A new technique of in vitro assay of antifilarials using different life-forms of Acanthocheilonema viteae

An approach has been made to develop an in vitro screening system to evaluate antifilarial efficacy of compounds and an effort has been made to establish correlation between in vivo and in vitro screening technique. The in vitro experiments were conducted simultaneously using three life-forms (adult, microfilaria and infective larva) of Acanthocheilonema viteae using five antifilarial agents representing four chemical groups. All the selected antifilarials were known to be active against one or more life-stages of human lymphatic or animal filariids. Diethylcarbamazine and Centperazine showed 100% microfilaricidal and infective larvicidal actions at concentrations of 0.5 and 0.25 mg/ml and 0.5 and 0.0313 mg/ml respectively with no effect on adult worms even at 1 mg/ml. Levamisole was effective against all the three life-stages killing 100% adult worms at 1 mg/ml, infective larvae at 0.0625 mg/ml and microfilariae at 0.0125 mg/ml, while mebendazole exhibited activity only against adult worms (100% at 0.5 mg/ml). Ivermectin killed adult females and microfilariae at 0.063 and 0.5 mg/ml respectively but did not affect infective larvae even up to 1 mg/ml concentration. The study indicated that in vitro screening system can be used for primary screening of potential antifilarial agents provided three life-forms of A. viteae are used simultaneously to avoid false negative results. It would however be more appropriate if a few compounds of a particular chemical class are initially assessed both in vivo and in vitro for validity of subsequent test results in vitro.