUP>To whom correspondence should be addressed. E-mail: tft9@cdc.gov.

    Author contributions: M.B.P., C.P., H.Z., T.R.M., R.R., N.J.C., R.S., J.M.K., and T.M.T. designed research; M.B.P., A.J., C.P., J.A.B., H.Z., K.M.G., T.R.M., X.S., and T.M.T. performed research; A.J., H.Z., R.R., and R.S. contributed new reagents/analytic tools; M.B.P., A.J., C.P., J.A.B., H.Z., K.M.G., T.R.M., X.S., R.R., N.J.C., R.S., J.M.K., and T.M.T. analyzed data; and M.B.P., C.P., J.A.B., T.R.M., R.R., N.J.C., R.S., J.M.K., and T.M.T. wrote the paper.

    The authors declare no conflict of interest.

    This article is a PNAS Direct Submission.

    This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1119945109/-/DCSupplemental.
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  • #2
    Re: Proc Natl Acad Sci USA. Pathogenesis and transmission of swine origin A(H3N2)v influenza viruses in ferrets

    Novel Swine Influenza Virus Has 'Pandemic Potential'

    February 27, 2012 ? A novel strain of a swine influenza virus that sickened just 12 individuals in 2011 nevertheless merits continued surveillance because tests indicate that the emerging virus has "pandemic potential" among humans, according to an article published online February 21 in the Proceedings of the National Academy of Sciences.

    In the tests, ferrets were inoculated with isolates of this novel virus, as well as earlier versions. The viruses efficiently replicated and spread among the ferrets, which resemble humans in terms of lung physiology and susceptibility to influenza viruses, lead author Melissa Pearce, PhD, an associate service fellow at the US Centers for Disease Control and Prevention (CDC), and coauthors write.

    The swine influenza virus from 2011 is designated A(H3N2)v, with the "v" standing for variant. What accounts for the variance in this particular virus is a gene from the pandemic 2009 influenza A(H1N1) virus that codes for matrix proteins in the viral shell.

    Seasonal human influenza strains now in circulation include an A(H3N2) virus, as well as the pandemic 2009 A(H1N1) virus. The current trivalent influenza vaccine guards against both of these viruses in addition to an influenza B strain. However, Dr. Pearce and colleagues write that the swine influenza variant is antigenetically distinct from the current human A(H3N2) virus, and therefore "would not be well covered by the current trivalent vaccine."

    With that limitation in mind, the CDC has already embarked on developing a vaccine for the A(H3N2)v virus from 2011 in case it should begin to spread among humans on a sustained basis.

    ..

    Although the CDC has identified only 12 cases of a swine influenza virus with a gene borrowed from the 2009 pandemic version, a new study says it has the ability to replicate and spread efficiently.

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