ABSTRACT
The emerged resistance to praziquantel [PZQ] in treatment of schistosomiasis necessitates the search for novel drugs. Cysteine proteases inhibitors [CPIs] have shown promising results in either parasitic infections or non-parasitic diseases. The study aimed to evaluate the therapeutic effects of two CPIs: phenyl vinyl sulfone [PVS] and valproic acid [VA] in comparison to PZQ in S. mansoni-experimentally infected mice. Swiss albino mice were experimentally infected with S. mansoni cercariae. The mice were divided into 4 groups [25 mice each], and G1 mice were not treated and used as control group. Mice of G2, G3 and G4 were treated by the evaluated drugs [PVS, VA and PZQ, respectively] at the end of the 6[th] week post infection [PI]. The evaluating parameters were 1] fecal egg count, 2] worm burden, 3] tissue egg count, 4] oogram pattern and 5] hepatic granuloma number and size. The results showed that by the end of 10[th] week PI, PZQ was the most effective drug resulting in decrease worm burden in the portal vein, increase proportion of dead eggs in the oogram pattern, decrease in the hepatic egg count and decrease in granuloma numbers. On the other hand, the granuloma diameter was smallest in PVS treated group compared to the other groups. CPIs have a relative fair favorable therapeutic outcome on schistosomiasis mansoni with the advantage of being novel drugs with no therapeutic resistance, especially PVS which showed an added specific anti-immunopathological effect reflected by the small hepatic granuloma size