Foot and Mouth Disease Virus Strain-specific Antibody Titres in Naturally Infected or Vaccinated Bulls in Kenya

Abstract

Foot-and-mouth disease (FMD) is a global viral infection that causes vesicular lesions in and around the mouth and feet, causing reluctance of animals to eat or move. In Kenya, bulls raised for AI receive vaccinations against FMD, but it is unclear if these animals experience vaccine-induced immunity. No research has been conducted to determine if animals in endemic areas develop natural immunity or whether animals in disease-free regions might be seropositive. This study aimed to determine the prevalence and levels of foot and mouth disease virus infection-triggered and vaccine-induced antibodies. A cross-sectional study was conducted on bulls farmed for AI production and vaccinated against FMD. Antibodies were quantified using a virus-neutralization test. One-way analysis of variance (ANOVA) and the Kruskal-Wallis test with Tukey and Dunn post-tests, respectively, were used to examine the data using the GraphPad InStat program. Additionally, the Spearman test was employed for correlation analysis and the t-test for intergroup differences analysis. A statistically significant P value was defined as less than 0.05. Findings showed protective antibody levels were present in 23%, 10.3%, 2.6%, and 7.7% of the animals in the FMD non-endemic region against the FMD virus strains O, A, SAT 1, and SAT 2, respectively. The protection provided by the O strain virus was significantly greater than that of SAT 1 (P = 0.01). In the FMD endemic area, all sampled animals showed protection levels at 100%, 100%, 100% and 29% for virus strains O, A, SAT 1, and SAT 2 respectively with the antibody titres showing significant differences (P < 0.05) for all the intergroup analysis except between strains O vs SAT 1 and A vs SAT 1 (P > 0.05). To conclude, the current research suggests that FMD may be making a comeback in the areas where the illness is not established. Furthermore, it seems that sperm recovery upon freezing is somewhat mitigated by FMDV-specific antibodies. The study advises monitoring FMD in areas where the illness is not endemic and confirms the current findings with larger sample sizes to enable more informed decision-making.