Correlation Between Serum Amyloid A and Antibody Response to West Nile Virus Vaccine Antigen in Healthy Horses.
Authors: Skipper Lauren, Pusterla Nicola
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Serum Amyloid A and West Nile Virus Vaccine Response in Horses Establishing reliable markers of effective vaccination is crucial for equine practitioners tasked with assessing herd immunity, yet current post-vaccination monitoring relies heavily on antibody titres alone. Skipper and Pusterla investigated whether peak serum amyloid A (SAA) concentrations—a non-specific acute phase protein—could serve as a practical indicator of adequate immune response following West Nile Virus vaccination in 60 clinically healthy horses, measuring SAA at multiple timepoints (pilot group: 0–168 hours; main group: 0 and 72 hours) and serum neutralisation antibodies pre- and 30 days post-vaccination. Whilst 90% of horses mounted a measurable SAA response to vaccination, there was no significant correlation between peak SAA concentration and antibody titre fold changes, with only 57% of the population showing increased WNV antibody titres, 30% showing no response and concerningly 13% demonstrating negative fold changes after vaccination. Age emerged as a significant confounding variable, with younger horses producing notably higher SAA responses (P = 0.0008), suggesting that age-stratified interpretation of acute phase responses may be necessary. These findings challenge the assumption that observable inflammatory markers reliably predict seroconversion and highlight substantial individual variation in vaccine take, warranting further investigation into which horses fail to respond adequately and whether revaccination or alternative protocols might improve population-level WNV immunity.
Read the full abstract on PubMed
Practical Takeaways
- •SAA measurements cannot be used as a reliable indicator of successful immune response to WNV vaccination in horses—serological testing remains necessary to verify antibody development
- •Expect variable antibody responses to WNV vaccination in your practice; roughly 40% of vaccinated horses may not develop adequate antibody titers despite apparent immune activation
- •Younger horses generally mount stronger acute inflammatory responses to WNV vaccination; consider age-related factors when evaluating vaccination outcomes
Key Findings
- •90% of horses showed increased SAA in response to WNV vaccination, but SAA peak did not correlate significantly with antibody titer fold changes
- •Only 57% of vaccinated horses developed increased WNV antibody titers, while 30% showed no change and 13% showed negative fold changes post-vaccination
- •Age significantly inversely correlated with SAA response to vaccination (P = 0.0008), with younger horses mounting stronger acute phase responses
- •SAA response to WNV vaccination does not reliably indicate development of protective antibody response