Abstract

Alveolar echinococcosis (AE) is a severe parasitic zoonosis caused by the larval stage ofEchinococcus multilocularis. The identification of the antigens eliciting acquired immunity during infection is important for vaccine development againstEchinococcusinfection. Here, we identified thatE. multiloculariscalreticulin (EmCRT), a ubiquitous protein with a Ca2+-binding ability, could be recognized by the sera of mice infected withE. multilocularis. The nativeEmCRT was expressed on the surface ofE. multilocularislarvae as well as in the secreted products of metacestode vesicles and protoscoleces (PSCs). The coding DNA forEmCRT was cloned from the mRNA of theE. multilocularismetacestode vesicles and a recombinantEmCRT protein (rEmCRT) was expressed inE. coli. Mice immunized with soluble rEmCRT formulated with Freund’s adjuvant (FA) produced a 43.16% larval vesicle weight reduction against the challenge ofE. multilocularisPSCs 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 thatEmCRT is an immunodominant protein secreted byE. multilocularislarvae and a vaccine candidate that induces partial protective immunity in vaccinated mice againstEchinococcusinfection.Keywords:Echinococcus multilocularis;alveolar echinococcosis;calreticulin;vaccine;protective immunity