Development of an assay using real time cell analysis for the measurement of equid herpesvirus 1 specific neutralizing antibody in horses after experimental infection or field vaccination

Background: Equid herpesvirus-1 (EHV-1) is one of the most important horse pathogens, which induces respiratory disease, myeloencephalopathy, abortion or still-birth. The measurement EHV-1 neutralising (EHV-1-VN) antibodies using a neutralisation assay (NA) gives an indication immune response horses in field. Objectives: To develop real time (RTNA) xCELLigence® technology for EHV-1-VN serums from experimentally infected vaccinated horses. Study design: Assay development and field trial. Methods: RTNA based on E. Derm cells was developed (n=48) taken daily (from Days 0 to 18 post-infection) ponies with strain. This method further evaluated (n=63) during EHV-1/-4 vaccination campaign. results were compared those obtained conventional NA RK13 cells. Two-fold serial dilutions incubated defined concentration KyD strain before infection normalised cell index monitored pre- post-infection technology. Conventional performed same experimental methodology cytopathic effects measured 72 hours post-infection. Results: Serum titres induced 50% (NT50) determined dose-response approach. increase NT50 similar titre (R²=0.79). Seroconversion detected between all both methods. values also positively correlated (R²=0.83). Main limitations: cross-reactivity will require investigation. Each used different cells. Conclusion: While consuming, requires subjective measurements provides semi-quantitative discrete ranked (e.g. 4, 8 etc.), automated, sensitive objective that reports continuous titres.