FIG 3.

Immunization with Pyfabb/f⁻ induces antibodies that are sufficient to protect mice against sporozoite challenge by mosquito bite. BALB/c or C57BL/6 mice (n = 7 to 8 mice/group) were immunized with 3 doses of 50,000 Pyfabb/f⁻ sporozoites or mock immunized with uninfected salivary gland debris. At 24 days after the last dose, mice were treated with antibodies that deplete CD8 and CD4 T cells before challenge by the bite of 15 mosquitos infected with PyGFP-luc sporozoites. Control mice received equal amounts of isotype control IgG2b. Liver-stage burden was quantified by bioluminescent imaging 42 to 44 h after challenge. (A) Representative images of in vivo bioluminescence imaging. The scale indicates radiance expressed as p/s/cm²/sr. (B) Quantification of luciferase signal (measured as total flux per second). The horizontal bars correspond to the median, and the error bars show the interquartile range. Significant differences between groups were calculated using the Mann-Whitney test; * = P < 0.01; *** = P < 0.001; n.s. = nonsignificant. (C) Patency graphs of BALB/c (left panel) and C57BL/6 (right panel) mice. Parasitemia was determined by a Giemsa-stained thin blood smear procedure daily from day 3 to day 17 after challenge.