The Immunogenicity of a Foot-and-Mouth Disease Virus Serotype O Vaccine in Commercial and Subsistence Cattle Herds in Zambia

The recent introduction of foot-and-mouth disease virus serotype O (O/EA-2 topotype) in Southern Africa region has changed virus dynamics and the FMD vaccine requirements. This study describes an assessment of the heterologous antibody responses induced by O Manisa vaccine (three PD50/dose) against a representative O/EA-2 virus collected from an FMD outbreak in Zambia. Commercial and subsistence cattle herds were monitored following vaccination, where the benefits of employing a double vaccination schedule were compared to single-dose vaccination. Testing using virus neutralisation showed cattle that received two vaccine doses had a mean reciprocal log virus neutralisation titre of 2.02 (standard error [SE] = 0.16, n = 9) for commercial herds and 1.65 (SE = 0.17, n = 5) for subsistence herds , 56 days after first vaccination (dpv). Significantly lower mean titres were observed for single-dosed commercial herds (0.90, SE = 0.08, n = 9) and subsistence herds (1.15, SE = 0.18, n = 3), 56 dpv. Comparison of these results and those generated by solid-phase competitive ELISA by cohen’s kappa coefficient observed a statistically significant (ρ = 0.598 for 1:10 dilution, and ρ = 0.562 for 1:30 dilution of SPCE % inhibition results, p < 0.001 for both dilutions) positive correlation.