ART4 and infection: This is in contrast to the EP/GPEET null mutant generated in bloodstream forms, which makes the transition from a full VSG coat to no glycoprotein coat when the parasite differentiates to the procyclic form [20] or to the Nour 6C mutant [21], which first becomes negative for procyclins when GPEET is repressed a few days post infection in the fly midgut [16].