title: The effects of ivermectin on the viability of Onchocerca lienalis microfilariae in vitro and on their subsequent development in the blackfly vector, Simulium ornatum.
abstract: Experiments examined the sensitivity of Onchocerca lienalis microfilariae (mf) to ivermectin in vitro using a range of parameters to measure viability. Incubation in drug (1 x 10(-4) and 5.71 x 10(-8) M) caused an immediate decrease in motility levels in a concentration dependent fashion with a continuing decline over 24 h; the inclusion of a monkey kidney cell (LLCMK2) feeder layer in the culture system partially abrogated drug effects. The use of feeder cells allowed the longer-term culture of mf; incubation in drug at low concentrations (5.71 x 10(-8) and 1 x 10(-10) M) significantly reduced motility levels during a 17 day trial. Using MTT colorimetry it was found that 10,000 untreated mf per replicate sample were required to produce a sufficient quantity of formazan to make comparisons, and that formazan formation was most rapid during the first 30 min of incubation in MTT but continued up to 3-4 h. Following incubation of mf in ivermectin (1 x 10(-4) and 5.71 x 10(-8) M) for 24 h, only the higher concentration inhibited formazan formation (51%), while motility levels were reduced by 94% and 45% respectively. Using the same drug concentrations, mf viability was assessed by measuring the uptake of [3H]2-deoxy-D-glucose; uptake was only significantly reduced (40%) by the higher concentration, while motility levels were reduced by 77% and 63% respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: CAB International Institute of Parasitology, St. Albans, Hertfordshire, UK.
authors.forename: S
authors.initials: S
authors.lastname: Townson
authors.forename: S K
authors.initials: SK
authors.lastname: Tagboto
mesh_terms: D000818:Animals; D005947:Glucose / Q000378:metabolism; D006790:Host-Parasite Interactions / Q000187:drug effects; D007303:Insect Vectors / Q000469:parasitology*; D007559:Ivermectin / Q000494:pharmacology*; D008842:Microfilariae / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D009068:Movement / Q000187:drug effects; D009854:Onchocerca / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D010084:Oxidation-Reduction; D012843:Simuliidae / Q000469:parasitology*; D013778:Tetrazolium Salts / Q000378:metabolism
chemical_list: D013778:Tetrazolium Salts; D007559:Ivermectin; D005947:Glucose