Evaluation of Immune response to Foot and Mouth Disease Polyvalent Vaccine and its Compatibility with Differentiating Infected from Vaccinated Animal (DIVA) Test in Cattle, Bishoftu town, Ethiopia

The research was conducted in Bishoftu town, Oromia Regional State, from October 2019 to June 2020, with the aim of Differentiating Infected from Vaccinated Animals (DIVA) and assessing the immune response of polyvalent FMD (Foot and Mouth Disease) vaccine. The study involved 34 cattle in a longitudinal study, divided into two groups: 29 vaccinated and 5 unvaccinated. The vaccinated cattle received an inactivated polyvalent FMD virus vaccine produced by the National Veterinary Institute (NVI). Blood samples were collected on days 0, 14, 21, 35, 80, and 125 after vaccination and tested using Virus Neutralization Test (VNT) and 3ABC ELISA. The results showed a significant increase in neutralizing antibodies against structural proteins in all vaccinated cattle on day 14 after vaccination for all three serotypes. (A/ETH/21/2000, p = 0.015; O/ETH/38/2005, p = 0.017; SAT2/ETH/64/2009, p = 0.007). On day, fourteen of post-vaccination vaccinated group showed immune response equal or above 1.5 log10 in a proportion of 69%, 73% and 94% for serotype A/ETH/21/2000, O/ETH/38/2005 and SAT2/ETH/64/2009 respectively. The status of raised antibody titer on day 125 post-vaccination showed decreasing by 14%, 18% and 4% for serotype A/ETH/21/2000, O/ETH/38/2005 and SAT2/ETH/64/2009 respectively. The DIVA test, or 3ABC ELISA, used to differentiate infected from vaccinated animals, revealed the absence of immune response to the Non-structural protein (NSP) in the vaccinated cattle group. Conversely, the unvaccinated group showed no recorded antibody titer to both structural and non-structural proteins. In summary, the commercially available FMD vaccine, comprising serotype A, O, and SAT2, triggers an immune response to the structural protein rather than the non-structural protein after the initial administration. This outcome implies that FMD vaccines from the National Veterinary Institute align with the DIVA test. Nevertheless, additional efforts may be necessary to bolster the strength and duration of the vaccine-induced immune response.