The result of PD₅₀ test.

All of cattle were challenged with 10,000 BID50 of Asia I/HNK/CHA/05 after vaccination by inoculating the equivalent of a total of 10,000 BID50 of Asia I/HNK/CHA/05 intradermally into two sites on the upper surface of the tongue. All cattle were observed for 10 days. Vaccinated animals are protected if they do not develop lesions on the feet and areas other than the injection sites on the tongue. Rate of protection (%) = number of cattle no lesions/total number of cattle. The PD50 value was calculated by the Reed-Muench method.