On the topic
Malaria is a health problem that still threatens millions of lives in the Tropics. Among the five Plasmodium species causing this disease, Plasmodium vivax is the second most prevalent worldwide and the most predominant in the Americas and Asia-Pacific regions. Due to its unique biology, P. vivax forms hypnozoites that can remain dormant for years and whose re-activation can cause relapsing blood-stage infections. P. vivax also have a shorter life cycle within the Anopheles female mosquitoes, which grants this malaria species to be less susceptible to common vector control measures. Therefore, vaccination is of particular interest to combat this parasite. Patients infected with P. vivax can develop protective immunity against clinical infections. This protective immunity is not yet fully understood, but antibody responses against different P. vivax antigens are thought to be essential to achieve such protective effect.
The discussed paper described a research effort to identify candidate P. vivax antigens for functional characterization. With this purpose, the study investigated the association between IgG antibody responses against 38 P. vivax recombinant antigens and the prospective risk of P. vivax malaria in a longitudinal cohort of young Papua New Guinean (PNG) children whose history of P. vivax infections was well characterized. A total of 264 children with age between 1 and 3 years old were enrolled in this study and followed up for 16 months with an active monitoring every two weeks. Finally, the study applied a novel methodology of simulated annealing algorithm to investigate the potential protective efficacy (PPE) of antibodies to multiple antigen-combinations and the antibody thresholds associated with protection.
The analysis suggested that high antibody levels to multiple antigens, including several novel proteins were strongly associated with malaria protection against P. vivax independently of individual differences in infection history, age, and transmission season. Additionally, combined antibody responses against five antigens had a PPE above 90%. Among these combinations, antibody responses against EBP, DBPII, RBP1a, CyRPA, and PVX_081550 were most frequently identified, with several of them requiring very low antibody levels to show a protective effect.