Equine influenza viruses are a major cause of respiratory disease in horses worldwide and undergo antigenic drift. Several outbreaks of equine influenza occurred worldwide during 2010-2012, including in vaccinated animals, highlighting the importance of surveillance and virus characterisation. Virus isolates were characterised from more than 20 outbreaks over a 3-year period, including strains from the UK, Dubai, Germany and the USA. The haemagglutinin-1 (HA1) sequence of all isolates was determined and compared with OIE-recommended vaccine strains. Viruses from Florida clades 1 and 2 showed continued divergence from each other compared with 2009 isolates. The antigenic inter-relationships among viruses were determined using a haemagglutination-inhibition (HI) assay with ferret antisera and visualised using antigenic cartography. All European isolates belonged to Florida clade 2, all those from the USA belonged to Florida clade 1. Two subpopulations of clade 2 viruses were isolated, with either substitution A144V or I179V. Isolates from Dubai, obtained from horses shipped from Uruguay, belonged to Florida clade 1 and were similar to viruses isolated in the USA the previous year. The neuraminidase (NA) sequence of representative strains from 2007 and 2009 to 2012 was also determined and compared with that of earlier isolates dating back to 1963. Multiple changes were observed at the amino acid level and clear distinctions could be made between viruses belonging to Florida clade 1 and clade 2.
|Number of pages||15|
|State||Published - 2014|
Bibliographical noteFunding Information:
We would like to thank all members of the UK sentinel practice scheme for submission of samples and Toni-Ann Hammond and Stephanie Reedy for excellent technical support for EIV diagnostics. The surveillance programme and virus characterisation at the AHT were supported by funding from the Horserace Betting Levy Board (Equine Influenza Programme) and at the Gluck Equine Research Center by gifts in support of the OIE reference laboratory from Merck Animal Health, Zoetis Animal Health, ELANCO, and Hennessey Research Associates. We also thank the following in the USA who submitted PCR-positive samples to the OIE reference laboratory: Drs. Nicola Pusterla and Beate Crossley (University of California, Davis); Dr. Jennifer Morrow (Equine Diagnostic Solutions, Lexington, KY); Dr. Edward Dubovi (Cornell University, New York); Dr. Eileen Ostlund (USDA-APHIS, Iowa); Dr. Gail Scherba (University of Illinois at Urbana-Champaign); Dr. Hana van Campen (Colorado State University); and Dr. Stephen Sells (University of Kentucky).
- Antigenic cartography
- Equine influenza virus
ASJC Scopus subject areas
- Veterinary (all)