Efficiency testing of foot--and--mouth disease vaccines prepared from strain "C" with different adjuvants.

Various oil adjuvants were tested for immunogenicity enhancing action in "C" type FMD monovaccine preparations. The following composition proved to be optimal in mouse tests: Bayl F 85%, Arlacel A 14% Tween 80 1%. As to the quantitative relations of antigen adjuvant, 40% oil to 60% antigen was the best among all proportions tested. Oil-adjuvanted vaccines failed to evoke an immune response in calves, but proved to be the preparation of choice for adult cattle. Oil containing and DEAE-dextran-containing vaccines had an equal efficiency in pigs; both conferred full protection on one in three pigs treated with 2.5-fold bovine doses. The number of vaccinated pigs was too small to permit definitive conclusions, but it seems clear that only oil dextran are efficient adjuvants of FMD vaccines for pigs, and that the antigen component of such vaccines should be increased considerably in order to obtain a greater potency.