Objective: To investigate the immune protection of the recombinant membrane protein(45M) against larvae of Taenia multiceps in sheep.
Methods: Twelve sheep were randomly divided into immune group and control group, and each sheep was immunized four times (three weeks interval) respectively with 50 microg recombinant 45M or GST emulsified with adjuvant. Serum samples were collected at pre-immunization and certain time after immunization, and were analyzed for IgG and IgM by ELISA. At the 105th day after the final inoculation, each sheep was orally challenged by 5000 eggs of T. multiceps. Two weeks after infection, the sheep were sacrificed, serum samples were collected, and number of cysts in brain tissue was counted. Activated oncospheres were cultured with 10% sera of immune group or control group, and observed by light microscopy.
Results: The mean number of cysts was 1.5, and the average diameter of the cysts was 2.2 mm. Compared with control group, the reduction rate of cysts in immunized sheep was 68.9%. At the 72th hour after culture with serum of immunized sheep, about 90% oncospheres were killed by antiserum, and the oncospheres began to shrink or expand, and internal structure became fuzzy. ELISA showed that after final immunization (the 9th week), the levels of IgG in sera of immune group (2.32+/-0.76) were significantly higher than those of the control (0.70+/-0.42) (t=4.47, P<0.01). At the 24th week the levels of IgG and IgM in sera of immune group (1.53+/- 0.81, 0.90+/-0.26) were significantly higher than those of the control (0.64+/-0.43, 0.43+/-0.15) (P<0.01).
Conclusion: The recombinant 45M can induce certain humoral immune response.