Effect of Reactive Oxygen Treatment on The Potency of Schistosoma Mansoni Worm Antigens in Induction of Resistance to Challenge Infection in Mice

The present study was conducted to investigate the effect of reactive oxygen (as NaOCI) treatment on the potency of S. mansoni whole worm antigens in induction of protective resistance to challenge homologous infection.
Five antigen preparations each treated with specific reactive oxygen concentrations were used. For each antigen preparation, mice were individually immunized, twice a week for 5 weeks, with 0.5 mg protein. Two weeks post immunization, mice were individually exposed by tail immersion to a challenge single dose of 100 S. mansoni cercariae. Two months later, animals were sacrificed and the degree of resistance was evaluated using worm burden, egg count, and liver pathophysiology and histopathology as indicative criteria.
The results obtained show that, immunization of mice with untreated antigens caused 26.3% reduction of the worm burden. Immunization of mice with treated antigens furthered the degree of resistance to a maximum of 62.9% by inoculation with antigen preparation treated with 100 ppm of NaOCI. Treatment with higher concentrations of hypochlorite did further the immunogenicity of worm antigens. In view of the relevant studies, however, the increase in the immunogenicity of the worm antigens by reactive oxygen treatment could be attributed to its disruptive effect on the carbohydrate coat thereby making some antigenic epitopes more accessible to the immune response.