Supplementary materials for PhD thesis “Analysis of DNA and recombinant viral vaccines against P. falciparum in malaria-naïve and malaria-exposed humans”

This dataset comprises the contents of a CD-ROM which was attached to the thesis when it was submitted in 2004. It was uploaded to ORDO in 2024 for preservation purposes. The files contain confidential information so have not been published. For more information, please refer to the thesis “Analysis of DNA and recombinant viral vaccines against P. falciparum in malaria-naïve and malaria-exposed humans” on ORO.The hypotheses under test were as follows. Firstly that sequential immunisation of humans with two candidate vaccines recombinant for the same malarial DNA sequence would be safe, would produce higher frequencies of antigen-specific T cells in peripheral blood and greater efficacy than repeated immunisation with one vaccine. Secondly that recombinant viral malaria immunization would be more immunogenic in malaria-exposed than malaria-naive individuals. The third hypothesis was contingent on the conduct of a field efficacy trial; liver-stage specific T cells induced by the regimen with greatest immunogenicity would provide protection against natural infection. Three delivery systems were evaluated - a circular plasmid DNA molecule (DNA), modified vaccinia virus Ankara (MVA) and fowlpox strain 9 (FP9); each recombinant for the multiple epitope - thrombospondin related anonymous (or adhesion) protein (ME-TRAP) P. falciparum DNA sequence. DNA ME-TRAP and MVA ME-TRAP were safe but poorly immunogenic when given alone in both UK and Gambian adults. Two doses of 1mg DNA ME-TRAP administered intramuscularly followed by one dose of 3 x 107 plaque forming units (pfu) MVA ME-TRAP administered intradermally induced higher effector T cell frequencies as measured by ex vivo γ-interferon ELISPOT (enzyme-linked immunospot) assay than three doses of either alone. A second MVA ME-TRAP immunisation did not increase immunogenicity above that after a single immunisation. At these doses the DNA/MVA regimen was more immunogenic in malaria-experienced Gambian adults than in malaria-naive British adults. Increasing the dose of DNA to 2mg and MVA to 1.5 x 108 pfu increased immunogenicity further. Two doses of FP9 ME-TRAP showed a trend towards to being less immunogenic than two doses of DNA ME-TRAP prior to a single MVA immunisation. The heterologous DNA/MVA regimen afforded protection manifested by delay in time to parasitaemia in a clinical challenge model in the UK. Therefore a randomised double-blind controlled trial was conducted in men aged 15 45 in The Gambia. This trial confirmed safety and high immunogenicity but there was 10.3% (95%CI -22% to +34%) efficacy for the time to infection primary endpoint. Potential reasons for failure of the intervention include an unfavourable CD4+/CD8+ T cell ratio, inadequate TRAP expression in infected hepatocytes, inadequate cross-reactivity and the duration or magnitude of the peak T cell immunogenicity.

本数据集囊括了2004年提交论文时所附带的CD-ROM内容。出于保存目的，该数据集于2024年被上传至ORDO。由于文件包含机密信息，故尚未公开发布。如需了解更多信息，请参阅位于ORO的论文《针对恶性疟原虫的DNA和重组病毒疫苗在无疟疾暴露和疟疾暴露人类中的分析》。论文中测试的假设如下。首先，对人类进行连续接种两种针对同一恶性疟原虫DNA序列的候选疫苗，预期将安全，并能在外周血中产生更高频率的抗原特异性T细胞，以及比重复接种一种疫苗更高的疗效。其次，重组病毒疟疾免疫在疟疾暴露者中比无疟疾暴露者中具有更高的免疫原性。第三个假设基于现场疗效试验的进行；由最高免疫原性方案诱导的肝期特异性T细胞将能提供对自然感染的保护。评估了三种递送系统——环状质粒DNA分子（DNA）、改良安卡拉痘苗病毒（MVA）和鸡痘菌株9（FP9）；每个系统均与多个表位——血栓素相关匿名（或粘附）蛋白（ME-TRAP）恶性疟原虫DNA序列重组。单独给予DNA ME-TRAP和MVA ME-TRAP在英国内部和冈比亚成年人均显示出安全性但免疫原性较差。通过肌肉注射给予1mg DNA ME-TRAP两次剂量，随后通过皮内注射给予3 x 10^7斑形成单位（pfu）的MVA ME-TRAP一次剂量，与单独给予三剂量的任何一种相比，可诱导更高的效应T细胞频率，这一结果是通过体外γ-干扰素ELISPOT（酶联免疫斑点）测定得到的。第二次MVA ME-TRAP免疫并未将免疫原性提高至单次免疫后的水平。在这些剂量下，DNA/MVA方案在疟疾暴露的冈比亚成年人与疟疾暴露的英国成年人中显示出更高的免疫原性。将DNA的剂量增加到2mg和将MVA的剂量增加到1.5 x 10^8 pfu进一步增加了免疫原性。FP9 ME-TRAP的两次剂量显示出在单次MVA免疫之前，其免疫原性低于DNA ME-TRAP的两次剂量。在临床挑战模型中，DNA/MVA异源方案提供了保护，表现为寄生虫血症时间延迟。因此，在冈比亚对15至45岁的男性进行了随机双盲对照试验。该试验证实了安全性及高免疫原性，但对于感染时间这一主要终点，其有效率为10.3%（95%CI -22%至+34%）。干预措施失败的可能原因包括不利的CD4+/CD8+ T细胞比率、感染肝细胞中TRAP表达不足、交叉反应性不足以及T细胞免疫原性峰值持续时间和强度。