(A, B) Immunoelectron microscopic analysis of B. microti LabS1–infected mouse erythrocytes. Ultrathin sections of high-pressure frozen and Durcupan resin–embedded infected erythrocytes were immunolabeled with anti-BmGPI12 polyclonal antibodies (amino acid 1–302). Scale bars: 500 nm (A, B). (C) Schematic diagram showing the steps in the UC of plasma samples collected from B. microti–infected mice. (D) Immunoblot analyses using preimmune (PI) serum, and anti-BmGPI12 or anti–TER-119 antibodies on either intact plasma (PL) collected from mice infected with B. microti LabS1 strain or on two fractions (supernatant: Us and pellet: Up) of plasma after UC at 120,000g. (E, F) Immunoelectron microscopic analysis of the plasma membrane fraction (Up) from mice infected with B. microti LabS1 using anti-BmGPI12 antibodies coupled to 10-nm gold particles. Scale bars: 200 nm (E), 100 nm (F). P, parasite; RBCC, red blood cell cytoplasm; RBCM, red blood cell membrane.