New Study Advances Research Towards Improved Vaccine Candidates for Vivax Malaria

New Study Advances Research Towards Improved Vaccine Candidates for Vivax Malaria

Researchers have conducted a groundbreaking study to evaluate growth inhibition assays for Plasmodium vivax, the most widespread human malaria affecting approximately 2.5 billion people in South America, Oceania, and Asia. The findings of this study, published in the first paper to cite OptiViVax, contribute significantly to efforts aimed at selecting improved vaccine candidates against vivax malaria.

The study focused on testing a range of conditions to assess growth inhibition assays for Plasmodium vivax, providing crucial insights into comparing results from different assays and clinical studies. Recent data indicate a growing disease burden and the increasing importance of Plasmodium vivax malaria, highlighting the urgent need for a robust assay for blood-stage Pv vaccine development.

Results from the in vitro growth inhibition assay (GIA) with transgenic P. knowlesi (Pk) parasites expressing the Pv Duffy-binding protein region II (PvDBPII) demonstrated promising correlations with in vivo protection in the first PvDBPII controlled human malaria infection (CHMI) trials. This suggests that the PkGIA could serve as an ideal selection tool for vaccine development, pending further definition of assay precision.

To determine the precision in percentage of inhibition in GIA (%GIA) and in GIA50 (antibody concentration that gave 50 %GIA), the researchers conducted ten GIAs with transgenic Pk parasites using four different anti-PvDBPII human monoclonal antibodies (mAbs) and three GIAs with eighty anti-PvDBPII human polyclonal antibodies (pAbs). Analysis revealed significant assay-to-assay variation, with standard deviations (SD) of 13.1 in the mAb and 5.94 in the pAb dataset for %GIA, along with a LogGIA50 SD of 0.299 (for mAbs).

Furthermore, the study calculated the ninety-five percent confidence interval (95 %CI) for %GIA or GIA50 in repeat assays, providing crucial error range determinations to enable appropriate comparison of PkGIA results from different assays and studies. These findings support the development of future blood-stage malaria vaccine candidates, particularly second-generation PvDBPII-based formulations.

This research represents a significant step forward in the quest for effective vaccines against vivax malaria and underscores the importance of continued efforts in this field to combat this global health threat.