assistant lecturer University of Veterinary Medicine Budapest Budapest, Pest, Hungary
Abstract: Background - In the last three decades West Nile virus (WNV) has become one of the most important viral encephalitic agents worldwide, causing significant numbers of human and equine cases every year by re-emerging in endemic areas and emerging into new territories. It is considered that following natural WNV infection, survivors develop life-long immune protection, however, the data are scarce in horses. Hypothesis - WNV infection provides long-term immunity in asymptomatically infected horses. Horses 25 asymptomatically infected, unimmunized, healthy client-owned horses from Hungary. Methods - In this prospective cohort study neutralizing antibody (nAb) levels of 25 horses were monitored for 5 consecutive years. Serum samples were collected yearly from the selected animals. First, a WNV IgG ELISA was performed, followed by a micro-virus neutralization assay. Results - Data were logarithmically transformed. The results are summarized in Table 1. Repeated measures ANOVA with a Greenhouse-Geisser correction determined that mean nAb levels differed statistically significantly across time points (F(2.645; 63.469) = 69.567; p < 0.01. Conclusion and clinical relevance - Our results indicate a significant time effect for anti-WNV titers (1. Figure). Since the level of nAbs provides the best correlate to Orthoflavivirus protection, our study indicates that horses might be unprotected against re-infection, therefore we recommend regular nAb titer testing in endemic areas.
