Fig 1.

Recombinant AnAPN1, produced in E. coli, exhibits intrinsic antigenicity in mice and is capable of eliciting functional malaria transmission-blocking antibodies in the absence of adjuvant. (a and b) A single-prime and three-boost immunization dose regimen (2 μg/dose at 2-week intervals) produces a robust antigen-specific antibody response in mice compared to that seen in controls (mice receiving only incomplete Freund's adjuvant). Sera have been pooled from 4 or 5 mice/cohort. (c and d) A single prime and -boost dose at day 28 (2 μg/dose) produce an antibody response for week 8 postimmunization sera comparable to that seen in panel b. Sera were pooled from 4 or 5 mice/cohort. (e and f) Direct feeding assay (DFA) results demonstrated that mice receiving AnAPN1 (2 μg/dose) in the absence of adjuvant elicited transmission-blocking antibodies against Plasmodium berghei in Anopheles stephensi mosquitoes. Control group values are shown as open circles (corresponding to panel c). Treatment group values are shown as filled circles (corresponding to panel d). Horizontal bars indicate median oocyst numbers per mosquito midgut. The lower table highlights the statistical significance of the Pr value of 0.031430 as determined by the GEE model. Data are representative of two independent biological replicate cohort immunization studies.