The investigation of protective concomitant immunity in murine schistosomiasis mansoni

The present study was conducted mainly to establish a new concomitant immunity model to Schistosoma mansoni in mice and assess its effects on the resistance of mice to a challenge infection with a possibility of using as a diagnostic marker. Three groups (A, B and C) of BALB/c mice were infected with a single dose of S. mansoni cercariae obtained from infected Biomphalaria glabrata snail. The group A mice were used as infected control group. The group B mice were intraperitoneally injected with allylthiourea (ATU) 22 days post-primary infection then they were challenged 3 weeks post-ATU treatment. The group C mice were challenged with the same number of cercariae 6 weeks post-primary infection. Perfusion of all mice was done 9 weeks after infection in order to obtain worm burdens. The livers of all mice were obtained for parasitological and pathological assessments. Our results showed that the group B mice had a 29.11% worm reduction rate, 25.37% liver egg reduction rate, and 37.48% granuloma size reduction rate compared to their respective controls. While the group C mice showed superior results and had a 54.66% worm reduction rate, 41.45% liver egg reduction rate, and 51.76% granuloma size reduction rate. It was concluded that these results described novel imaging methods that permit visualization of live schistosomes within their living hosts and may have important implications not only for epidemiological and diagnostic investigations, but also in designing control programs for schistosomiasis including anti-schistosome vaccine.