Epizootiological investigation of equine herpesvirus type 1 infection among Japanese racehorses before and after the replacement of an inactivated vaccine with a modified live vaccine.
Authors: Bannai Hiroshi, Tsujimura Koji, Nemoto Manabu, Ohta Minoru, Yamanaka Takashi, Kokado Hiroshi, Matsumura Tomio
Journal: BMC veterinary research
Summary
# Editorial Summary: EHV-1 Vaccination Strategy in Japanese Racehorses Equine herpesvirus type 1 remains a significant cause of winter pyrexias in Japanese racing populations, prompting the Japan Racing Association to switch from inactivated to modified live EHV-1 vaccines in 2014–2015. The researchers evaluated this strategic change by comparing the virus-neutralising antibody responses generated by both vaccine formulations and conducting an epidemiological survey of EHV-1 infection patterns at the JRA Ritto Training Center across seven winter seasons (2010–2017). The modified live vaccine produced superior and more durable antibody titres compared to the inactivated product, with corresponding reductions in both infection incidence and clinical disease severity in the post-switch period. These findings have direct relevance for vaccination protocols in high-density racing yards where EHV-1 circulation is endemic, suggesting that live attenuated vaccines may offer more robust population-level protection despite inactivated vaccines' theoretical safety advantages. Practitioners should consider these immunological and epidemiological outcomes when advising on EHV-1 prevention strategies, particularly in facilities where consistent winter outbreaks have been problematic.
Read the full abstract on PubMed
Practical Takeaways
- •Modified live EHV-1 vaccines generate superior antibody responses compared to inactivated vaccines, potentially providing better protection during winter outbreaks in racing facilities
- •Vaccine choice significantly impacts herd immunity dynamics—switching from inactivated to live vaccine warrants monitoring of outbreak patterns in your facility
- •If using modified live EHV-1 vaccine, expect improved VN antibody titers but ensure biosecurity protocols account for potential viral shedding from vaccinated horses
Key Findings
- •Modified live vaccine induced significantly higher virus-neutralizing antibody titers compared to inactivated vaccine
- •EHV-1 infection outbreak incidence was evaluated before and after vaccine switch at JRA Ritto Training Center from 2010-2017
- •Vaccination strategy change from inactivated to modified live vaccine altered immunological response in Japanese racehorses