Comparison of the serological responses in pigs after oral vaccination against classical swine fever using two different types of bait.

As a complementary tool for control of classical swine fever (CSF) in wild boar vaccine baits containing the attenuated and highly efficacious C-strain have been distributed in several countries. Several issues have been identified with the present available bait system, like relatively low uptake by piglets, melting point and mechanical stability. Hence, an alternative bait system has been developed including a more thermo-stable bait matrix and vaccine container. In the present study, the attractiveness and the capability of inducing an adequate immune response of this new bait system (IP) was compared with the present available product (CP) in two groups of 25 pigs each. The pigs of each group were offered the respective bait individually, and the animals were bled at 14 days prior to vaccination and 28 - and 42-days post vaccination (dpv). Blood samples were examined for antibodies in ELISA and virus neutralizing test (VNT). Two and one animal in the CP and IP group refused to consume the bait, respectively. The IP was significantly more rapidly consumed than the CP (p = 0.021). All animals that consumed a bait in both groups tested seropositive in VNT (≥10 ND₅₀) at 28 dpv and reached antibody titers above the threshold for protective immunity (32 ND₅₀) at 42 dpv. Hence, it can be concluded that the new bait system can induce an adequate immune response in pigs after the consumption of a single bait.