Abstract: To develop SAT Ⅱ-specific FMDV serological diagnostic method, six peptides verified to be with good antigenicity in the former study were linked by flexible amino acid linker GS or PPPS, the related nucleotides were synthesized and expressed in vitro by cloning into vector pGEX-6P-1 and inducing with IPTG. The specificity of the expressed GST fusion protein was examined by SDS-PAGE and Western blotting analysis using anti-GST sera and antiserum against SAT Ⅱ FMDV.The fusion protein was purified by GST affinity chromatography purification system and excised on column. The antigenicity of purified protein VP1-VP3 was examined using the developed indirect ELISA assay. PCR and DNA sequencing results showed that the gene VP1-VP3 had been integrated accurately into vector pGEX-6P-1. SDS-PAGE showed that the fusion protein was 38.3 ku in size and existed in the form of insoluble inclusion body. Western blotting analysis results indicated that the fusion protein was with good specificity. Indirect-ELISA results showed that the VP1-VP3 protein had good antigenicity. The successful expression of mass-peptide will lay the foundations for the latter establishment of serological diagnostic methods for SAT Ⅱ FMDV inspection.

Key words: foot-and-mouth disease virus; South-Africa serotype; antigenic epitope; expression; antigenicity analysis