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Discriminating Protective from Nonprotective Plasmodium-Specific CD8+ T Cell Responses
Journal article   Peer reviewed

Discriminating Protective from Nonprotective Plasmodium-Specific CD8+ T Cell Responses

Katherine L Doll, Lecia L Pewe, Samarchith P Kurup and John T Harty
The Journal of immunology (1950), Vol.196(10), pp.4253-4262
05/15/2016
DOI: 10.4049/jimmunol.1600155
PMCID: PMC4868661
PMID: 27084099

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Abstract

Despite decades of research, malaria remains a global health crisis. Current subunit vaccine approaches do not provide efficient long-term, sterilizing immunity against Plasmodium infections in humans. Conversely, whole parasite vaccinations with their larger array of target Ags have conferred long-lasting sterilizing protection to humans. Similar studies in rodent models of malaria reveal that CD8(+) T cells play a critical role in liver-stage immunity after whole parasite vaccination. However, it is unknown whether all CD8(+) T cell specificities elicited by whole parasite vaccination contribute to protection, an issue of great relevance for enhanced subunit vaccination. In this article, we show that robust CD8(+) T cell responses of similar phenotype are mounted after prime-boost immunization against Plasmodium berghei glideosome-associated protein 5041-48-, sporozoite-specific protein 20318-325-, thrombospondin-related adhesion protein (TRAP) 130-138-, or circumsporozoite protein (CSP) 252-260-derived epitopes in mice, but only CSP252-260- and TRAP130-138-specific CD8(+) T cells provide sterilizing immunity and reduce liver parasite burden after sporozoite challenge. Further, CD8(+) T cells specific to sporozoite surface-expressed CSP and TRAP proteins, but not intracellular glideosome-associated protein 50 and sporozoite-specific protein 20, efficiently recognize sporozoite-infected hepatocytes in vitro. These results suggest that: 1) protection-relevant antigenic targets, regardless of their immunogenic potential, must be efficiently presented by infected hepatocytes for CD8(+) T cells to eliminate liver-stage Plasmodium infection; and 2) proteins expressed on the surface of sporozoites may be good target Ags for protective CD8(+) T cells.
Plasmodium berghei - immunology Antigens, Protozoan - immunology Malaria - immunology Mice, Inbred C57BL Cells, Cultured Vaccines, Subunit - immunology Hepatocytes - immunology Sporozoites - immunology Hepatocytes - parasitology Malaria - prevention & control Animals Malaria Vaccines - immunology Female Immunization Schedule Immunologic Memory Mice Mice, Inbred BALB C Epitopes, T-Lymphocyte - immunology Liver - parasitology CD8-Positive T-Lymphocytes - immunology Protozoan Proteins - immunology Disease Models, Animal

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