On the Run
Life as a parasite is a constant race to evade host defences. For African trypanosomes (pictured) – responsible for diseases such as sleeping sickness – staying ahead means they have to keep moving. Each is a single cell with a long hair-like structure, or flagellum, anchored to the cell body and rotating to propel it through vertebrate bloodstreams, as shown here by 3D imaging. The host immune system detects threats using antibodies, molecules that recognise and bind to specific proteins on the surface of the parasite, marking it out for destruction. Rapid swimming generates a strong enough current to drag these antibodies to the base of the flagellum, where the cell can absorb them, thus allowing trypanosomes to go unnoticed. However, this swimming behaviour could ultimately be their downfall, as research into the mechanisms of trypanosome motion and its molecular underpinnings may reveal new targets for treatment.
Written by Emmanuelle Briolat