Potential role of interleukin 4 and 12 as adjuvants to tegumental antigen in a vaccination model for murine Schistosomiasis mansoni

ABSTRACT

Vaccine strategies represent an essential component for the future control of schistosomiasis. A variety of vaccines from different Schistosoma stages and different adjuvants have been identified to induce a level of host protective immune response as a trial to decrease morbidity. This work aimed to evaluate IL4 and IL12 as adjuvant for Schistosoma mansoni tegumental antigens [TA] vaccines prior to challenge of infection by S. mansoni. Sodium dodecyl sulfate [SDS] was selected for extraction of tegumental proteins. Ten groups of BALB/c mice [7 mice in each group] were classified into 4 control groups G1 non infected non vaccinated; G2 infected only; G3 given IL4 and G4 given IL12. The other 6 groups included G5 vaccinated by TA in a dose of 40 ug; G6 vaccinated by TA in a dose of 55 ug; G7 vaccinated by TA dose 40 ug and 100 ug of IL4; G8 vaccinated by TA dose 55 ug and 100 ug of IL4; G9 vaccinated by TA dose 40 ug and 100 ug of IL12 and G10 vaccinated by TA dose 55 ug and 100 ug of IL12. Booster doses were given for all groups after 2 and 4 weeks. Two weeks after the last booster dose mice in all tested groups were infected by S. mansoni cercariae [100 cercariae/mouse] via tail immersion technique. Seven weeks post infection [PI], mice were sacrificed and parasitological parameters [worm burdens, liver and stool egg counts] were studied to evaluate the impact of this vaccination model. Histopathological studies by Haematoxylin and Eosin [HE] and Feulgen stains were also performed. The use of IL12 as an adjuvant to TA revealed a significant reduction in worm burden, liver egg count and decreased ova count in stools as compared to their corresponding controls. In addition, histopathological examination of liver sections in the tested groups given IL12 showed decrease in the size and number of granuloma with decrease of liver cell apoptosis. On the other hand, both parasitological and histopathological results of the tested groups given to IL4 as an adjuvant to TA were contradictory. IL 12 potentiated the protective effect of S. mansoni tegumental antigen vaccine and posed as a useful adjuvant, while IL4 was less effective. TA is an efficient model for future studies in molecular identification of novel candidate tegumental proteins