Experimental Trial with a Heat-Shocked Protoscolex Extract as a Vaccine Candidate for Protection Against Hydatid...

Cystic echinococcosis is distributed worldwide and is an important public health challenge in many countries. The present study was an experimental trial to use hydatid antigens derived from viable protoscoleces cultivated at 37 and 45°C for 4 h as a vaccine candidate for protection against hydatid infection.

Balb/c mice were immunized with hydatid antigens extracted from protoscoleces exposed to 37 and 45°C as well as partially purified hydatid antigens containing 30, 60, and 90 µg of heat shock protein 70 administered with or without an adjuvant.

Crude antigens from protoscoleces exposed to 37°C conferred non-significant immunity with protection and reduction rates that ranged from 0% to 25% and 77.69% to 98.38%, respectively. In mice receiving crude antigens from protoscoleces exposed to 45°C, the protection and reduction rates ranged from 0% to 66.66% and 94.62% to 98.92%, respectively. The purified antigen from protoscoleces exposed to 45°C conferred significant immunity with absolute protection observed in mice immunized with 60 and 90 µg of the antigen combined with the adjuvant. Immunological parameters (anti-hydatid antibody titer and lymphocyte transformation %) showed a negative correlation with the number of cysts. The assessment of renal and liver functions showed non-significant differences (p>0.05) in comparison with the liver and renal functions of non-immunized mice of the negative control group.

Purified hydatid antigens containing heat shock protein 70 confer high levels of protection against hydatid infection in mice.