Antibody Responses to a Reverse Genetics-Derived Bivalent Inactivated Equine Influenza Vaccine in Thoroughbred Horses

Minoru Ohta; Hiroshi Bannai; Yoshinori Kambayashi; Koji Tsujimura; Norihisa Tamura; Yohei Iwamoto; Ai Wakuno; Seiya Yamayoshi; Yoshihiro Kawaoka; Manabu Nemoto

doi:10.1016/j.jevs.2021.103860

Antibody Responses to a Reverse Genetics-Derived Bivalent Inactivated Equine Influenza Vaccine in Thoroughbred Horses

J Equine Vet Sci. 2022 Feb:109:103860. doi: 10.1016/j.jevs.2021.103860. Epub 2021 Dec 29.

Authors

Affiliations

¹ Equine Research Institute, Japan Racing Association, Tochigi, Japan.
² Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan.
³ The Horse Racing School, Japan Racing Association, Chiba, Japan.
⁴ Division of Virology, Institute of Medical Science, University of Tokyo, Tokyo, Japan; The Research Center for Global Viral Diseases, National Center for Global Health and Medicine Research Institute, Tokyo, Japan.
⁵ Division of Virology, Institute of Medical Science, University of Tokyo, Tokyo, Japan; The Research Center for Global Viral Diseases, National Center for Global Health and Medicine Research Institute, Tokyo, Japan; Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI.
⁶ Equine Research Institute, Japan Racing Association, Tochigi, Japan. Electronic address: nemoto_manabu@equinst.go.jp.

PMID: 34973368
DOI: 10.1016/j.jevs.2021.103860

Abstract

Updating vaccine strains is important to control equine influenza (EI). Previously, we reported that a monovalent inactivated EI vaccine derived from a virus generated by reverse genetics (RG) elicited immunogenicity in horses. In the present study, we compared antibody responses to a bivalent inactivated EI vaccine generated by RG and a commercially available bivalent inactivated EI (CO) vaccine derived from wild-type equine influenza viruses in Thoroughbred horses. The CO vaccine contained A/equine/Ibaraki/1/2007 (Florida sub-lineage clade 1) and A/equine/Yokohama/aq13/2010 (Florida sub-lineage clade 2) as vaccine strains. We generated two RG viruses possessing the hemagglutinin and neuraminidase genes from A/equine/Ibaraki/1/2007 or A/equine/Yokohama/aq13/2010. These viruses were inactivated by formalin, and the hemagglutinin titer of the RG vaccine was adjusted to be the same as that of the CO vaccine. Sixteen unvaccinated yearlings (7 for the RG vaccine group and 9 for the CO vaccine group) received two doses of a primary vaccination course four weeks apart. Thirty-two vaccinated adult horses (18 in the RG-vaccinated group and 14 in the CO vaccine group) received a single dose of a booster vaccination. The patterns of hemagglutination inhibition antibody response to the primary and booster vaccinations were similar for the RG and CO groups in unvaccinated yearlings and vaccinated adult horses. These results suggest that a bivalent vaccine derived from RG viruses elicits equivalent immunogenicity to that elicited by a CO vaccine derived from wild-type viruses. RG viruses can, therefore, be used in multivalent as well as monovalent vaccines for horses.

Keywords: Antibody response; Equine influenza; Inactivated vaccine; Reverse genetics.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Antibodies, Viral
Antibody Formation
Horse Diseases* / prevention & control
Horses
Influenza A virus*
Influenza Vaccines*
Reverse Genetics / veterinary

Substances

Antibodies, Viral
Influenza Vaccines