Activity of praziquantel on in vitro transformed Schistosoma mansoni sporocysts

Abstract

Praziquantel (PZQ) is effective against all the evolutive phases of (Doenhoff et al. 2002). Nevertheless, the mechanisms of action of this drug against Schistosoma mansoni are not yet precisely clarified until now (Cioli & Picca-Mattoccia 2003). It is well known that PZQ is effective against all the evolutive phases of the parasite, being more active against cercariae and adult worms (Gonnert & Andrews 1977). Previous studies in our laboratory, as well as data from the literature, demonstrated that PZQ acts on the intramolluscan phase of Schistosoma interrupting cercarial shedding (Coles 1979, Touassem & Combes 1986, Yi & Combes 1987, Coelho et al. 1988, Riley & Chappell 1990.Morphological and physiological changes in S. mansoni under the effect of PZQ, at different evolutive phases of the parasite's life cycle, have been demonstrated using as a tool fluorescent labels. Oliveira et al. (2006) demonstrated that PZQ causes damages to the tegument of adult worms, and that these lesion sites are markedly labeled by the probe Hoechst 33258 (specific for DNA and being utilized as indicator of membrane integrity). However, the same lesions are not labelled by the probe lectin of Glycine max (specific for N-acetylgalactosamine, a carbohydrate present in the parasite tegument).In studies using S. mansoni, Al-Adhami et al. ally similar to lysosomes, in schistosomula, and the absence of them in cercariae, by means of the label Lyso Tracker Red, specific for lysosomes of mammal cells (Dietl et al. 1996). In another study, Al-Adhami et al. (2005) observed the presence of large acidic organelles in immature worms (lung stage), but not in adult worms and miracidia. Carneiro-Santos et al. (2001), besides reporting the presence of lysosomes in schistosomula, verified that PZQ interferes with the formation of acidic organelles. Thus, we evaluated in this work the presence of lysosomes in in vitro transformed S. mansoni sporocysts, as well as the activity of PZQ on those acidic organelles and on the parasite's tegument, by means of fluorescent labels. MATERIALS AND METHODSIn vitro transformation of sporocysts -Infected mice with S. mansoni cercariae (LE strain) were sacrificed after 50-day-infection. Their livers were collected and kept in sterile saline 0.85%, containing 10% antibiotics penicillin/ streptomycin (Sigma Chemical Co., St. Louis, MO, US), at room temperature, for 30 min. Afterwards, the livers were homogenized and washed to obtain miracidia, using sterile materials, according to the technique described by Pellegrino and Siqueira (1968). Miracidia were gathered into conic tubes of 50 ml and maintained on ice for 30 min. The supernatant was discarded and 5 ml liquid with miracidia were kept apart. Miracidia were cultured/transformed in culture medium RPMI-1640 pH 7.4 (Sigma) supplemented with 5% (v/v) inactivate fetal bovine serum (FBS) (Gibco Limited, Paisley, Scotland, UK) and 20 µg/ml antibiotic gentamicine in B.O.D., at 26 o C, for 24 h. Cultured medium (15 ml) was stored in bottles of 25cm 2 each, with addition o...

Evidence for Specific Genotype-Dependent Immune Priming in the Lophotrochozoan <b><i>Biomphalaria glabrata</i></b> Snail

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New insight into praziquantel against various developmental stages of schistosomes

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A Novel Bacterial Pathogen of Biomphalaria glabrata: A Potential Weapon for Schistosomiasis Control?

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