Immunization of lambs against infection with Echinucoccus Granulosus using protoscolices and hydatid fluid antigens

In the present study, protoscolices and hydatid fluid were prepared from livers or lungsof sheep with hydatid cyst in sterile conditions. The protein concentration of samples was thenmeasured by Bradford method. 12 lambs 4 - 6 months of age of mixed sex were randomlyallocated to 3 groups of 4 lambs. Each lamb in groups 1 and 2 was immunized subcutaneouslyin the neck with a 2 - ml dose of vaccine (1 mg of protoscolex and hydatid fluid proteins dissolvedin 1 ml of PBS) and emulsified with an equal volume of Freund's complete adjuvant (FCA)respectively. Control lambs were immunized with adjuvant in PBS. Lambs were boosted at day28 with the same preparation except that FCA was replaced by Freund's incomplete adjuvant(FIA). Three weeks after the second immunization, each lamb received a challenge infectionwith 2000 protoscolices intraperitoneally and 10 adult E. granulosus. All lambs were euthanizedafter 7 months and examined for hydatid cysts. Results showed that, the number of cysts inimmunized lambs with protoscolices were lower than in control group and also the number ofcysts in immunized lambs with hydatid fluid antigen was significant (p<0.05). This resultindicated that the protective immunity in lambs with protoscolices and hydatid fluid was 54.5%and 75.75% respectively.

Keywords:

Echinococcus granulosus , protoscolex , hydatid fluid , immunization , lamb