Fig. 4

Reactivity of vaccine-induced antisera to native parasite antigen. a Western blot analysis under reducing conditions of gametocyte (GC) and ookinete (Ook) parasite lysates using anti-PSOP26 + PSOP26 sera (left) and anti-PSOP25-PSOP26 sera. PSOP25 and PSOP26 protein bands are indicated with arrows. Equal loading was estimated using anti-rHsp70 sera. b Indirect immunofluorescence analysis using the bivalent immune sera. Parasites of different developmental stages were fixed, permeabilized with 0.1% Triton X-100, and stained with antisera against PSOP25 + PSOP26 (left) and PSOP25-PSOP26 (right) (1:200) as the primary antibodies (green). The parasites were also co-labeled with antibodies against the markers for different stages (red), including α-tubulin (α) for male gametocytes/gametes, P47 for female gametocytes, Pbs21 for zygotes and ookinetes, and SET for the nucleus of gametocytes. Alexa Fluor 488-conjugated goat anti-mouse IgG antibodies and Alexa Fluor 555-conjugated goat anti-rabbit IgG antibodies were used as the secondary antibodies. The sera from mice receiving Trx-His recombinant proteins were included as negative controls. Antibody binding was detected by Alexa Fluor 555-conjugated goat anti-rabbit IgG (red) (lane 1), and Alexa Fluor 488-conjugated goat anti-mouse IgG (green) (lane 2). DNA was stained with DAPI (blue) (lane 3). DIC images (lane 4), and merged view (lane 5) are shown. Scale bar, 5 µm