Alveolar echinococcosis (AE) is caused by
infection with the larval stage of the tapeworm Echinococcus multilocularis. An increasing understanding of immunological events that account for the metacestode survival in human and murine AE
infection prompted us to undertake explorative experiments tackling the potential of novel preventive and/or immunotherapeutic measures. In this study, the immunoprotective and immunotherapeutic ability of recombinant EmP29
antigen (rEmP29) was assessed in mice that were intraperitoneally infected with E. multilocularis metacestodes. For vaccination, three
intraperitoneal injections with 20μg rEmP29 emulsified in
saponin adjuvants were applied over 6 weeks. 2 weeks after the last boost, mice were infected, and at 90 days post-
infection, rEmP29-vaccinated mice exhibited a median parasite weight that was reduced by 75% and 59% when compared to NaCl- or
saponin-treated control mice, respectively. For immunotherapeutical application, the rEmP29 (20μg)
vaccine was administered to experimentally infected mice, starting at 1 month post-
infection, three times with 2 weeks intervals. Mice undergoing rEmP29
immunotherapy exhibited a median parasite load that was reduced by 53% and 49% when compared to NaCl- and
saponin-treated control mice, respectively. Upon analysis of spleen cells, both, vaccination and treatment with rEmP29, resulted in low ratios of Th2/Th1 (IL-4/IFN-γ)
cytokine mRNA and low levels of
mRNA coding for
IL-10 and
IL-2. These results suggest that reduction of the immunosuppressive environment takes place in vaccinated as well as immunotreated mice, and a shift towards a Th1 type of immune response may be responsible for the observed increased restriction of parasite growth. The present study provides the first evidence that active immunotherapy may present a sustainable route for the control of AE.