Immunization with CRT-Induced Protective Immunity against Infection in BALB/c Mice

Alveolar echinococcosis (AE) is a severe parasitic zoonosis caused by the larval stage of . The identification of the antigens eliciting acquired immunity during infection is important for vaccine development against infection. Here, we identified that calreticulin (CRT), a ubiquitous protein with a Ca-binding ability, could be recognized by the sera of mice infected with . The native CRT was expressed on the surface of larvae as well as in the secreted products of metacestode vesicles and protoscoleces (PSCs). The coding DNA for CRT was cloned from the mRNA of the metacestode vesicles and a recombinant CRT protein (rCRT) was expressed in . Mice immunized with soluble rCRT formulated with Freund's adjuvant (FA) produced a 43.16% larval vesicle weight reduction against the challenge of PSCs compared to those that received the PBS control associated with a high titer of IgG, IgG1 and IgG2a antibody responses as well as high levels of Th1 cytokines (IFN-γ and IL-2) and Th2 cytokines (IL-4, IL-5 and IL-10), produced by splenocytes. Our results suggest that CRT is an immunodominant protein secreted by larvae and a vaccine candidate that induces partial protective immunity in vaccinated mice against infection.