The Wiggleometer: Measuring Larval Movement in a 96 Well Format

Abstract

ABSTRACT here has been relatively little progress in the area of highthroughput screening for antiparasitic animal health tar-gets, which involve whole organisms such as Haemonchus contortus and Caenorhabditis elegans. Mostassays involve identifying compounds that can paralyze and/or killthe organism. A major impediment has been the lack of instrumen-tation suitable for automating the read-out of these assays. We havedeveloped an automated reader that makes analysis of antiparasiticanimal health assays possible. This reader uses computer visiontechniques to determine whether or not there is larval motion ineach well. The system has been validated by measuring the dose-response relationships for several nematocidal agents and by exam-ining 1040 wells of H. contortus, with a 94.6%/94% concordancerate with a human reader with less than a 0.3% false negative rate. INTRODUCTION High throughput screening (HTS), has gained widespreadacceptance as an automation tool for biological assays in the phar-maceutical industry. A requirement for employing this methodol-ogy is a digitally readable endpoint. There has been substantialprogress in fields such as ion-channels, receptor-ligand, and enzy-matic assays where instrumentation can readily read colorimetric,fluorimetric or radioligand results. However, there has been lessprogress in fields such as parasitology, where the endpoint is oftenthe lack of bioactivity, such as loss of motion, which is not cur-rently determined by instrumentation.Anthelmintic assays generally screen for compounds thatinterfere with larval development or that paralyze and/or killthe study organism. The two types of assays used are develop-mental assays, where eggs or staged larvae are seeded and larvaldevelopment is scored some days later, or shorter term ‘kill’assays where compounds are tested on larvae or adults, and killis assessed shortly thereafter. Both types of assays, however, relyon the manual observation of lack of movement or develop-ment of the organism. In this paper, we describe theWiggleometer, an automated methodology for a reproduciblemeasurement of these endpoints, has been implementedrepro-ducibly measuring these endpoints in a 96 well format, suitablefor HTS, is described.