Development of an In Vitro Assay and Demonstration of Plasmodium berghei Liver-Stage Inhibition by TRAP-Specific CD8+ T Cells |
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Authors: | Rhea J. Longley Karolis Bauza Katie J. Ewer Adrian V. S. Hill Alexandra J. Spencer |
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Affiliation: | The Jenner Institute, University of Oxford, Oxford, United Kingdom.; INSERM, FRANCE, |
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Abstract: | The development of an efficacious vaccine against the Plasmodium parasite remains a top priority. Previous research has demonstrated the ability of a prime-boost virally vectored sub-unit vaccination regimen, delivering the liver-stage expressed malaria antigen TRAP, to produce high levels of antigen-specific T cells. The liver-stage of malaria is the main target of T cell-mediated immunity, yet a major challenge in assessing new T cell inducing vaccines has been the lack of a suitable pre-clinical assay. We have developed a flow-cytometry based in vitro T cell killing assay using a mouse hepatoma cell line, Hepa1-6, and Plasmodium berghei GFP expressing sporozoites. Using this assay, P. berghei TRAP-specific CD8+ T cell enriched splenocytes were shown to inhibit liver-stage parasites in an effector-to-target ratio dependent manner. Further development of this assay using human hepatocytes and P. falciparum would provide a new method to pre-clinically screen vaccine candidates and to elucidate mechanisms of protection in vitro. |
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