Sites and mechanisms of schistosome elimination

Specific humoral response of hosts with variable schistosomiasis susceptibility

“…The skin‐ and lung‐stage schistosomulum lifecycle stages are believed to be the most vulnerable to elimination by the host's immune system 9 , 15 , 16 thereby making larval‐stage‐specific antigens attractive vaccine targets. Our previous work 26 has shown that ASC probes from the skin‐ and lung‐draining LNs of the rat were induced by the passage of migrating schistosome larval stages.…”

“…62 The mouse sera, on the other hand, had low protein microarray reactivity and recognized fewer features reflecting the increased susceptibility and weaker immune response in this animal model. 8,9,11,21 The skin-and lung-stage schistosomulum lifecycle stages are believed to be the most vulnerable to elimination by the host's immune system 9,15,16 thereby making larval-stage-specific antigens attractive vaccine targets. Our previous work 26 has shown that ASC probes from the skin-and lung-draining LNs of the rat were induced by the passage of migrating schistosome larval stages.…”

“…8,9,11,14 The migration path of the schistosome parasite from skin to lung is critical for both immune priming and parasite killing. 9,15,16 Following infection with S. japonicum or S. mansoni cercariae the rat eliminates the parasites over the course of a few weeks, in the lungs and the liver; with the majority of the schistosomules never progressing past the lung. [16][17][18] The few worms found in the liver are stunted, produce few fertile eggs and these worms are eventually eliminated by a self-cure phenomenon.…”

“…9,15,16 Following infection with S. japonicum or S. mansoni cercariae the rat eliminates the parasites over the course of a few weeks, in the lungs and the liver; with the majority of the schistosomules never progressing past the lung. [16][17][18] The few worms found in the liver are stunted, produce few fertile eggs and these worms are eventually eliminated by a self-cure phenomenon. 7,9,14,18 Upon reinfection, the challenge parasites are rapidly eliminated at or before the lung stage.…”

Why the radiation-attenuated cercarial immunization studies failed to guide the road for an effective schistosomiasis vaccine: A review

“…Thus, in inbred CBA/Ca mice exposed to 400 S. mansoni cercariae attenuated with 20 krad of 60 Co irradiation, challenge parasites were found to be killed within the first 4 days after challenge, i.e., at the skin stage [12,49–51] . Conversely, in mice immunized by exposure to S. mansoni RA cercariae (50 krad, 2 krad/min of 60 Co radiation), mincing and incubation [52] as well as autoradiographic studies of challenge infection with approximately 200 L-( 75 Se) selenomethionine-labeled but otherwise normal cercariae indicated that worm elimination occurs after the skin stage, essentially in the lungs [12,33,34,39,53–56] . Challenge schistosomula were found to reach the liver in reduced numbers or are killed or cleared extravascularly in the liver in greater number in immunized mice, suggesting that the liver is a site of challenge worm attrition in mice immunized with RA larvae [53] or previously infected mice as well [57] .…”