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J Virol. The intra- and inter-host evolutionary dynamics of equine influenza virus.

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  • J Virol. The intra- and inter-host evolutionary dynamics of equine influenza virus.

    [Source: US National Library of Medicine (LINK). Edited.]

    J Virol. 2010 May 5. [Epub ahead of print]

    The intra- and inter-host evolutionary dynamics of equine influenza virus.

    Murcia PR, Baillie GJ, Daly J, Elton D, Jervis C, Mumford JA, Newton R, Parrish CR, Hoelzer K, Dougan G, Parkhill J, Lennard N, Ormond D, Moule S, Whitwham A, McCauley JW, McKinley TJ, Holmes EC, Grenfell BT, Wood JL. - Cambridge Infectious Diseases Consortium, Department of Veterinary Medicine, University of Cambridge, United Kingdom; Wellcome Trust Sanger Institute. Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom; Animal Health Trust, Centre for Preventive Medicine, Lanwades Park, Newmarket, United Kingdom; Baker Institute of Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, USA; Division of Virology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom; Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, Pennsylvania, USA; Fogarty International Center, National Institutes of Health, Bethesda, USA.

    Determining the evolutionary basis of cross-species transmission and immune evasion is key to understanding the mechanisms that control the emergence of either new viruses or novel antigenic variants with pandemic potential. The hemagglutinin glycoprotein of influenza A viruses is a critical host range determinant and a major target of neutralizing antibodies. Equine influenza virus is a significant pathogen of the horse that causes periodical outbreaks of disease even in populations with high vaccination coverage. EIV has also jumped the species barrier and emerged as a novel respiratory pathogen in dogs - canine influenza virus. We studied the dynamics of equine influenza virus evolution in horses at the intra-host level, and how this evolutionary process is affected by inter-host transmission in a natural setting. To this end, we performed clonal sequencing of the hemagglutinin 1 gene derived from individual animals at different times post-infection. Our results show that despite the population consensus sequence remaining invariant, genetically distinct subpopulations persist during the course of infection and are also transmitted, with some variants likely to change antigenicity. We also detected a natural case of mixed infection in an animal infected during an outbreak of equine influenza, raising the possibility of reassortment between different strains of virus. In sum, our data suggest that transmission bottlenecks may not be as narrow as originally perceived and that the genetic diversity required to adapt to new host species may be partially present in the donor host and potentially transmitted to the recipient host.

    PMID: 20444896 [PubMed - as supplied by publisher]