Drug discovery starts by screening large numbers (tens or hundreds of thousands) of chemical substances (compounds) to find a starting point from which to develop a new medicine. The parasite biologists may have found a process in the parasite which is essential for the parasite to live. This gives us a ‘target’, usually a protein, for our drugs and so we call the screen a ‘target’ screen. If we decide to look for any compound that kills the parasites growing in our laboratory cultures then it is called a ‘phenotypic’ screen’. (A ‘phenotype’ is the term to describe some aspect of the outward appearance of an organism, this includes being alive or dead.) We then need the Mode of Action team to discover why the compound kills the parasites. This may lead us to a single process/protein in the parasite and so we can then carry out a target screen.
We call compounds that either affect the function of the ‘target’ or kill the parasite within the screen ‘hits’. We confirm (validate) the hits by running them through more experiments. Knowledge from the parasite biology teams’ research helps to design experiments (assays) which allow us to understand how the ‘hit’ interferes with the parasite. The results of these assays allows scientists to rank hits based on how good a starting point they are for the development of a new medicine.
Follow the links below to find out more about how we find and verify the ‘hits’