Adenovirus type 5 intrinsic adsorption rates measured by surface plasmon resonance

Advances and opportunities in process analytical technologies for viral vector manufacturing

Viral vectors are an emerging, exciting class of biologics whose application in vaccines, oncology, and gene therapy has grown exponentially in recent years. Following first regulatory approval, this class of therapeutics has been vigorously pursued to treat monogenic disorders including orphan diseases, entering hundreds of new products into pipelines. Viral vector manufacturing supporting clinical efforts has spurred the introduction of a broad swath of analytical techniques dedicated to assessing the diverse and evolving panel of Critical Quality Attributes (CQAs) of these products. Herein, we provide an overview of the current state of analytics enabling measurement of CQAs such as capsid and vector identities, product titer, transduction efficiency, impurity clearance etc. We highlight orthogonal methods and discuss the advantages and limitations of these techniques while evaluating their adaptation as process analytical technologies. Finally, we identify gaps and propose opportunities in enabling existing technologies for real-time monitoring from hardware, software, and data analysis viewpoints for technology development within viral vector biomanufacturing.

Lip balm drying promotes virus attachment: Characterization of lip balm coatings and XDLVO modeling

HYPOTHESIS

Drying-induced decrease in lip balm surface energy enhances virus adhesion due to the emergence of strong hydrophobic colloid-surface interactions.

EXPERIMENTS

A protocol was developed for preparing lip balm coatings to enable physicochemical characterization and adhesion studies. Surface charge and hydrophobicity of four brands of lip balm (dry and hydrated) and human adenovirus 5 (HAdV5) were measured and used to calculate the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) energy of interactions between lip balm coatings and HAdV5 as well as four other colloids: HAdV40, MS2 and P22 bacteriophages, and SiO2. Quartz crystal microbalance with dissipation monitoring (QCM-D) tests employed SiO2 colloids, HAdV5 and hydrated lip balms.

FINDINGS

Drying of lip balms results in a dramatic decrease of their surface energy (δΔGsws≥ 83.0 mJ/m2) making the surfaces highly hydrophobic. For dry lip balms, the interaction of the balm surface with all five colloids is attractive. For lip balms hydrated in 150 mM NaCl (ionic strength of human saliva), XDLVO calculations predict that hydrophilic colloids (MS2, P22, SiO2) may attach into shallow secondary minima. Due to the relative hydrophobicity of human adenoviruses, primary maxima in XDLVO profiles are low or non-existent making irreversible deposition into primary energy minima possible. Preliminary QCM-D tests with SiO2 colloids and HAdV5 confirm deposition on hydrated lip balms.

Impact of ligand density on the optimization of ion-exchange membrane chromatography for viral vector purification

The effect of ligand density on anion-exchange membrane chromatography (AEXmc) for the purification of recombinant baculoviruses (rBVs), potential viral vectors in clinical applications, is studied by surface plasmon resonance on customized AEX surfaces and gradient elution experiments on Sartobind D membrane prototypes with different diethylamine ligand densities, complemented by dynamic light scattering analysis for estimation of the hydrodynamic particle size of the various biologics. A chromatographic-column model based on the steric mass action model of ion exchange is employed to analyze the gradient-elution AEXmc experiments, extrapolate the results to other operating conditions, and provide directions for process improvement. Although counterintuitively, the experimental evidence provided in this study shows that the lowering of ligand density is beneficial for rBV purification by AEXmc in bind-and-elute-mode, because it decreases the residual concentrations of host cell protein, dsDNA, and non-infective rBVs in the eluted product cut, and increases the overall yield by roughly 20% over current standard values. Overall, we present a case study on how rational design can streamline downstream process development.

Modeling protein binding and elution over a chromatographic surface probed by surface plasmon resonance

Surface plasmon resonance (SPR) spectroscopy is used as a scaled-down, analytical, pseudo-chromatography tool for analyzing protein binding and elution over an ion-exchange surface under cyclic sorption conditions. A micrometric-scale adsorption surface was produced by immobilizing a typical ion exchange ligand--diethylaminoethyl (DEAE)--onto commercially available planar gold sensor chip surfaces pre-derivatized with a self-assembled monolayer of 11-mercaptoundecanoic acid with known density. An explicit mathematical formulation is provided for the deconvolution and interpretation of the SPR sensorgrams. An adsorption rate model is proposed to describe the SPR sensorgrams for bovine serum albumin, used here as model protein, when the DEAE surface is subjected to a cyclic series of binding and elution steps. Overall, we demonstrate that the adsorption rate model is capable of quantitatively describing BSA binding and elution for protein titers from dilute conditions up to overloaded conditions and a broad range of salt concentrations.

Methacrylate-based short monolithic columns: enabling tools for rapid and efficient analyses of biomolecules and nanoparticles

This review describes the novel chromatography stationary phase--a porous monolithic methacrylate-based polymer--in terms of the design of the columns and some of the features that make these columns attractive for the purification of large biomolecules. We first start with a brief summary of the characteristics of these large molecules (more precisely large proteins like immunoglobulins G and M, plasmid deoxyribonucleic acid (DNA), and viral particles), and a list of some of the problems that were encountered during the development of efficient purification processes. We then briefly describe the structure of the methacrylate-based monolith and emphasize the features which make them more than suitable for dealing with large entities. The highly efficient structure on a small scale can be transferred to a large scale without the need of making column modifications, and the various approaches of how this is accomplished are briefly presented in this paper. This is followed by presenting some of the examples from the bioprocess development schemes, where the implementation of the methacrylate-based monolithic columns has resulted in a very efficient and productive process. Following this, we move back to the analytical scale and demonstrate the efficiency of the monolithic column--where the mass transfer between the stationary and mobile phase is greatly enhanced--for the in-process and final control of the new therapeutics. The combination of an efficient structure and the appropriate hardware results in separations of proteins with residence time less than 0.1 s.

Determining Surface Plasmon Resonance Response Factors for Deposition onto Three-Dimensional Surfaces

Intrinsic sorption rates of ligand/receptor binding have been measured by surface plasmon resonance (SPR) using response factors for deposition of proteins or smaller molecules on planar surfaces. In this study generalized expressions for SPR response factor and effective refractive index are developed to measure rates of analyte sorption onto 3-D surfaces. The expressions are specialized for two limiting cases of immediate practical interest and broad applicability: analyte deposition onto a homogeneous anisotropic porous media and deposition onto close-packed solid spheres adjacent to the sensor surface. These new equations specify media capacity, characteristic size and analyte concentration that are necessary to obtain identifiable responses from interaction with anisotropic porous media or chromatographic resin. These developments are illustrated by comparing response factors for Adenovirus Type 5 on planar surfaces, porous media and adsorptive spheres.

High-throughput analysis of mumps virus and the virus-specific monoclonal antibody on the arrays of a cationic polyelectrolyte with a spectral SPR biosensor

We investigated the potential use of a spectral surface plasmon resonance (SPR) biosensor in a high‐throughput analysis of mumps virus and a mumps virus‐specific mAb on the arrays of a cationic polyelectrolyte, poly(diallyldimethylammonium chloride) (PDDA). The PDDA surface was constructed by electrostatic adsorption of the polyelectrolyte onto a monolayer of 11‐mercaptoundecanoic acid (MUA). Poly‐l‐lysine was also adsorbed onto the MUA monolayer and compared with the PDDA surface in the capacity of mumps virus immobilization. The PDDA surface showed a higher adsorption of mumps virus than the poly‐l‐lysine surface. The SPR signal caused by the virus binding onto the PDDA surface was proportional to the concentration of mumps virus from 0.5 × 10⁵ to 14 × 10⁵ pfu/mL. The surface structure of the virus arrays was visualized by atomic force microscopy. Then, a dose‐dependent increase in the SPR signal was observed when various concentrations of the antimumps virus antibody in buffer or human serum were applied to the virus arrays, and their interaction was specific. Thus, it is likely that the spectral SPR biosensor based on the cationic polyelectrolyte surface may provide an efficient system for a high‐throughput analysis of intact virus and serodiagnosis of infectious diseases.