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• Oligo-dA binding assay was developed for characterization of monolith OdT columns. • Coupling ≥ 2.5 probes of 18-mer OdT per 100 nm2 is optimal for mRNA chromatography. • Increased mRNA residence time is needed to utilize the full capacity of OdT column. • Up to 5 mg/mL mRNA dynamic binding capacity was achieved at 1 min residence time. • Oligo-dT monolith column enables efficient gram-scale mRNA purification. Oligo-deoxythymidilic acid (OdT) probes conjugated to solid-phase supports exhibit high affinity for poly-adenylated mRNA (target) through high-affinity base-pairing interactions. Here we report the development of a OdT-functionalized chromatographic monolith for purification of polyadenylated mRNA and development of purification methods to support large-scale purification of mRNA-based therapeutics. We report the development of a chromatographic assay based on a synthetic oligo-deoxyadenylic acid chain of 10 or 20 nucleotides (OdA10 and OdA20) as a surrogate for polyadenylated mRNA, which was used for optimization of the OdT affinity column (i.e. the amount and structure of OdT immobilized and monolithic channel size). OdA hybridization to OdT monoliths correlated well with the amount of immobilized OdT, while an in-depth analysis revealed that hybridization yield decreased with increasing size of the target, temperature and probe surface coverage. OdA hybridization kinetics was flow rate-independent, confirming convection-based mass transport within the monolith's channels. The demonstrated steep adsorption isotherms enable chromatographic capture of even highly diluted OdA-containing molecules. Dynamic binding capacity for model mRNA was independent of OdT length and amount of immobilized OdT probes above a critical threshold but was highly influenced by the composition of the binding buffer and mRNA residence time. We demonstrated the scalability of the mRNA purification process with OdT monoliths from 0.1 mL to at least 800 mL bed volume, paving the way for manufacturing processes on OdT monoliths with 40 L bed volume. [ABSTRACT FROM AUTHOR]

Highlights: [•] Aptamer selection is often hindered due to accompanying adverse effects. [•] Assays are described for measuring aptamer pool complexity and binding affinity. [•] Methods are compared using anti-streptavidin aptamer selection as model. [Copyright &y& Elsevier]

The human papillomavirus (HPV) minor capsid protein L2 plays important roles in the generation of infectious viral particles and in the initial steps of infection. Here we show that HPV-16 L2 protein is sumoylated at lysine 35 and that sumoylation affects its stability. Interestingly, the sumoylated form of L2 cannot bind to the major capsid protein L1, suggesting a mechanism by which capsid assembly may be modulated in an infected cell. Additionally, L2 appears to modulate the overall sumoylation status of the host cell. These observations indicate a complex interplay between the HPV L2 protein and the host sumoylation machinery. [ABSTRACT FROM AUTHOR]

The recent clinical success of messenger RNA (mRNA) technology in managing the Covid pandemic has triggered an unprecedented innovation in production and analytical technologies for this therapeutic modality. mRNA is produced by enzymatic transcription of plasmid DNA (pDNA) using polymerase in a cell-free process of in vitro transcription. After transcription, the pDNA is considered a process-related impurity and is removed from the mRNA product enzymatically, chromatographically, or by precipitation. Regulatory requirements are currently set at 10 ng of template pDNA per single human dose, which typically ranges between 30 and 100 µg. Here, we report the development of a generic procedure based on enzymatic digestion and chromatographic separation for the determination of residual pDNA in mRNA samples, with a limit of quantification of 2.3 ng and a limit of detection of less than 0.1 ng. The procedure is based on enzymatic degradation of mRNA and anion exchange HPLC separation, followed by quantification of residual pDNA with a chromatographic method that is already widely adopted for pDNA quality analytics. The procedure has been successfully applied for in-process monitoring of three model mRNAs and a self-amplifying RNA (saRNA) and can be considered a generic substitution for qPCR in mRNA in-process control analytical strategy, with added benefits that it is more cost-efficient, faster, and sequence agnostic. [ABSTRACT FROM AUTHOR]

The COVID‐19 pandemic triggered an unprecedented surge in development of mRNA‐based vaccines. Despite the need to increase process productivity and thus decrease the cost of mRNA vaccines, limited scientific literature is available on strategies to increase the yield of in vitro transcription (IVT) reaction, the unit operation with highest cost of goods, which has traditionally been performed as a batch reaction. Single‐use bioreactors are traditionally used for cell‐based production of biopharmaceuticals, but some core functionalities, such as controlled and automated feed addition, are potentially useful for cell‐free mRNA processes. We report the production of 2 g mRNA in an Ambr® 250 Modular bioreactor system with a starting volume of 100 mL, reaching a maximum mRNA concentration of 12 g L−1 by a fed‐batch IVT approach, and demonstrate the feasibility of continuous fed‐batch production, paving the way towards continuous manufacturing of mRNA. [ABSTRACT FROM AUTHOR]

HPLC is established as a fast convenient analytical technology for characterizing the content of empty and full capsids in purified samples containing adeno-associated virus (AAV). UV-based monitoring unfortunately over-estimates the proportion of full capsids and offers little value for characterizing unpurified samples. The present study combines dual-wavelength UV monitoring with intrinsic fluorescence, extrinsic fluorescence, and light-scattering to extend the utility of HPLC for supporting development of therapeutic AAV-based drugs. Applications with anion exchange (AEC), cation exchange (CEC), and size exclusion chromatography (SEC) are presented. Intrinsic fluorescence increases sensitivity of AAV detection over UV and enables more objective estimation of empty and full capsid ratios by comparison of their respective peak areas. Light scattering enables identification of AAV capsids in complex samples, plus semiquantitative estimation of empty and full capsid ratios from relative peak areas of empty and full capsids. Extrinsic Picogreen fluorescence enables semiquantitative tracking of DNA with all HPLC methods at all stages of purification. It does not detect encapsidated DNA but reveals DNA associated principally with the exteriors of empty capsids. It also enables monitoring of host DNA contamination across chromatograms. These enhancements support many opportunities to improve characterization of raw materials and process intermediates, to accelerate process development, provide rapid in-process monitoring, and support process validation. [ABSTRACT FROM AUTHOR]