FIG 4.

P. yoelii lisp2⁻ plasmei2⁻ GAP immunization of SW mice elicits humoral responses to multiple life cycle stages. (A to E) IFA was used to determine IgG antibody activity against the parasite from GAP-immunized mice. Sera from five pooled mice were diluted 1:200 for IFA, and bound antibody was detected with a fluorescent secondary antibody. (A) Sera from GAP-immunized mice (IgG, top left, in red) but not sera from naive mice (IgG, top right) recognize the sporozoite surface. Differential interference contrast images of the sporozoites are shown in the bottom images. (B-to D) Liver stage IFAs using GAP-immunized sera (shown in red) show cross-reactivity with CSP (shown in green) at 24 h of development (B) and internal reactivity at 34 (C) and 44 h (D) of development. The parasite was visualized with antibody to BiP (shown in green). (E) GAP-immunized sera recognizes the blood stage merozoite interior, and the merozoite surface was visualized with antibody to MSP1 (green). In panels B to E, DNA is shown in blue. Scale bars in panels A and E represent 5 μm, and those in panels B to D represent 10 μm.