Whole-organ isolation approach as a basis for tissue-specific analyses in Schistosoma mansoni

As a neglected disease, schistosomiasis is still an enormous problem in the tropics and subtropics. Since the 1980s, Praziquantel (PZQ) has been the drug of choice but can be anticipated to lose efficacy in the future due to emerging resistance. Alternative drugs or efficient vaccines are still lacking, strengthening the need for the discovery of novel strategies and targets for combating schistosomiasis. One avenue is to understand the unique reproductive biology of this trematode in more detail. Sexual maturation of the adult female depends on a constant pairing with the male. This is a crucial prerequisite for the differentiation of the female reproductive organs such as the vitellarium and ovary, and consequently for the production of mature eggs. These are needed for life-cycle maintenance, but they also cause pathogenesis. With respect to adult males, the production of mature sperm is essential for fertilisation and life-cycle progression. In our study we present a convenient and inexpensive method to isolate reproductive tissues from adult schistosomes in high amounts and purity, representing a source for gonad-specific RNA and protein, which will serve for future sub-transcriptome and -proteome studies helping to characterise genes, or to unravel differentiation programs in schistosome gonads. Beyond that, isolated organs may be useful for approaches to establish cell cultures, desperately needed in the post-genomic era

Development of emodepside as a possible adulticidal treatment for human onchocerciasis-The fruit of a successful industrial-academic collaboration

Current mass drug administration (MDA) programs for the treatment of human river blindness (onchocerciasis) caused by the filarial worm Onchocerca volvulus rely on ivermectin, an anthelmintic originally developed for animal health. These treatments are primarily directed against migrating microfilariae and also suppress fecundity for several months, but fail to eliminate adult O. volvulus. Therefore, elimination programs need time frames of decades, well exceeding the life span of adult worms. The situation is worsened by decreased ivermectin efficacy after long-term therapy. To improve treatment options against onchocerciasis, a drug development candidate should ideally kill or irreversibly sterilize adult worms. Emodepside is a broad-spectrum anthelmintic used for the treatment of parasitic nematodes in cats and dogs (Profender and Procox). Our current knowledge of the pharmacology of emodepside is the result of more than 2 decades of intensive collaborative research between academia and the pharmaceutical industry. Emodepside has a novel mode of action with a broad spectrum of activity, including against extraintestinal nematode stages such as migrating larvae or macrofilariae. Therefore, emodepside is considered to be among the most promising candidates for evaluation as an adulticide treatment against onchocerciasis. Consequently, in 2014, Bayer and the Drugs for Neglected Diseases initiative (DNDi) started a collaboration to develop emodepside for the treatment of patients suffering from the disease. Macrofilaricidal activity has been demonstrated in various models, including Onchocerca ochengi in cattle, the parasite most closely related to O. volvulus. Emodepside has now successfully passed Phase I clinical trials, and a Phase II study is planned. This Bayer–DNDi partnership is an outstanding example of “One World Health,” in which experience gained in veterinary science and drug development is translated to human health and leads to improved tools to combat neglected tropical diseases (NTDs) and shorten development pathways and timelines in an otherwise neglected area

Emodepside targets SLO-1 channels of Onchocerca ochengi and induces broad anthelmintic effects in a bovine model of onchocerciasis

Onchocerciasis (river blindness), caused by the filarial worm Onchocerca volvulus, is a neglected tropical disease mostly affecting sub-Saharan Africa and is responsible for >1.3 million years lived with disability. Current control relies almost entirely on ivermectin, which suppresses symptoms caused by the first-stage larvae (microfilariae) but does not kill the long-lived adults. Here, we evaluated emodepside, a semi-synthetic cyclooctadepsipeptide registered for deworming applications in companion animals, for activity against adult filariae (i.e., as a macrofilaricide). We demonstrate the equivalence of emodepside activity on SLO-1 potassium channels in Onchocerca volvulus and Onchocerca ochengi, its sister species from cattle. Evaluation of emodepside in cattle as single or 7-day treatments at two doses (0.15 and 0.75 mg/kg) revealed rapid activity against microfilariae, prolonged suppression of female worm fecundity, and macrofilaricidal effects by 18 months post treatment. The drug was well tolerated, causing only transiently increased blood glucose. Female adult worms were mostly paralyzed; however, some retained metabolic activity even in the multiple high-dose group. These data support ongoing clinical development of emodepside to treat river blindness

Protein patterns of <i>S. mansoni</i> organs/tissues and adults.

<p>1.2 µg total protein from male (Mars symbol), female (Venus symbol), testes (Te), ovaries (Ov), and male tegument (T) were separated by 13% SDS-PAGE and visualised by silver staining. Marker (M) = PageRuler Plus Prestained Protein Ladder (Fermentas).</p

Summary of gene-specific expression patterns.

<p>* = current study, <b>+</b> = detected, <b>−</b> = not detected, <b>nd</b> = not determined.</p

Gonad protein-specific immunoblots.

<p>15 µg of total protein per lane isolated from adult worms (Mars and Venus symbol), testes (Te), ovaries (Ov), and tegumental proteins of both genders (T) were analysed by immunoblotting employing immune sera directed against SmSPRM1hc (Permease 1 heavy chain), SmHSP70 (Heat shock protein 70), SmAQP (Aquaporin), and SmFKBP12 (FK506-binding protein); for references see <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002336#pntd-0002336-t001" target="_blank">Table 1</a>.</p

Schematic illustration and bright-field microscopy (BF) of gonad tissues following tegument solubilisation and protease treatment.

<p><b>A)</b> Crude preparation of intact testes (TE) together with a part of an incompletely digested male worm body (MB) and different types of cells (CE) (left) and an mature ovary (Om) surrounded mainly by S4-vitelline cells (VC) from the vitellarium (right); immature ovary (Oi) and ootype (OT) with vitelloduct (VD) and oviduct (OD) isolated from a unisexual female; the ootype was contrasted by brief staining with Ponceau S; asterisk: “hymen”-like morphological structure typical for ootypes of unisexual females <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002336#pntd.0002336-Beckmann1" target="_blank">[18]</a>, <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002336#pntd.0002336-Beckmann2" target="_blank">[108] </a><b>B)</b> Mechanical transfer by pipetting led to the enrichment of pure testes (TE), mature ovaries (Om) after collecting and concentrating. TL (testes lobe), Op (ovary - posterior part containing mature primary oocytes in the case of mature ovaries), Oa (ovary - anterior part containing immature, stem cell-like oogonia); vitellarium (VI) with vitelline lobes (VL); dashed arrow = continued from <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002336#pntd-0002336-g001" target="_blank">Figure 1</a>.</p

Target genes and RT-PCR primers.

<p>Target genes and RT-PCR primers.</p