Resistance of band 3–GPA–deficient mice to malaria infection. (A) P yoelii 17XL infection to wild-type (band 3^+/+), heterozygous (^+/−), and band 3–GPA–deficient (^−/−) mice in vivo as described in “Materials and methods.” (B) P yoelii challenge in mice deficient of protein 4.2. (C) Human and mouse RBCs were challenged with P falciparum in vitro and the ring-stage parasites were counted. No invasion of P falciparum was detected in band 3–GPA–deficient (^−/−) RBCs during the first cycle of invasion in vitro. (D) Representative images of RBCs from infected wild-type (^+/+) and band 3–GPA–deficient (^−/−) mice (from panel C) indicate the relative intact morphology of mutant RBCs under the in vitro invasion conditions. Wright-Giemsa was used for staining and images were observed at ×100 magnification. It is noteworthy that the putative regions of P falciparum MSP1 that bind to band 3 (MSP1₁₉) and GPA (MSP1₁₂) show 48.5% and 43.8% sequence identity, respectively, with their counterparts in P yoelii MSP1.