Attenuation of<i>Schistosoma mansoni</i>cercariae with a molluscicide derived from<i>Millettia thonningii</i>

Parasitology - Tập 109 Số 5 - Trang 559-563 - 1994
S. Perrett1, P. J. Whitfield2, Anna Bartlett3, Lisa Sanderson2
1Division of Life Sciences, King's College, London.
2Infection and Immunity Research Group, Division of Life Sciences, King's College London, London W8 7AH
3North East Surrey College of Technology, Reigate Road, Ewell, Surrey KT13 3DS

Tóm tắt

A chloroform extract of molluscicidal plant secondary compounds from the seeds of a West African legumeMillettia thonningiiwas used to attenuate cercariae ofSchistosoma mansoniprior to infection of NMRI female mice. Exposure of cercariae to 0·3, 0·6, 1·3, 2·5, 10 or 20 mg/l concentrations of extract for 30 mm, immediately before standardized infection, was associated with a concentration-dependent decline in worm establishment at 55 days post-infection. The mean numbers of adult worms established declined from about 17 worms/mouse with control cercariae and those exposed to 0·3 mg/lMillettiato 0·1 worms/mouse after 10 mg/l pre-treatment. Mice exposed to cercariae after 20 mg/l pre-treatment had no adult worms at 55 days post-infection. The activities of cercariae 30 mm after exposure toMillettiaextract at concentrations up to 2·5 mg/l were similar to those of control larvae: none was immobile. Exposure to higher concentrations ofMillettiaprogressively reduced swimming activity and increased the proportion of immobile cercariae. After pretreatment with 20 mg/lMillettiathe majority of larvae were immobile. Levels of anti-parasite antibodies (estimated by ELISA assay using an adult worm-based antigen preparation) rose between 21 and 55 days p.i. with control cercariae and those pre-treated with 2·5 mg/lMillettia. After 5 mg/l pre-treatment, cercariae induced a reduced antibody rise, while mice exposed to cercariae after 10 mg/l pre-treatment showed no rise in anti-parasite antibody levels. These results are discussed in the context of protocols which could possibly useMillettia-attenuated cercariae to induce useful levels of protection in mice towards further cercarial challenge.

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Tài liệu tham khảo

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Parasitology

Tập 109 Số 5

559-563

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