Abstract: Specific primers were designed and synthesized based on the reported EgA31 gene of Echinococcus granulosus （GenBank Accession No. AF067807）. Total RNA was extracted from E. granulosus and its EgA31 gene was amplified by reverse transcription-polymerase chain raction （RT-PCR）. The PCR product was purified and cloned into plasmid pUCM-T，then transformed into Escherichia coli DH5α. The recombinant plasmids were screened and identified by digestion with restriction enzyme and PCR amplification. The positive recombinant plasmid pUCM-T/EgA31 was confirmed by sequencing and homology comparison. Five parameters and methods were used to predict B-cell epitopes in amino acid sequence of EgA31. The amplified DNA fragment （636 bp） had an identity of 100% with the EgA31 gene sequence of E. granulosus. B-cell and T-cell epitopes of EgA31 were probably at or adjacent to 32-79，79-95，105-124 and 141-154 in its amino acid sequence.

Key words: Echinococcus granulosus, pET30a-EgA31, Antigenic epitope, Bioinformatics