Comparative effects of anthelmintics on motility in vitro of Onchocerca gutturosa, Brugia pahangi and Acanthocheilonema viteae.

The effects of standard anthelmintics on the motor activity in vitro of adult Onchocerca gutturosa, Brugia pahangi and Acanthocheilonema viteae were determined using a micromotility meter. Fresh adult males dissected from bovine tissues were the best source for observations on O. gutturosa. Parasites liber-ated by collagenase digestion showed poor viability and motility. Only segments of O. gutturosa females were obtainable by dissection and these were not able to sustain motility in vitro. Adult males and females of O. volvulus were active after collagenase digestion of human nodular tissue, but behaved so irregularly that satisfactory monitoring of their movements with the meter was not possible on a regular enough basis to permit quantitation of drug-induced changes. Inhibitory effects on motility of O. gutturosa, B. pahangi and A. viteae were produced by anthelmintics which showed macrofilaricidal effects in vivo in a laboratory rodent model, with the exception of the benzimidazoles. O. gutturosa was, however, much more sensitive than B. pahangi or A. viteae to the temporary paralyzing effects of levamisole and pyrantel. The utility of in vitro screening against O. gutturosa and B. pahangi was evaluated by determining the discriminatory capacity of the tests in detecting novel compounds with reproducible in vivo activity in the jird-B. pahangi/A. viteae model. The results suggested that this would be a valuable selective screening procedure. Although false positives were detected at the rate of 15-17% of the novel anthelmintic chemical series tested, no false negatives were allowed through the screen provided both O. gutturosa and B. pahangi were included.2=