Abstract
BACKGROUND: The freshwater snails Biomphalaria alexandrina and Bulinus trancatus are key contributors to the transmission of S. mansoni and S.haematobium, respectively, for being their intermediate hosts. OBJECTIVES: This research study aimed to investigate the potency of the nucleoproteins (NPs) extracted from both snail species on the host immune reactions as an approach to developing a potential vaccine. METHODS: Three groups of six-week-old Swiss-Webster mice (n = 18; 15-20 g each) were injected intraperitoneally for three consecutive weeks with single doses (once a week) of B. alexandrina, B. truncatus, or a mixture of their nucleoproteins (50 µg each). On day 21st, the nucleoprotein-treated mice altogether, with six more mice, received subcutaneously S. mansoni cercariae (60/mouse). Eight weeks later, the experimental mice were sacrificed for evaluation of certain parasitological, molecular and immunological responses. RESULTS: The data of mice immunized with the various types of nucleoproteins showed a significant increase of FAS/R gene expressions in hepatic tissues and anti-IgG antibody levels in sera on the one hand and a significant decrease of worm loads and β-actin/R gene expression levels on the other hand when compared to the infected control mice. CONCLUSION: These findings highlight the role of snails in immunomodulation and shed light on the possibility of antagonizing effects that might occur when the nucleoproteins of different species are mixed. Moreover, this research study might promote the literature spotting the importance of snail proteins against schistosomiasis.