We have shown previously that primary infection of sheep with hydatid fluid, protoscolex and whole body of Echinococcus granulosus is partially protective against subsequent challenges. The immunogenicity of three proteins was investigated in sheep. Sixteen lambs 4 – 6 months of age of mixed sex, were divided into 4 groups of 4 lambs (three immunized and one control group). Twelve lambs as immunized groups received 2 mg of hydatid fluid, protoscolex and whole body of E. granulosus antigens dissolved in 1 ml of PBS per immunization for each sheep, respectively. Freund,s complete adjuvant (FCA ) as an adjuvant was mixed with antigens to form a water-in-oil emulsion giving a dose of 2 ml which was inoculated subcutaneously on either side of the scapula on day 1 of the trial. Each control lamb was inoculated with a total of 2 ml of PBS emulsified in an equal volume of FCA. Lambs were boosted on day 28 with the same preparation as described above except that FCA was replaced by Freund,s incomplete adjuvant (FIA). After immunization, serum was collected at different time periods and serum antibodies were tested by ELISA. When sheep were immunized with different antigens, some of them produced little antibody to hydatid fluid by day 28 after first immunization. However, all the immunized sheep showed a strong response to antigen at day 49 that was 21 days after second immunization, as compared to the control group. The results showed that three different antigens which were used in immunization of sheep have common antigens.

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