Partial resistance to <i>Schistosoma mansoni</i> in mice inoculated with cercarial bodies

Abstract

One group of mice was inoculated with Schistosorna mansoni cercarial bodies. Another group was inoculated with cercarial tails and a third group inoculated with cercarial bodies plus tails in an attempt to determine if schistosome cercarial parts elicit differing immune responses. The mice were then challenged with 100 viable cercariae as were control mice. At six weeks after infection, adult schistosomes were recovered by perfusion. The average worm burden for mice inoculated with cercarial bodies was 9.07 compared to 21.00 for mice inoculated with cercarial tails, 21.90 for mice inoculated with bodies plus tails, and 23.30 for control mice. The number of adults recovered from mice inoculated with cercarial bodies was significantly less than from mice inoculated with cercarial tails, or bodies plus tails, and control mice. Two serodiagnosic tests, Cercarien-hullen Reaction (CHR) and immunodiffusion, were conducted with sera from experimental and control mice. CHR tests were positive for all experimental mice with strongest reactions occurring with infected mice and with mice inoculated with cercarial bodies. Precipitating antibodies against whole cercarial antigen were shown using anti-body, anti-body-plus-tail, and infected mouse serum. No precipitating antibodies were shown against whole cercarial antigen using anti-tail mouse serum. The possibility of a cercarial body-tail interaction resulting in stimulation to develop or protection for the developing schistosomulum is indicated.