The immunogenic effect of purified antigens of B. alexandrina against S. mansoni in experimental animals (II) as measured by the histopathological changes in the liver.

It can be safely said that up till now, no method of vaccination (including recent genes encoding vaccines) has yet proved to be totally effective since they gave partial and low levels of protection against S. mansoni infection. The objective of this work is to try testing the immunogenic effect of two purified non infected B. alexandrina hepatopancreas through histopathological changes in liver of Swiss albino mice (15-20 gm). Gel filtration chromatography was used to fractionate the crude antigen into five fractions followed by re-fractionation and determination of their molecular weights by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Four dilutions of Fiv (20000-29000 daltons) and Fv (20000-24000 daltons) were injected in two groups of mice (33 each) at weekly intervals and another control group was injected with phosphate buffer saline (PBS) in the same manner. Sacrification was done seven weeks from infection with 100 S. mansoni cercariae through immersion method. The results revealed that there is marked histopathological changes in liver of the control group in comparison to the two vaccinated groups which appear more or less normal with slight inflammatory infiltrate.

The immunogenic effect of purified antigens of B. alexandrina against Schistosoma mansoni in experimental animals (I) as measured by worm load and viability of ova.

Current stratigies for the control of schistosomiasis are based primarily on chemotherapy but successful vaccination against infection has been also demonstrated in several host parasite models. In this study, the immunogenic effect of two purified antigens (Fiv 20-29 000 daltons & Fv 20-24 000 daltons) extracted from non infected hepatopancreas of B. alexandrina as measured by worm load, state of copulation and viability of ova in tissues. The antigens were prepared using gel filtration chromatography and their molecular weights were estimated through sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Four dilutions from each antigen were prepared and injected in two groups (33 each) of Swiss albino mice at weekly intervals. A control group was injected with phosphate buffer saline (PBS) in the same manner. All mice were injected with 100 cercariae using immersion method. Sacrification was done regularly after 7 weeks of injection. On the basis of worm load, Fiv gave protection of 44% while Fv gave only 36%. The number of worms in copula was significantly reduced and they became delicate, fragile, stunted and malformed. Both antigens gave a significant reduction in total viable eggs in tissues.