Mechanisms of protective immune responses induced by the Plasmodium falciparum circumsporozoite protein-based, self-assembling protein nanoparticle vaccine
Mechanisms of protective immune responses induced by the Plasmodium falciparum circumsporozoite protein-based, self-assembling protein nanoparticle vaccine
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DOI：
10.1186/1475-2875-12-136
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发表时间：
2013-04-22
期刊：
影响因子：
3
通讯作者：
Lanar, David E.
中科院分区：
文献类型：
--
作者：
McCoy, Margaret E.;Golden, Hannah E.;Lanar, David E.
背景资料：缺乏明确的疟疾免疫相关性，加上无法在人类宿主中诱导长寿命的无菌免疫应答，表明需要更好地理解增强疫苗效力的潜在保护性免疫机制。已经使用转基因修饰的伯氏疟原虫子孢子（Tg-Pb/PfCSP）和呈递CSP表位的自组装蛋白纳米颗粒（SAPN）疫苗（PfCSP-SAPN）实现了针对恶性疟原虫环子孢子蛋白（CSP）的保护性无菌免疫（>90%）。在这里，几个可能的机制参与独立的保护性体液和细胞反应诱导SAPN immunois.Methods：近交系小鼠接种PfCSP-SAPN在PBS中。收集血清抗体，并使用相差显微镜检查对恶性疟原虫子孢子移动性和完整性的影响。还检查了SAP诱导的抗体抑制原代人肝细胞内子孢子侵入和生长的功能。分别用共聚焦显微镜和电子显微镜观察了骨髓来源的树突状细胞（BMDDC）对SAPN的内部加工，包括细胞器特异性荧光标记抗体和金包封SAPN。这项工作的结果表明，PfCSP-SAPN诱导表位特异性抗体滴度，主要是Th 2同种型IgG 1，并且来自PfCSP-SAPN免疫的小鼠的血清抗体似乎通过补体的经典途径靶向恶性疟原虫子孢子。这导致子孢子死亡，如运动停止和环子孢子沉淀反应所示。此外，PfCSP-SAPN诱导的抗体能够抑制野生型恶性疟原虫子孢子在培养的原代人肝细胞内的侵袭和生长。此外，观察到PfCSP-SAPN被加工，树突状细胞以缓慢和连续的方式通过与抗原加工相关的转运蛋白（TAP）募集到早期核内体（EE）并部分延迟通过内质网的加工，将CD 8（+）T细胞（并呈递）给免疫系统，具有诱导如前所述的长寿命效应记忆CD 8（+）T细胞的潜力。本文描述了由PfCSP-SAPN疫苗接种诱导的体液和细胞免疫机制的检查，其导致针对表达恶性疟原虫CSP的转基因伯氏疟原虫子孢子的无菌宿主保护，并且显著抑制天然恶性疟原虫子孢子在培养的人肝细胞内侵入和发育。这些结果可能表明控制恶性疟原虫子孢子感染人类所需的保护性抗体的类型和作用方式，以及诱导保护性长寿效应记忆CD 8（+）T细胞的潜在机制。
Background: A lack of defined correlates of immunity for malaria, combined with the inability to induce long-lived sterile immune responses in a human host, demonstrate a need for improved understanding of potentially protective immune mechanisms for enhanced vaccine efficacy. Protective sterile immunity (>90%) against the Plasmodium falciparum circumsporozoite protein (CSP) has been achieved using a transgenically modified Plasmodium berghei sporozoite (Tg-Pb/PfCSP) and a self-assembling protein nanoparticle (SAPN) vaccine presenting CSP epitopes (PfCSP-SAPN). Here, several possible mechanisms involved in the independently protective humoral and cellular responses induced following SAPN immunization are described.Methods: Inbred mice were vaccinated with PfCSP-SAPN in PBS. Serum antibodies were harvested and effects on P. falciparum sporozoites mobility and integrity were examined using phase contrast microscopy. The functionality of SAPN-induced antibodies on inhibition of sporozoite invasion and growth within primary human hepatocytes was also examined. The internal processing of SAPN by bone marrow-derived dendritic cells (BMDDC), using organelle-specific, fluorescent-tagged antibody or gold-encapsulated SAPN, was observed using confocal or electron microscopy, respectively.Results: The results of this work demonstrate that PfCSP-SAPN induces epitope-specific antibody titers, predominantly of the Th2 isotype IgG1, and that serum antibodies from PfCSP-SAPN-immunized mice appear to target P. falciparum sporozoites via the classical pathway of complement. This results in sporozoite death as indicated by cessation of motility and the circumsporozoite precipitation reaction. Moreover, PfCSP-SAPN-induced antibodies are able to inhibit wild-type P. falciparum sporozoite invasion and growth within cultured primary human hepatocytes. In addition, the observation that PfCSP-SAPN are processed (and presented) to the immune system by dendritic cells in a slow and continuous fashion via transporter associated with antigen processing (TAP) recruitment to the early endosome (EE), and have partially delayed processing through the endoplasmic reticulum, has the potential to induce the long-lived, effector memory CD8(+) T-cells as described previously.Conclusion: This paper describes the examination of humoral and cellular immune mechanisms induced by PfCSP-SAPN vaccination which result in sterile host protection against a transgenic P. berghei malaria sporozoite expressing the P. falciparum CSP, and which significantly inhibits native P. falciparum sporozoites from invading and developing within cultured human hepatocytes. These results may indicate the type and mode of action of protective antibodies needed to control P. falciparum sporozoites from infecting humans as well as a potential mechanism of induction of protective long-lived effector memory CD8(+) T-cells.