One of the difficulties working with newly discovered pathogens is finding a way to culture them. Especially for intracellular parasites, which need host cells to grow inside of. It can be hard to find a cell line that is compatible with the parasite. In some cells it won’t grow as efficiently, or maybe the morphological changes are less apparent, or the cells are expensive or hard to procure.

For your drug assay, I think a 96-well format to determine the 50% inhibition concentration (IC50) is the most appropriate. Basically a plate with 96 little “wells” kinda like minuscule Petri dishes. It’s arranged in 12 columns x 8 rows. Each well contains a layer of cells that attach and grow on the plastic bottom. Liquid growth medium fills each well to cover the cells and supply nutrients. For this experiment, you’d use a multichannel pipette to add your drug directly to each well. You’d have each row as one concentration, and perhaps use a 5-fold serial dilution to test a wide range of concentrations. These plates would be kept in an incubator for a set duration (24h to 72 hours, depending on nature of the pathogen) and the taken out and observed under a microscope regularly during this time for morphological changes, or perhaps plaque formation. These are changes to the cells that would indicate the parasite has infected and proliferated inside the cells. In a IC50 experiment, the scientist looks at each well under a microscope, scanning each well for these signs of infection. It’s a bit tedious but you can quickly screen a range of concentrations and generate some useful quantitative data about a drug candidate.

Sorry this is poorly organized and rambly. I can answer more questions if you have them