The vaccination potential of EMY162 antigen against Echinococcus multilocularis infection.

Alveolar echinococcosis is caused by infection with the larval stage of Echinococcus multilocularis. We recently identified a cDNA clone, designated as emy162, that encodes a putative secreted protein. EMY162 shares structural features with the EM95 antigen, which is a host-protective antigen. The amino acid sequence of EMY162 shows 31.4% identity to EM95 whereas these antigens are distinguishable with respect to their predicted secondary structure and antigenicity on Western blot analysis. RT-PCR analysis revealed that the gene expression of emy162 was significantly higher than that of em95 at each life-cycle stage. Recombinant EMY162 antigen induced a significant level of host-protection (74.3%) in experimental infection with E. multilocularis eggs in mice. Notably, recombinant EMY162 antigen showed significant reactivity to the sera from alveolar echinococcosis patients. These results may help in the development of a practical vaccine to reduce the level of alveolar echinococcosis in humans.