DEMONSTRATION OF ANTIBODIES AGAINST FOOT-AND-MOUTH-DISEASE VIRUS (FMDV) TYPE-O AND ASIA-1 IN NON-DESCRIPTIVE CROSSBRED CALVES

Sera from non-descriptive crossbred calves were screened for the prese nce of neutralizating antibodies against FMDV type 0 and Asia-1 for a period up to 215 days. The antibody titer of 16 remained constant up t o 215 days against type 0 and up to 190 days against type Asia-1 virus in some animals. In majority of the animals the antibody titers remai ned constant up to three months. The possible reason for a frequent br eakdown of immunity in the vaccinated animals even 3 - 4 months after vaccination could be the fact that the calves were vaccinated repeated ly at their very early age with an ill effect of immunization in the p resence of persisting antibodies.