Using four clones isolated from Echinococcus multilocularis cDNA library with alveolar echinococcosis (AE) patient sera, various antigens were expressed as ThioHis tag-fused protein. Recombinant EmII/3 antigen was produced as the five fragments divided into the N-terminal (#5 and #5s), the central (#6 and #6s) and the C-terminal domain (#7). Immunoblot analysis revealed that the #7 showed significant reactivity whereas those of #5 and #5s were relatively low. The #6 and #6s also showed lower reactivity than that of #7, although the two minor bands of #6 reacted with every serum. These results suggested that an immunodominant region of EmII/3 locate within the C-terminal one third. The #8s recombinant antigen, Ser23-Glu176 of actin filament fragmenting protein (AFFP), apparently reacted with the AE patient sera, while the #1 antigen synthesized as a full-length antigen BI did not show such high reactivity. Thus, #7 and #8s antigens showed significant potential for use in immunodetection of AE. In addition, the specific antibodies against #7 and #8s reacted with specific antigens in crude extract of E. multilocularis cyst, indicating that these antigens retained antigenicity common to native EmII/3 and AFFP, respectively.