Chemotherapy for onchocerciasis: results of in vitro experiments with promising new compounds.

An improved short-term in vitro culture system was used for the routine screening of hundreds of promising new compounds with the target organism, the filarial nematode Onchocerca volvulus. The most active leads were identified among the pyrimidinylguanidines, amidine derivatives, the imidazolinylhydrazones, thiosemicarbazone derivatives and thiadiazole derivatives. Single compounds of these leads demonstrated strong macrofilaricidal efficacy in minimum effective dose trials down to 0.

Demonstration of immunoglobulin G antibodies against Onchocerca volvulus excretory-secretory antigens in different forms and stages of onchocerciasis.

The excretory-secretory (E-S) products of helminths are considered to comprise immunogenic molecules of high diagnostic value. In the present study, the serodiagnostic potential of the E-S products released in vitro by cultured female Onchocerca volvulus was investigated by enzyme-linked immunosorbent assay (ELISA) and Western blotting using 190 serum samples from persons infected with O. volvulus and unexposed persons.

The anterior central nervous system of male Onchocerca volvulus (Nematoda:Filarioidea) as a target for chemotherapy: results of an electron microscopy study.

An electron microscopy study was performed to evaluate the feasibility of the use of the anterior nerve ring of male Onchocerca volvulus for the assessment of early drug effects. Worms were exposed to new and known compounds at reasonable concentrations of 1 microM and less for 6, 12, 18, and 36 h in an established in vitro system. The anterior end of the filariae up to a length of 1 mm was examined and the morphological findings were compared with motility and reduction of a tetrazolium sat to formazan by live but not dead worms.

The ultrastructure of the anterior end of male Onchocerca volvulus: papillae, amphids, nerve ring and first indication of an excretory system in the adult filarial worm.

A detailed morphological investigation of the anterior sensory organs, the nerve ring and a glomerulus-like structure in male Onchocerca volvulus was performed by means of electron microscopy. The 8 head papillae are arranged in the common 4 + 4 pattern of most filarial worms in circles around the mouth opening. The amphidial openings are found between the circles of inner and outer papillae on both sides of the mouth.

Ultrastructure study of the excretory system and the genital primordium of the infective stage of Onchocerca volvulus (Nematoda:Filarioidea).

The electron microscopic investigation of the anterior part of the infective third-stage juvenile of Onchocerca volvulus provides first insights into the structure of the excretory system of this developmental stage of the parasite. The most anterior part of this system consists of a cell process of the syncytial excretory cells. At this height the excretory cells enclose the cuticle-lined excretory channel.