We conducted this study to determine the level of immunity after vaccination of lambs with whole body Echinococcus granulosus. To do so, 200 mature E. granulosus parasites, which were kept in 10% formaline for 8 months, were obtained from the Department of Parasitology, School of Veterinary Medicine, Ferdowsi University of Mashhad. The soluble protein of the parasite was prepared. The sample was homogenized in a blender, sonicated on ice and then centrifugated for 15 min at 10,000 g. Final yield was kept at -20ºC until used. Eight 4–6-month-old lambs of mixed sex, were divided into 2 equal groups; each lamb in the test group was vaccinated subcutaneously in the neck with 2 ml of the vaccine (1 mg of whole body of E. granulosus protein dissolved in 1 ml of PBS plus 1 ml of Freund’s complete adjuvant (FCA)). The control lambs were vaccinated only with adjuvant in PBS. Lambs were re-vaccinated four weeks after the first vaccination with the same preparation except that FCA was replaced by Freund’s incomplete adjuvant (FIA). Three weeks later, each lamb was administered a challenge infection dose of 2000 protoscolices intraperitoneally and 10 adult E. granulosus. After 7 months, all lambs were killed and examined for hydatid cysts. We found two cysts in the liver and and one in the lung of only one of the vaccinated lambs. The number of cysts in vaccinated lambs were significantly lower than that in the control group (P<0.001). This means that the protective immunity in lambs with whole body of E. granulosus was approximately 90%.

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