病毒载体表征

细胞和基因治疗利用基因传递工具来进行治疗疾病。腺相关病毒(AAV)具有免疫原性低,宿主范围广泛,体内表达基因时间长等优点,许多基因治疗公司开始采用AAV作为首选的基因传递工具。因为病毒衣壳可以被修改从而携带治疗性药物,研究人员首先需要确定完整病毒衣壳的百分比,然后进一步了解有多少完整的病毒载体是满载的 (full capsid),这些分析表征和质控对治疗的成功至关重要。

empty capsid, partial capsid, full capsid the ultimate goal viral vector characterization with auc

对于研究人员来说,了解这些粒子的病毒载负尤为重要,因为不包含全靶治疗基因的病毒颗粒不太可能产生治疗活性,相反,这些部分衣壳可能引起不良反应,如免疫原性反应。研究人员需要了解给定病毒制备的质量和纯度,许多研究人员开始通过技术来获得这些信息。

测量rAAV载体均质性、纯度(及更多)的解决方案:分析溶液中的病毒颗粒。

基于重组腺相关病毒载体(rAAV)的基因治疗法充满了广阔的治疗前景,但正如基因治疗研究人员所知,在产品早期开发过程中遭遇失败是必经之路,产品质量的监控往往面临着重重考验。

虽然经典技术如动态光散射 (DLS) 或高效液相色谱(HPLC) 可以表征重组腺相关病毒载体(rAAV)的异质性和聚集状态,但它们并不足以提供足够的分辨率来量化均一性和病毒颗粒载荷。在生产临床级rAAV载体时,一直以来所面临的困难就是如何实现高分辨率表征。与其他常用技术不同,采用分析型超速离心技术 (SV-AUC)使生产临床级rAAV载体成为可能。

作为准确检测有效遗传的病毒载体的质控手段,在天然溶液环境中使用分析型超速离心技术(AUC)可以实现对制备的rAAV载体进行无培养基分析(独立于血清型和转基因),获得的信息诸如:

  • 表征生产过程中的产物,帮助确定去除空颗粒的方法;
  • 监测AAV载体结构的异质性、聚集状态;
  • 区分、量化样品中的多个组分,包括空病毒颗粒、包含全基因组病毒颗粒、包含部分基因组病毒载体、载体碎片、基因组碎片等;
  • 筛选病毒载体生产方法、进行扩大生产后的质控、检测批次间一致性;

观看此网络研讨会,了解 Genethon研究所的 Christine LE BEC 和她的团队如何使用 AUC 成功表征 scAAV 和 ssAAV 载体,包括均一性和病毒颗粒载荷。

 
 

用于表征病毒载体的产品:

Optima AUC 分析型超速离心机

Optima AUC分析型超速离心机

病毒载体 QC 中经常使用新一代 AUC以得到空的、完整包裹的和部分包裹的衣壳的相对量/百分比

Analytical Methods to Measure Empty and Full AAV Particles

 

As gene therapy approaches usually require large amounts of AAV vectors for clinical use, few manufacturing processes have been reported to provide high titer and potent quantities of products. The dose control of AAV vectors is commonly established on titration methods relying either on the quantitation of DNA (viral genome) or transgene expression following cell transduction (infectious genome). However, AAV vector lots are generally a heterogeneous mixture of empty particles (i.e. do not contain DNA) and full particles (i.e. contain DNA). Therefore, it could be considered that empty particles are product related impurities, which can impact on the immunogenicity profile of the product when high doses are administered to patients. Different indirect methods can be used to establish the ratio between full and empty AAV particles. The quantification of full capsids is performed by using qPCR based technology. The total particles can be evaluated by an ELISA assay, spectrometric analysis, ion-exchange chromatography or SDS-PAGE. However, these methods have limitations and are not applicable to all serotypes without performing a new development. Using analytical ultracentrifugation approach, we have developed a method to quantify simultaneously empty and full AAV particles as well as intermediate species containing fragmented or incomplete vector genome. We have applied this technique to AAV lots of different serotypes, several sizes of transgene and different process of production. Several examples of AAV vectors analysis will be presented showing that AUC could be implemented as a routine test to monitor AAV product quality and manufacturing consistency.

Content and Resources

Virus Purification Workflow – Centrifugation Highlights Centrifuge to harvest cells containing virus
Analytical Ultracentrifugation - Macromolecule Characterization in Solution (Biopharma) Beckman Coulter delivered the first AUC sample characterization tool to the scientific community powering discoveries