Antibody Responses to a Reverse Genetics-Derived Bivalent Inactivated Equine Influenza Vaccine in Thoroughbred Horses.
Authors: Ohta Minoru, Bannai Hiroshi, Kambayashi Yoshinori, Tsujimura Koji, Tamura Norihisa, Iwamoto Yohei, Wakuno Ai, Yamayoshi Seiya, Kawaoka Yoshihiro, Nemoto Manabu
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Equine influenza vaccine development requires periodic strain updates to maintain protective immunity, and reverse genetics (RG)—a laboratory method for generating viruses with specific genetic characteristics—offers a potentially faster alternative to traditional wild-type virus isolation for vaccine production. Researchers compared antibody responses in Thoroughbred yearlings and adult horses vaccinated with either a newly developed bivalent RG-derived vaccine containing updated Florida sub-lineage strains (Ibaraki/2007 and Yokohama/2010) or a commercially available conventional vaccine using the same strains; primary vaccination courses comprised two doses four weeks apart in yearlings, whilst vaccinated adults received a single booster dose. Both vaccine formulations produced equivalent haemagglutination inhibition antibody responses in both age groups, with similar kinetics and titre patterns, indicating the RG vaccine delivered immunogenicity comparable to the established commercial product. These findings have significant implications for vaccine manufacturers and regulatory bodies, as they demonstrate that RG-derived multivalent vaccines could expedite the introduction of emerging strain variants into vaccination programmes, potentially reducing the time lag between field virus evolution and vaccine availability—a critical consideration given equine influenza's capacity for antigenic drift. For practitioners, this research supports confidence in next-generation RG-based vaccines should they become commercially available, whilst reinforcing the importance of maintaining vaccination protocols aligned with current circulating strains.
Read the full abstract on PubMed
Practical Takeaways
- •Reverse genetics-derived EI vaccines provide equivalent protection to traditional commercial vaccines, offering a platform for rapid vaccine strain updates when new equine influenza variants emerge
- •Both primary and booster vaccination schedules with RG-derived bivalent vaccines achieve expected immune responses in Thoroughbreds, supporting their use in routine vaccination programs
- •RG vaccine technology enables flexibility in multivalent vaccine development, potentially improving response to evolving equine influenza strains in field populations
Key Findings
- •Bivalent reverse genetics-derived inactivated EI vaccine elicited hemagglutination inhibition antibody responses equivalent to commercially available vaccine in both yearlings (7 RG vs 9 CO) and adult horses (18 RG vs 14 CO)
- •Primary vaccination course in unvaccinated yearlings showed similar antibody response patterns between RG and CO vaccine groups over four weeks
- •Booster vaccination in previously vaccinated adult horses demonstrated equivalent immunogenicity between RG and CO vaccine groups
- •RG viruses with HA and NA genes from Florida sub-lineage clades 1 and 2 strains proved suitable for multivalent vaccine formulation