Mechanisms mediating antigenic variation in Trypanosoma brucei

Antigenic variation in Trypanosoma brucei is a highly sophisticated surviva l strategy involving switching between the transcription of one of an estim ated thousand variant surface glycoprotein (VSG) genes. Switching involves either transcriptional control, resulting in switching between different VS G expression sites, or DNA rearrangement events slotting previously, inacti ve VSG genes into an active VSG expression site. In recent years, considera ble progress has been made in techniques allowing us to genetically, modify , infective bloodstream form trypanosomes. This is allowing us to reenginee r VSG expression sites, and look at the effect on the mechanisms subsequent ly used for antigenic variation. We can now begin a dissection of a highly, complicated survival strategy, mediated by, many different mechanisms oper ating simultaneously.