Characterization of VSV-GP morphology by cryo-EM imaging and SEC-MALS

Mechanistic modeling of the elution behavior and convective entrapment of vesicular stomatitis virus on an ion exchange chromatography monolith

Developing a downstream purification process for replication-competent enveloped virus particles presents a significant challenge. This is largely due to the highly complex particle structures, as well as complexities of emerging purification modalities for such virus particles. In this study, an unexpected fluid-dynamic effect was observed during the elution of enveloped virus particles from an ion exchange chromatography monolith. This effect led to peak tailing and the separation of virus particle subpopulations. Upon considering possible causes, convective entrapment was identified as a plausible explanation. To investigate this effect, a mechanistic modeling approach representing the electrostatic resin interactions and the convective entrapment effect was implemented. The introduced Langmuir approximation of the convective entrapment showed good alignment with reference data from experiments. The model reproduced the retention effect, and furthermore suggested two virus particle populations due to the stronger retention effect on the tailing subpopulation caused by convective entrapment.

Navigating the Purification Process: Maintaining the Integrity of Replication-Competent Enveloped Viruses

Replication-competent virus particles hold significant therapeutic potential in application as oncolytic viruses or cancer vaccines. Ensuring the viral integrity of these particles is crucial for their infectivity, safety, and efficacy. Enveloped virus particles, in particular, offer large gene insert capacities and customizable target specificity. However, their sensitivity to environmental factors presents challenges in bioprocessing, potentially compromising high quality standards and cost-effective production. This review provides an in-depth analysis of the purification process steps for replication-competent enveloped virus particles, emphasizing the importance of maintaining viral integrity. It evaluates bioprocessing methods from cell culture harvest to final sterile filtration, including centrifugation, chromatographic, and filtration purification techniques. Furthermore, the manuscript delves into formulation and storage strategies necessary to preserve the functional and structural integrity of virus particles, ensuring their long-term stability and therapeutic efficacy. To assess the impact of process steps on particles and determine their quality and integrity, advanced analytical methods are required. This review evaluates commonly used methods for assessing viral integrity, such as infectious titer assays, total virus particle quantification, and structural analysis. By providing a comprehensive overview of the current state of bioprocessing for replication-competent enveloped virus particles, this review aims to guide researchers and industry professionals in developing robust and efficient purification processes. The insights gained from this analysis will contribute to the advancement of virus-based therapeutics, ultimately supporting the development of safe, effective, and economically viable treatments for various diseases.