Evaluation of the phase-specific antibody response in water buffalo (Bubalus bubalis) after two doses of an inactivated phase I Coxiella burnetii vaccine

The control and management of Q fever outbreaks in ruminants are currently based on vaccination. Although buffalo (Bubalus bubalis) are intensively farmed in several countries and represent a reservoir for Coxiellosis, no evidence has been described regarding the efficacy of vaccination in this species. This work aimed to evaluate the humoral response, using appropriate phase-specific ELISAs, and the effects on abortion rate in buffalo by a field study. A total of 15 seropositive and 20 seronegative animals were vaccinated twice, three weeks apart, with a commercial phase I vaccine, and phase-specific antibodies were determined in the course of vaccination. Although anti-phase II antibody reactivity predominated after vaccination compared to phase I, both anti-phase I- and -phase II-antibody-reactivity significantly increased after the first (p = 0.001) and again after the second vaccination (p = 0.05). Seroconversion did not significantly depend on age or natural infection status. Once the vaccination cycle was completed, the herd study observed a reduced rate of abortion and placenta retention. Our data demonstrated that the vaccine principally induced a similar antibody response as in goats and sheep. These preliminary data appeared to support vaccination in buffalo, even in seropositive animals, although further studies are needed to better define the dynamics concerning seroconversion in this species.