P falciparum EBA-175 preferably binds type O RBCs. RBCs were allowed to interact with COS7 cells expressing pfEBA-175 along with GFP.²¹  Unbound cells were washed, and the percentage of rosettes per GFP-expressing cell was determined for each sample; results were normalized such that rosettes/GFP for type A RBCs equal to 1. Whereas type A and B RBCs formed the same number of rosettes/GFP-positive cell, type O RBCs formed 1.65× more rosettes/GFP (n = 6, P < .001). A-Zyme–treated and B-Zyme–treated RBCs formed the same number of rosettes/GFP-positive cell as type O RBCs (n = 3, P = .4). Statistical significance was determined by an unpaired, 2-tailed t test. Error bars indicate SD.