Abstract: 3A, 3B, 3C gene fragments were successfully subcloned from 3ABC gene of the foot-and-mouth disease virus ( FMDV ) Taibao strain and their expressing plasmids were constructed by inserting the target gene fragments into Pgex-4T-1 or 24B11 vectors，respectively. The expressed proteins were analysed by Western blotting. The results showed that the 3A and 3B expressing products could specifically react with FMDV positive serum while the reaction of the 3C product was negative. Indirect ELISAs were developed using purified 3A and 3B proteins as antigens respectively, and 4 groups of background-known cattle sera were tested. Negative results were obtained for the non-vaccinated control group and the vaccinated group. On the contrary, positive results were achieved for the infected group and part of the infected post-vaccination group. In the infected group and infected post-vaccination group, the longest duration of the antibodies against 3A and 3B lasted for at least 90 days. The earliest appearing times of 3A, 3B antibodies were 5th and 10th days after infection, respectively.

Key words: Foot-and-mouth disease virus, Non-structural protein, Gene clone and expression, Antibody dynamic