Concentration and purification of rubella virus using monolithic chromatographic support

Vaccine process technology-A decade of progress

In the past decade, new approaches to the discovery and development of vaccines have transformed the field. Advances during the COVID-19 pandemic allowed the production of billions of vaccine doses per year using novel platforms such as messenger RNA and viral vectors. Improvements in the analytical toolbox, equipment, and bioprocess technology have made it possible to achieve both unprecedented speed in vaccine development and scale of vaccine manufacturing. Macromolecular structure-function characterization technologies, combined with improved modeling and data analysis, enable quantitative evaluation of vaccine formulations at single-particle resolution and guided design of vaccine drug substances and drug products. These advances play a major role in precise assessment of critical quality attributes of vaccines delivered by newer platforms. Innovations in label-free and immunoassay technologies aid in the characterization of antigenic sites and the development of robust in vitro potency assays. These methods, along with molecular techniques such as next-generation sequencing, will accelerate characterization and release of vaccines delivered by all platforms. Process analytical technologies for real-time monitoring and optimization of process steps enable the implementation of quality-by-design principles and faster release of vaccine products. In the next decade, the field of vaccine discovery and development will continue to advance, bringing together new technologies, methods, and platforms to improve human health.

Critical Assessment of Purification and Analytical Technologies for Enveloped Viral Vector and Vaccine Processing and Their Current Limitations in Resolving Co-Expressed Extracellular Vesicles

Viral vectors and viral vaccines are invaluable tools in prevention and treatment of diseases. Many infectious diseases are controlled using vaccines designed from subunits or whole viral structures, whereas other genetic diseases and cancers are being treated by viruses used as vehicles for delivering genetic material in gene therapy or as therapeutic agents in virotherapy protocols. Viral vectors and vaccines are produced in different platforms, from traditional embryonated chicken eggs to more advanced cell cultures. All these expression systems, like most cells and cellular tissues, are known to spontaneously release extracellular vesicles (EVs). EVs share similar sizes, biophysical characteristics and even biogenesis pathways with enveloped viruses, which are currently used as key ingredients in a number of viral vectors and licensed vaccine products. Herein, we review distinctive features and similarities between EVs and enveloped viruses as we revisit the downstream processing steps and analytical technologies currently implemented to produce and document viral vector and vaccine products. Within a context of well-established viral vector and vaccine safety profiles, this review provides insights on the likely presence of EVs in the final formulation of enveloped virus products and discusses the potential to further resolve and document these components.

Purification of cell-derived Japanese encephalitis virus by dual-mode chromatography

Purification of the enveloped virus poses a challenge as one must retain viral infectivity to preserve immunogenicity. The traditional process of virus purification is time-consuming, laborious and hard to scale up. Here, a rapid, simple and extensible laboratory program for the purification of Japanese encephalitis virus (JEV) was developed by using differential centrifugation, ultrafiltration, Sepharose 4 fast flow gel chromatography, and Capto^TM Core 700 chromatography. The entire process recovered 61.64% of the original virus, and the purified virus particles maintained good activity and immunogenicity. The purification process described has potential application in large-scale production of high-purity JEV.

Polysaccharide-based chromatographic adsorbents for virus purification and viral clearance

Viruses still pose a significant threat to human and animal health worldwide. In the fight against viral infections, high-purity viral stocks are needed for manufacture of safer vaccines. It is also a priority to ensure the viral safety of biopharmaceuticals such as blood products. Chromatography techniques are widely implemented at both academic and industrial levels in the purification of viral particles, whole viruses and virus-like particles to remove viral contaminants from biopharmaceutical products. This paper focuses on polysaccharide adsorbents, particulate resins and membrane adsorbers, used in virus purification/removal chromatography processes. Different chromatographic modes are surveyed, with particular attention to ion exchange and affinity/pseudo-affinity adsorbents among which commercially available agarose-based resins (Sepharose®) and cellulose-based membrane adsorbers (Sartobind®) occupy a dominant position. Mainly built on the development of new ligands coupled to conventional agarose/cellulose matrices, the development perspectives of polysaccharide-based chromatography media in this antiviral area are stressed in the conclusive part.

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Chromatography has been and is still extensively implemented in virus purification/removal downstream processes.

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Typical application fields are the manufacturing of purified viral vaccines and virus-free biopharmaceuticals.

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Agarose and cellulose remain the primary polysaccharide bases for chromatography adsorbents in such virus-related applications.

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Present R&D studies mainly focus on multimodal chromatography and affinity ligands.

Opportunities to debottleneck the downstream processing of the oncolytic measles virus

Oncolytic viruses (including measles virus) offer an alternative approach to reduce the high mortality rate of late-stage cancer. Several measles virus strains infect and lyse cancer cells efficiently, but the broad application of this therapeutic concept is hindered by the large number of infectious particles required (10⁸-10¹² TCID₅₀ per dose). The manufacturing process must, therefore, achieve high titers of oncolytic measles virus (OMV) during upstream production and ensure that the virus product is not damaged during purification by applying appropriate downstream processing (DSP) unit operations. DSP is currently a production bottleneck because there are no specific platforms for OMV. Infectious OMV must be recovered as intact, enveloped particles, and host cell proteins and DNA must be reduced to acceptable levels to meet regulatory guidelines that were developed for virus-based vaccines and gene therapy vectors. Handling such high viral titers and process volumes is technologically challenging and expensive. This review considers the state of the art in OMV purification and looks at promising DSP technologies. We discuss here the purification of other enveloped viruses where such technologies could also be applied to OMV. The development of DSP technologies tailored for enveloped viruses is necessary to produce sufficient titers for virotherapy, which could offer hope to millions of patients suffering from incurable cancer.

Asymmetrical flow field-flow fractionation in purification of an enveloped bacteriophage ϕ6

Basic and applied virus research requires specimens that are purified to high homogeneity. Thus, there is much interest in the efficient production and purification of viruses and their subassemblies. Advances in the production steps have shifted the bottle neck of the process to the purification. Nonetheless, the development of purification techniques for different viruses is challenging due to the complex biological nature of the infected cell cultures as well as the biophysical and -chemical differences in the virus particles. We used bacteriophage ϕ6 as a model virus in our attempts to provide a new purification method for enveloped viruses. We compared asymmetrical flow field-flow fractionation (AF4)-based virus purification method to the well-established ultracentrifugation-based purification of ϕ6. In addition, binding of ϕ6 virions to monolithic anion exchange columns was tested to evaluate their applicability in concentrating the AF4 purified specimens. Our results show that AF4 enables one-hour purification of infectious enveloped viruses with specific infectivity of ~1 × 10¹³ PFU/mg of protein and ~65-95% yields. Obtained purity was comparable with that obtained using ultracentrifugation, but the yields from AF4 purification were 2-3-fold higher. Importantly, high quality virus preparations could be obtained directly from crude cell lysates. Furthermore, when used in combination with in-line light scattering detectors, AF4 purification could be coupled to simultaneous quality control of obtained virus specimen.

Recovery of infective virus particles in ion-exchange and hydrophobic interaction monolith chromatography is influenced by particle charge and total-to-infective particle ratio

Viral particles are used in medical applications as vaccines or gene therapy vectors. In order to obtain product of high purity, potency and safety for medical use purification of virus particles is a prerequisite, and chromatography is gaining increased attention to meet this aim. Here, we report on the use of ion-exchange and hydrophobic interaction chromatography on monolithic columns for purification of mumps virus (MuV) and measles virus (MeV). Efficiency of the process was monitored by quantification of infective virus particles (by 50% cell culture infective dose assay) and total virus particles, and monitoring of their size (by Nanoparticle Tracking Analysis). Ion-exchange chromatography was shown to be inefficient for MuV and best results for MeV were obtained on QA column with recovery around 17%. Purification of MuV and MeV by hydrophobic interaction chromatography resulted in recoveries around 60%. Results showed that columns with small channels (d=1.4μm) are not suitable for MuV and MeV, although their size is below 400nm, whereas columns with large channels (6μm) showed to be efficient and recoveries independent on the flow rate up to 10mL/min. Heterogeneity of the virus suspension and its interday variability mostly regarding total-to-infective particle ratio was observed. Interestingly, a trend in recovery depending on the day of the harvest was also observed for both viruses, and it correlated with the total-to-infective particle ratio, indicating influence of the virus sample composition on the chromatography results.

Stability of Minimum Essential Medium functionality despite L-glutamine decomposition

L-Glutamine (L-Gln) instability in liquid media is a well-known fact. Also, negative effect of ammonia, one of the L-Gln degradation products, on viability of many cell cultures and on replication of different viruses has been described. However, negative effects of ammonia have been reported in doses excessively exceeding those that could be generated in regularly used liquid culture media due to spontaneous L-Gln breakdown (below 2 mM). Traditional virus vaccine production processes have been established and registered involving L-Gln containing media use. Eventual culture media replacement in the regular production process belongs to the major regulative changes that require substantial financial expenses. The aim of this study was to evaluate the effect of storage of Minimum Essential Media with Hanks salts on their relevant biological functions during virus vaccine production process in relation to L-Gln decrease. Our results show a cell type dependent effect of spontaneous L-Gln degradation during medium storage. They also suggest that for cell cultures used in measles, mumps, and rubella virus production the media retain their functionality in respect to cell viability or virus growth over a certain time window despite L-Gln degradation.

Biobased monoliths for adenovirus purification

Adenoviruses are important platforms for vaccine development and vectors for gene therapy, increasing the demand for high titers of purified viral preparations. Monoliths are macroporous supports regarded as ideal for the purification of macromolecular complexes, including viral particles. Although common monoliths are based on synthetic polymers as methacrylates, we explored the potential of biopolymers processed by clean technologies to produce monoliths for adenovirus purification. Such an approach enables the development of disposable and biodegradable matrices for bioprocessing. A total of 20 monoliths were produced from different biopolymers (chitosan, agarose, and dextran), employing two distinct temperatures during the freezing process (-20 °C and -80 °C). The morphological and physical properties of the structures were thoroughly characterized. The monoliths presenting higher robustness and permeability rates were further analyzed for the nonspecific binding of Adenovirus serotype 5 (Ad5) preparations. The matrices presenting lower nonspecific Ad5 binding were further functionalized with quaternary amine anion-exchange ligand glycidyltrimethylammonium chloride hydrochloride by two distinct methods, and their performance toward Ad5 purification was assessed. The monolith composed of chitosan and poly(vinyl) alcohol (50:50) prepared at -80 °C allowed 100% recovery of Ad5 particles bound to the support. This is the first report of the successful purification of adenovirus using monoliths obtained from biopolymers processed by clean technologies.

Improved virus purification processes for vaccines and gene therapy

The downstream processing of virus particles for vaccination or gene therapy is becoming a critical bottleneck as upstream titers keep improving. Moreover, the growing pressure to develop cost-efficient processes has brought forward new downstream trains. This review aims at analyzing the state-of-the-art in viral downstream purification processes, encompassing the classical unit operations and their recent developments. Emphasis is given to novel strategies for process intensification, such as continuous or semi-continuous systems based on multicolumn technology, opening up process efficiency. Process understanding in the light of the pharmaceutical quality by design (QbD) initiative is also discussed. Finally, an outlook of the upcoming breakthrough technologies is presented.

Downstream processing and chromatography based analytical methods for production of vaccines, gene therapy vectors, and bacteriophages

Downstream processing of nanoplexes (viruses, virus-like particles, bacteriophages) is characterized by complexity of the starting material, number of purification methods to choose from, regulations that are setting the frame for the final product and analytical methods for upstream and downstream monitoring. This review gives an overview on the nanoplex downstream challenges and chromatography based analytical methods for efficient monitoring of the nanoplex production.

Concentration and purification of enterovirus 71 using a weak anion-exchange monolithic column

BACKGROUND

Enterovirus 71 (EV-71) is a neurotropic virus causing Hand, Foot and Mouth Disease (HFMD) in infants and children under the age of five. It is a major concern for public health issues across Asia-Pacific region. The most effective way to control the disease caused by EV-71 is by vaccination thus a novel vaccine is urgently needed. Inactivated EV-71 induces a strong, virus-neutralizing antibody response in animal models, protecting them against a lethal EV-71 challenge and it has been shown to elicit cross-neutralizing antibodies in human trials. Hence, the large-scale production of purified EV-71 is required for vaccine development, diagnosis and clinical trials.

METHODS

CIM® Monolith columns are single-piece columns made up of poly(glycidyl methacrylate co-ethylene dimethacrylate) as support matrix. They are designed as porous channels rather than beads with different chemistries for different requirements. As monolithic columns have a high binding capacity, flow rate and resolution, a CIM® DEAE-8f tube monolithic column was selected for purification in this study. The EV-71 infected Rhabdomyosarcoma (RD) cell supernatant was concentrated using 8% PEG 8000 in the presence of 400 mM sodium chloride. The concentrated virus was purified by weak anion exchange column using 50 mM HEPES + 1 M sodium chloride as elution buffer.

RESULTS

Highly pure viral particles were obtained at a concentration of 350 mM sodium chloride as confirmed by SDS-PAGE and electron microscopy. Presence of viral proteins VP1, VP2 and VP3 was validated by western blotting. The overall process achieved a recovery of 55%.

CONCLUSIONS

EV-71 viral particles of up to 95% purity can be recovered by a single step ion-exchange chromatography using CIM-DEAE monolithic columns and 1 M sodium chloride as elution buffer. Moreover, this method is scalable to purify several litres of virus-containing supernatant, using industrial monolithic columns with a capacity of up to 8 L such as CIM® cGMP tube monolithic columns.

A monolith purification process for virus-like particles from yeast homogenate

Monoliths are an alternative stationary phase format to conventional particle based media for large biomolecules. Conventional resins suffer from limited capacities and flow rates when used for viruses, virus-like particles (VLP) and other nanoplex materials. The monolith structure provides a more open pore structure to improve accessibility for these materials and better mass transport from convective flow and reduced pressure drops. To examine the performance of this format for bioprocessing we selected the challenging capture of a VLP from clarified yeast homogenate. Using a recombinant Saccharomyces cerevisiae host it was found hydrophobic interaction based separation using a hydroxyl derivatised monolith had the best performance. The monolith was then compared to a known beaded resin method, where the dynamic binding capacity was shown to be three-fold superior for the monolith with equivalent 90% recovery of the VLP. To understand the impact of the crude feed material confocal microscopy was used to visualise lipid contaminants, deriving from the homogenised yeast. It was seen that the lipid formed a layer on top of the column, even after regeneration of the column with isopropanol, resulting in increasing pressure drops with the number of operational cycles. Removal of the lipid pre-column significantly reduces the amount and rate of this fouling process. Using Amberlite/XAD-4 beads around 70% of the lipid was removed, with a loss of VLP around 20%. Applying a reduced lipid feed versus an untreated feed further increased the dynamic binding capacity of the monolith from 0.11 mg/mL column to 0.25 mg/mL column.