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Published on: January 14, 2018
Studies of the growth-regulating effects of ivermectin on larval Onchocerca lienalis in vitro
Abstract:
At concentrations of 0.1-100 ng/ml ivermectin inhibited L3-L4 molting by Onchocerca lienalis in vitro. The degree of inhibition was dose-dependent with a significant effect apparent at 0.1 ng/ml and complete inhibition occurring at 100 ng/ml. The ED50 for molt inhibition was 0.19 ng/ml. Molt-inhibiting levels of the drug were not acutely toxic to the worms. In the presence of 10 ng/ml, a concentration giving 95% molt inhibition, motility at day 7 postinoculation was 71% of that seen in nontreated controls. A more pronounced effect on motility was apparent in larvae under long-term cultivation in the presence of ivermectin. Kinetic studies indicated that the majority of the larvae respond irreversibly to the drug within the first 2 hr of exposure. Twenty-four hours of exposure were required for a maximal response. The inhibitory effects of ivermectin were less pronounced if larvae were allowed to develop under normal culture conditions for 24 or more hours prior to the initiation of drug treatment.
Insights
Ivermectin effectively inhibits Onchocerca lienalis larval molting in vitro, with significant effects at low doses. This drug demonstrates dose-dependent inhibition without acute toxicity, impacting larval development and motility.
Area of Science:
- Parasitology
- Veterinary Entomology
- Pharmacology
Background:
- Onchocerca lienalis is a filarial nematode responsible for onchocerciasis.
- Understanding anthelmintic mechanisms is crucial for disease control.
- Ivermectin is a key drug used in treating filarial infections.
Purpose of the Study:
- To investigate the in vitro efficacy of ivermectin on Onchocerca lienalis larval molting.
- To determine the dose-response relationship and ED50 for molt inhibition.
- To assess the drug's effect on larval motility and toxicity.
Main Methods:
- In vitro culture of Onchocerca lienalis larvae (L3-L4 stage).
- Exposure to varying concentrations of ivermectin (0.1-100 ng/ml).
- Assessment of molt inhibition, larval motility, and toxicity over time.
Main Results:
- Ivermectin inhibited L3-L4 molting in a dose-dependent manner, with significant inhibition at 0.1 ng/ml and complete inhibition at 100 ng/ml.
- The ED50 for molt inhibition was determined to be 0.19 ng/ml.
- Molt-inhibiting concentrations were not acutely toxic; motility was reduced but not eliminated, with greater impact under long-term exposure.
Conclusions:
- Ivermectin is a potent inhibitor of Onchocerca lienalis larval molting in vitro.
- The drug's effects are dose-dependent and occur at sub-toxic levels.
- Larval development and motility are significantly impacted by ivermectin exposure.
