Immunological and protection studies.

<p>(<b>A</b>) Indirect immunofluorescence assay using group A <i>Aotus</i> monkey's sera (obtained 20 days after the 3<sup>rd</sup> immunization with HABP <b>24112 and</b> 1 day prior to challenge), displaying a merozoite membrane reactivity pattern characteristic of MSP-2's localization in late schizonts. (<b>B</b>) Western blot analysis of schizont-lysate <i>P. falciparum</i> proteins reacting with sera from Group A monkeys (monkeys 192, 149, 250, 259, 239 and 277), obtained 20 days after the 3rd immunization and the day previous to the challenge, tested at 1∶200 dilution. Sera are recognizing <i>P. falciparum</i> proteins of 69 kDa and cleavage fragments of 63, 54, 51 and 48 kDa. (<b>C</b>) Parasitemias developed in immunized <i>Aotus</i> monkeys from groups A–C and the control group D. The percentage of parasitized red blood cells was evaluated daily by Acridine Orange staining read on a fluorescence microscope, starting on day 4 post-challenge and until day 15. In those <b>fully protected </b><i>Aotus</i> monkeys the complete slide was read with ∼1.000.000 RBCs being screened. Each monkey in each group is represented by a different symbol.</p>