UV-attenuated Schistosoma japonicum cercariae induce immune responses in mice that ameliorate liver damage during subsequent infection with normal cercariae

Objectives To investigate protection against schistosomiasis provided by UV-attenuated cercariae of Schistosoma japonicumin C57BL/6and DBA mice. Methods Reductions in the worm burden as a result of attenuating cercariae with different UV intensities(A:400μw/cm2 UV for 1 min,B:422μw/cm2 UV for 40sec)were evaluated in C57BL/6 and DBA mice.In addition,egg production and granuloma sizes were compared. Results C57BL/6mice immunized with cercariae attenuated with 400μw/cm2 UV for 1min had a reduced worm burden of-0.60% while similar mice immunized with cercariae attenuated with 422μw/cm2 UV for 40sec had a reduced worm burden of 0.02%.The levels of egg reduction were 2.70% and 11.37%,respectively.Similarly immunized DBA mice had a reduced worm burden of 29.10%and 25.70%,respectively,and levels of egg reduction of 59.50% and 69.50%,respectively.A significant reduction in granuloma size was observed in C57BL/6mice immunized with cercariae attenuated with 422μw/cm2 UV for 40sec,in DBA mice immunized with cercariae attenuated with 400μw/cm2 UV for 1min,and in DBA mice immunized with cercariae attenuated with 422μw/cm2 UV for 40sec. Conclusion UV-attenuated S.japonicumcercariae induced a low level of protection against Schistosoma japonicum and moderately reduced the granuloma size in C57BL/6 and DBA mice.Immunization with UV-attenuated S.japonicumcercariae induces an immune response in mice that ameliorates liver damage during subsequent infection with normal cercariae.