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Ohta M, Kambayashi Y, Mita H, Kuroda T, Bannai H, Tsujimura K, Yamanaka T, Garvey M, Cullinane A, Yamayoshi S, Kawaoka Y, Nemoto M. Protective efficacy of a reverse genetics-derived inactivated vaccine against equine influenza virus in horses. Vaccine 2022; 40:6362-6366. [PMID: 36175213 DOI: 10.1016/j.vaccine.2022.09.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/09/2022] [Accepted: 09/15/2022] [Indexed: 01/27/2023]
Abstract
Updating vaccine strains is essential to control equine influenza. We evaluated the protective efficacy of an inactivated equine influenza vaccine derived from viruses generated by reverse genetics (RG) in horses in an experimental viral challenge study. Wild-type (WT) virus (A/equine/Tipperary/1/2019) and virus generated by RG (consisting of hemagglutinin and neuraminidase genes from A/equine/Tipperary/1/2019 and six other genes from high-growth A/Puerto Rico/8/34) were inactivated by formalin for vaccine use. Twelve 1-year-old naïve horses with no antibodies against equine influenza virus were assigned to three groups (each n = 4): control, WT, and RG. They were vaccinated twice, 4 weeks apart, and were challenged with A/equine/Tipperary/1/2019 2 weeks after the second vaccination. All four horses in the control group and one horse in the WT group had pyrexia for multiple days and respiratory illness, and one horse in the RG group had pyrexia for 2 days without respiratory illness. The mean rectal temperatures and the mean concentrations of serum amyloid A in the WT and RG groups were significantly lower than those in the control group, with no significant differences between them. The WT and RG vaccines significantly reduced viral shedding relative to the control. The protective efficacy of the RG-derived inactivated vaccine against equine influenza virus is comparable to that of the vaccine derived from WT viruses in horses. The RG technique can make it easy to update equine influenza vaccine strains.
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Affiliation(s)
- Minoru Ohta
- Equine Research Institute, Japan Racing Association, Tochigi, Japan
| | | | - Hiroshi Mita
- Equine Research Institute, Japan Racing Association, Tochigi, Japan
| | - Taisuke Kuroda
- Equine Research Institute, Japan Racing Association, Tochigi, Japan
| | - Hiroshi Bannai
- Equine Research Institute, Japan Racing Association, Tochigi, Japan
| | - Koji Tsujimura
- Equine Research Institute, Japan Racing Association, Tochigi, Japan
| | - Takashi Yamanaka
- Equine Research Institute, Japan Racing Association, Tochigi, Japan
| | - Marie Garvey
- Virology Unit, Irish Equine Centre, Kildare, Ireland
| | - Ann Cullinane
- Virology Unit, Irish Equine Centre, Kildare, Ireland
| | - Seiya Yamayoshi
- 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
| | - Yoshihiro Kawaoka
- 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, USA
| | - Manabu Nemoto
- Equine Research Institute, Japan Racing Association, Tochigi, Japan.
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Ohta M, Bannai H, Kambayashi Y, Tsujimura K, Tamura N, Iwamoto Y, Wakuno A, Yamayoshi S, Kawaoka Y, Nemoto M. Antibody Responses to a Reverse Genetics-Derived Bivalent Inactivated Equine Influenza Vaccine in Thoroughbred Horses. J Equine Vet Sci 2021; 109:103860. [PMID: 34973368 DOI: 10.1016/j.jevs.2021.103860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/20/2021] [Accepted: 12/24/2021] [Indexed: 11/27/2022]
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.
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Affiliation(s)
- Minoru Ohta
- Equine Research Institute, Japan Racing Association, Tochigi, Japan
| | - Hiroshi Bannai
- Equine Research Institute, Japan Racing Association, Tochigi, Japan
| | | | - Koji Tsujimura
- Equine Research Institute, Japan Racing Association, Tochigi, Japan
| | - Norihisa Tamura
- Equine Research Institute, Japan Racing Association, Tochigi, Japan
| | - Yohei Iwamoto
- Hidaka Training and Research Center, Japan Racing Association, Hokkaido, Japan
| | - Ai Wakuno
- The Horse Racing School, Japan Racing Association, Chiba, Japan
| | - Seiya Yamayoshi
- 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
| | - Yoshihiro Kawaoka
- 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
| | - Manabu Nemoto
- Equine Research Institute, Japan Racing Association, Tochigi, Japan.
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