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BACKGROUND: The T-cell mediated immune response plays a central role in the control of malaria after natural infection or vaccination. There is increasing evidence that T-cell responses are heterogeneous and that both the quality of the immune response and the balance between pro-inflammatory and regulatory T-cells determines the outcome of an infection. As Malaria parasites have been shown to induce immunosuppressive responses to the parasite and non-related antigens this study examined T-cell mediated pro-inflammatory and regulatory immune responses induced by malaria vaccination in children in an endemic area to determine if these responses were associated with vaccine immunogenicity. METHODS: Using real-time RT- PCR we profiled the expression of a panel of key markers of immunogenecity at different time points after vaccination with two viral vector vaccines expressing the malaria TRAP antigen (FP9-TRAP and MVA-TRAP) or following rabies vaccination as a control. PRINCIPAL FINDINGS: The vaccine induced modest levels of IFN-gamma mRNA one week after vaccination. There was also an increase in FoxP3 mRNA expression in both TRAP stimulated and media stimulated cells in the FFM ME-TRAP vaccine group; however, this may have been driven by natural exposure to parasite rather than by vaccination. CONCLUSION: Quantitative PCR is a useful method for evaluating vaccine induced cell mediated immune responses in frozen PBMC from children in a malaria endemic country. Future studies should seek to use vaccine vectors that increase the magnitude and quality of the IFN-gamma immune response in naturally exposed populations and should monitor the induction of a regulatory T cell response.

Original publication

DOI

10.1371/journal.pone.0008434

Type

Journal article

Journal

PLoS One

Publication Date

23/12/2009

Volume

4

Keywords

Antigens, Protozoan, Child, Child, Preschool, Clone Cells, Forkhead Transcription Factors, Gene Dosage, Gene Expression Regulation, Humans, Hypoxanthine Phosphoribosyltransferase, Immunity, Infant, Interferon-gamma, Kenya, Malaria Vaccines, Polymerase Chain Reaction, RNA, Messenger, Rabies Vaccines, Receptors, Thrombin, T-Lymphocytes, Time Factors, Vaccination