Protection against arthropod parasites with purinergic receptor (opr) antagonists

A screening method for selecting an antagonist for a PR of an arthropod parasite comprising:

• Arranging at least one test animal such as to expose at least one animal cell expressing one or more PRs or at least one portion of said test animal comprising one or more purine-sensitive cells for electrophysiological measurement,
• Stimulating the one or more PRs carried on the animal cell, or on the animal portion by presenting at least one PR agonist,
• Determining the response of the animal cell or of the animal portion comprising the one or more PR over a defined period during stimulation, for example by determining the action potential frequency,
• Presenting a test compound in combination with the at least one PR agonist to the one or more PR carried on the animal cell or on the animal portion,
• Determining the response of the one or more PR carried on the animal cell or on the animal portion over a defined period during presentation of the test compound together with the at least one PR agonist, for example by determining the action potential frequency,
• Comparing the response of the animal cell or of the at least one animal portion comprising the one or more PR in absence of the test compound to the response of the animal cell, or of the animal portion when presented with the test compound,
• Determining the suitability of the test compound for use as a PR antagonist based on the result of this comparison.

A screening method for determining the ability of a PR antagonist to prevent infestation of a human and/or animal host by an arthropod parasite comprising:

• Contacting at least one the cell expressing one or more PRs of at least one test animal, or at least one portion comprising one or more purine-sensitive cells of at least one test animal with a warm substrate or warm body,
• Determining the biting rate of said at least one test animal over a defined period on said warm substrate or said warm body,
• Presenting at least one test compound on said warm substrate or said warm body contacting the at least one cell or the at least one portion of the at least one test animal,
• Determining the biting rate of said at least one test animal over a defined period in presence of the at least one test compound on said warm substrate or said warm body,
• Comparing the biting rates of said at least one test animal in the presence and in the absence of the at least one test compound;
• Determining the suitability of the at least one test compound for use as a feeding inhibitor based on the result of this comparison.

A screening method for selecting an antagonist for a PR of an arthropod parasite comprising:

• Arranging a test animal or at least one portion of said test animal such as to expose at least one animal cell expressing one or more PRs or at least one portion of said test animal comprising one or more purine-sensitive cells, or arranging a cell, a tissue or an organoid of vertebrate or invertebrate origin expressing on or more PR in or onto a medium containing a fixed dose of at least one PR agonist,
• Determining the cellular activity of said animal cell, of said at least one portion of test animal, or of said cell, tissue or organoid of vertebrate of invertebrate origin, and/or determining the growth rate of said animal cell, of said at least one portion of test animal, or of said cell, tissue or organoid of vertebrate or invertebrate origin over a defined period in presence of the at least one PR agonist in the medium,
• Presenting at least one test compound in combination with the at least one PR agonist to said animal cell, to said portion of test animal, or to said cell, tissue or organoid of vertebrate or invertebrate origin,
• Determining the cellular activity of said animal cell, of said at least one portion of test animal, or of said cell, tissue or organoid of vertebrate or invertebrate origin, or determining the growth rate of said animal cell, of said portion of test animal, or of said cell, tissue or organoid of vertebrate or invertebrate origin over a defined period in presence of the at least one PR agonist and the at least one test compound in the medium,
• Comparing the cellular activity of said animal cell, of said at least one portion of test animal, or of said cell, tissue or organoid of vertebrate or invertebrate origin expressing the one or more PR, or determining the growth rate of said of said animal cell, of said at least one portion of test animal, or of said cell, tissue or organoid of vertebrate or invertebrate origin expressing the one or more PR in the presence and in the absence of the at least one test compound,
• Determining the suitability of the at least one test compound for use as a PR antagonist based on the result of this comparison.