Fig. 2.

Conjugation process did not affect the functional epitopes for TBA. The mouse (A), rabbit (B), and rhesus (C) antisera obtained from animals immunized with Pfs25H-OMPC or Pfs25H/ISA51 were compared for their TBAs relative to the ELISA titers in membrane feeding assays. Mouse and rabbit sera used in the assays were obtained 2 weeks after the second immunization. Rhesus sera used in the assay were obtained on day 611, 2 weeks after the booster dose on day 596 (see also Fig. 3 and Table 1). Antisera and sexual-stage parasites were fed to mosquitoes together with the blood meals containing parasites, and the oocyst numbers were counted as an indication of the infectivity. The negative control samples were preimmune sera from the same species. Lines are the nonlinear regression fit of the data to a simple hyperbolic equation: % inhibition = 100·[C]/(IC₅₀ + [C]), where [C] is the anti-Pfs25 ELISA units and IC₅₀ is the anti-Pfs25 ELISA units giving 50% inhibition of oocyst number. Filled circles and solid lines indicate antisera induced by Pfs25H-OMPC conjugate, and open circles and dashed lines indicate antisera induced by Pfs25H/ISA51.