Preliminary studies on Immunopathogenesis of S. mansoni in Grivet monkeys (Cercopithecus aethiops) Vaccinated with 20Krad Irradiated S. mansoni cercariae

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Addis Ababa University


In this study, we established S. mansoni infection in the primates, Cercopithecus aethiops aethiops (Grivet monkeys). Most of the clinical manifestations in human schistosomiasis like fever, bloody diarrhea, loss of appetite, and swollen lymph nodes were noted in the experimentally infected monkeys. Due to the absence of the appropriate animal models, there is little understanding of immune-response development in schistosomiasis, which has created a challenge for designing an effective anti-schistosome vaccine. Repeated intraperitonial immunization of the monkeys with 20Krad irradiated S. mansoni cercariae resulted in a relatively less granulomatous reaction and EPG (P<0.05) than in the controls. The difference in the total adult worms is statistically not significant (P>0.05) between both groups of monkeys. In primary infection, IL-4 was significantly (p = 0.03) raised in the immunized monkeys, and for the same group an insignificant (P > 0.05) increases in IL-10. However, ova excretion did not have an influence on cytokines, except for the controls both IL-4 and IL-10 are significantly increased (p < 0.05). Both IL-12 and INF- levels were lower after ova excretion in the controls, but the inflammatory TNF- has increased (P = 0.049) and these can be associated with more liver pathogenesis in the group. The immunization has minimized egg production and the development of granuloma in the liver of Grivet monkeys. Thus, this work has underlined the potential importance of the monkeys as the helpful models and provided a direction for research studies of drugs or anti-schistosome vaccines.