Vaccination remains the most effective approach for preventing and controlling equine influenza virus (EIV) in horses. However, the ongoing evolution of EIV has increased the genetic and antigenic differences between currently available vaccines and circulating strains, resulting in suboptimal vaccine efficacy. As recommended by the World Organization for Animal Health (OIE), the inclusion of representative strains from clade 1 and clade 2 Florida sublineages of EIV in vaccines may maximize the protection against presently circulating viral strains. In this study, we used reverse genetics technologies to generate a bivalent EIV live-attenuated influenza vaccine (LAIV). We combined our previously described clade 1 EIV LAIV A/equine/Ohio/2003 H3N8 (Ohio/03 LAIV) with a newly generated clade 2 EIV LAIV that contains the six internal genes of Ohio/03 LAIV and the HA and NA of A/equine/Richmond/1/2007 H3N8 (Rich/07 LAIV). The safety profile, immunogenicity, and protection efficacy of this bivalent EIV LAIV was tested in the natural host, horses. Vaccination of horses with the bivalent EIV LAIV, following a prime-boost regimen, was safe and able to confer protection against challenge with clade 1 (A/equine/Kentucky/2014 H3N8) and clade 2 (A/equine/Richmond/2007) wild-type (WT) EIVs, as evidenced by a reduction of clinical signs, fever, and virus excretion. This is the first description of a bivalent LAIV for the prevention of EIV in horses that follows OIE recommendations. In addition, since our bivalent EIV LAIV is based on the use of reverse genetics approaches, our results demonstrate the feasibility of using the backbone of clade 1 Ohio/03 LAIV as a master donor virus (MDV) for the production and rapid update of LAIVs for the control and protection against other EIV strains of epidemiological relevance to horses.
|State||Published - Oct 11 2019|
Bibliographical noteFunding Information:
Funding: This research was partially funded by the University of Rochester Technology Development Funding to L.M.-S. and T.M.C., P.R.M. was funded by the Medical Research Council of the United Kingdom (Grant MC_UU_120/14/9). T.M.C. and S.R. were supported by the Kentucky Agricultural Experiment Station (Project no. KY014053) and by a pilot study funding from the College of Agriculture, Food, and the Environment at University of Kentucky. F.S.O. was supported by a Young Investigator Award from the American Quarter Horse Foundation, and by the Geoffrey C. Hughes Foundation.
© 2019 by the authors. Licensee MDPI, Basel, Switzerland.
- Equine influenza virus
- Live-attenuated influenza vaccine
- Master donor virus
- Recombinant virus
- Reverse genetics techniques
ASJC Scopus subject areas
- Infectious Diseases