Immunization induces antibody responses to proteins associated with the Py RMP fraction. Animals were immunized three times with the Py RMP preparation and sera were collected. Proteins associated with the membrane of uninfected RBCs (lane 1) or P. yoelii 17X infected RBCs (lane 2) were separated by SDS-PAGE, immunoblotted and probed with a pool of Py RMP antisera. Normal mouse sera (NMS) served as a negative control. Molecular weights in kiloDaltons (kDa) are indicated.