Vaccination with rEGVac elicits immunoprotection against different stages of Echinococcus granulosus life cycle

Vaccination against dog–sheep transmission cycle is necessary to control cystic echinococcosis (CE) infection. A novel multi-epitope recombinant vaccine (rEGVac) was developed for the immunization of both sheep and dogs against Echinococcus granulosus, simultaneously. The His-tagged rEGVac was designed based on three E. granulosus protective antigens (EG95, EgEnolase, and Eg14-3-3), cloned into the pET-22b+ vector, and expressed using Escherichia coli BL21 (DE3). Once purified and formulated with Freund's (complete and incomplete) adjuvants, it was assessed in 15 dogs and 15 sheep, simultaneously (five experimental groups and three animals in each group). The vaccine was injected by two subcutaneous doses 28 days apart. To evaluate the rEGVac efficacy, species-specific antibodies (Abs) (i.e., IgG, IgE) and cytokine (IL-4) were analyzed. Moreover, hydatid cysts, adult worms, and pathological samples of animals challenged with E. granulosus protoscoleces (PSCs) were studied. Specific IgG, IgE, and IL-4 were increased after each round of vaccine injection, while the total number of hydatid cysts was reduced (~85.43%). The vaccinated dogs with the rEGVac showed high immunoprotection efficacy (~100%). The rEGVac demonstrated high immunoprotection efficacy against E. granulosus especially in dogs, however, its efficacy in sheep was not as high as dogs. The rEGVac is proposed as a protective vaccine modality in both dogs and sheep.