Research Projects

Plasmodium vivax is underexplored compared to P. falciparum, despite its significant role in sustaining malaria transmission. Its unique biological adaptations, including its ability to invade immature CD71-positive reticulocytes and its preference for cryptic reservoirs like the spleen and bone marrow, complicate malaria elimination efforts. The spleen, a critical reservoir, supports reticulocyte maturation and provides a niche for parasite replication, resulting in up to 80-fold higher parasite biomass compared to peripheral blood. These adaptations, along with spleen-dependent cytoadherence facilitated by PvSDP1 and PvEVs proteins, underline the challenges in studying P. vivax biology and devising effective interventions. A persistent limitation in P. vivax research is the inability to maintain continuous in vitro cultures due to low parasitemia and poor reproducibility of invasion assays. Past efforts, including static culture systems, white blood cell depletion, and the use of cryopreserved hematopoietic stem cells, have shown limited success. The longest reported in vitro culture achieved parasitemia below 0.1% for 26 months, underscoring the need for optimized systems. Objectives: This project aims to develop an improved platform for studying P. vivax biology through the following: Enhancing CD71-positive reticulocyte yield by co-culturing K562 erythroleukemia cells with human splenic fibroblasts (HSF). Optimizing P. vivax invasion assays using enriched schizonts and co-cultured reticulocytes. Investigating the effects of cryopreserved reticulocytes and schizonts on invasion efficiency and assay reproducibility. Methodology: Commercially sourced HSFs and K562 cells will be co-cultured under optimized conditions, followed by flow cytometry to evaluate reticulocyte yield and marker expression. Parasite invasion assays will use patient-derived and cryopreserved schizonts with co-cultured reticulocytes. Advanced techniques, including Giemsa staining and magnetic purification, will assess invasion success. Statistical analyses will determine reproducibility and efficiency of the optimized culture conditions. Expected Outcomes: The study is anticipated to significantly enhance the yield of CD71-positive reticulocytes and improve P. vivax invasion efficiency. The integration of cryopreserved cells is expected to enhance assay reproducibility, enabling more consistent long-term in vitro cultures. These advancements will facilitate detailed investigations into P. vivax biology, including its unique adaptations and host interactions, contributing to the broader goal of malaria elimination. This study represents a critical step toward overcoming the challenges of P. vivax research, providing innovative tools and platforms for future studies and intervention development.