Locke Emily, Flores-Garcia Yevel, Mayer Bryan T, MacGill Randall S, Borate Bhavesh, Salgado-Jimenez Berenice, Gerber Monica W, Mathis-Torres Shamika, Shapiro Sarah, King C Richter, Zavala Fidel
Center for Vaccine Innovation and Access, PATH, Washington, DC, 20001, USA.
Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
NPJ Vaccines. 2024 Feb 10;9(1):29. doi: 10.1038/s41541-024-00819-x.
New strategies are needed to reduce the incidence of malaria, and promising approaches include vaccines targeting the circumsporozoite protein (CSP). To improve upon the malaria vaccine, RTS,S/AS01, it is essential to standardize preclinical assays to measure the potency of next-generation vaccines against this benchmark. We focus on RTS,S/AS01-induced antibody responses and functional activity in conjunction with robust statistical analyses. Transgenic Plasmodium berghei sporozoites containing full-length P. falciparum CSP (tgPb-PfCSP) allow two assessments of efficacy: quantitative reduction in liver infection following intravenous challenge, and sterile protection from mosquito bite challenge. Two or three doses of RTS,S/AS01 were given intramuscularly at 3-week intervals, with challenge 2-weeks after the last vaccination. Minimal inter- and intra-assay variability indicates the reproducibility of the methods. Importantly, the range of this model is suitable for screening more potent vaccines. Levels of induced anti-CSP antibody 2A10 equivalency were also associated with activity: 105 μg/mL (95% CI: 68.8, 141) reduced liver infection by 50%, whereas 285 μg/mL (95% CI: 166, 404) is required for 50% sterile protection from mosquito bite challenge. Additionally, the liver burden model was able to differentiate between protected and non-protected human plasma samples from a controlled human malaria infection study, supporting these models' relevance and predictive capability. Comparison in animal models of CSP-based vaccine candidates to RTS,S/AS01 is now possible under well controlled conditions. Assessment of the quality of induced antibodies, likely a determinant of durability of protection in humans, should be possible using these methods.
需要新的策略来降低疟疾的发病率,有前景的方法包括针对环子孢子蛋白(CSP)的疫苗。为了改进疟疾疫苗RTS,S/AS01,必须标准化临床前检测,以根据这一基准来衡量下一代疫苗的效力。我们结合强大的统计分析,重点研究RTS,S/AS01诱导的抗体反应和功能活性。含有全长恶性疟原虫CSP的转基因伯氏疟原虫子孢子(tgPb-PfCSP)可以进行两项疗效评估:静脉注射攻击后肝脏感染的定量减少,以及免受蚊虫叮咬攻击的无菌保护。每隔3周肌肉注射两剂或三剂RTS,S/AS01,在最后一次接种疫苗后2周进行攻击。检测间和检测内的变异性最小,表明了这些方法的可重复性。重要的是,该模型的范围适用于筛选更有效的疫苗。诱导的抗CSP抗体2A10等效水平也与活性相关:105μg/mL(95%CI:68.8,141)可使肝脏感染减少50%,而对于免受蚊虫叮咬攻击的50%无菌保护,则需要285μg/mL(95%CI:166,404)。此外,肝脏负荷模型能够区分来自受控人类疟疾感染研究的受保护和未受保护的人类血浆样本,支持了这些模型的相关性和预测能力。现在可以在严格控制的条件下,在动物模型中比较基于CSP的候选疫苗与RTS,S/AS01。使用这些方法应该能够评估诱导抗体的质量,而诱导抗体的质量可能是人类保护持久性的一个决定因素。
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