BioProcessing Journal

Separation of Empty and Full Adeno-Associated Virus Capsids from a Weak Anion Exchanger by Elution with an Ascending pH Gradient at Low Ionic Strength

Separation of empty and full AAV8 capsids was achieved during their elution from a weak anion exchanger with an ascending pH gradient at low conductivity. Experimental data suggest elution was mediated by loss of positive charge from the exchanger. The method produced a full capsid peak with fewer empty capsids than elution of a strong anion exchanger with a salt gradient. Elution of the weak exchanger by sodium chloride gradients or by pH gradients in the presence of sodium chloride gave inferior separation performance. Pre-elution of empty capsids with a pH step allowed full capsids to be eluted by salt without compromising separation. Loading at intermediate pH prevented empty capsid binding and enabled step elution of full capsids in a physiological buffer environment.

Biologics Production

adeno-associated virus anion exchange chromatography ascending pH gradient elution elution separation

A Novel, Risk-based Approach for Predicting the Optimum Set of Process and Cell Culture Parameters for Scaling Upstream Bioprocessing

The ability to scale a cell culture effectively and efficiently, from lab to manufacturing, is critical to maximizing productivity whilst minimizing the risk of run failures and delays that can cost millions of dollars per month. The task of scaling well, however, is still considered to be a challenge by many upstream scientists, and this can be an exercise in trial and error. Traditionally, scaling has most often been performed using arithmetic in a spreadsheet and/or simple “back of an envelope” calculations. For some, it may even come in the form of support from a team of data scientists using advanced analytical software. This dependency on what some consider to be complex mathematics or statistics has resulted in the common consideration of using just one scaling parameter at a time, one scale at a time.

However, it is difficult to determine easily or optimally, from the start, whether a process successfully transfers across scales based on only one process parameter, at one scale. In this article, we describe the benefits of using a risk-based approach to scaling, and the development of a software scaling tool known as BioPAT® Process Insights for predictive scale conversion across different bioreactor scales. BioPAT Process Insights can be used to consider multiple parameters and across multiple scales simultaneously, from the start of a scaling workflow. We briefly describe how it was used in a proof-of-concept scale-up study to allow a faster, more cost-effective process transfer from 250 mL to 2000 L. In summary, using BioPAT Process Insights, in conjunction with a bioreactor range that has comparable geometry and physical similarities across scales, has the potential to help biopharma manufacturing facilities reach 2000 L production-scale volumes with fewer process transfer steps, saving both time and money during scale-up of biologics and vaccines.

Manufacturing Risk Analysis and Management

cell culture data analysis process optimization risk-based scaling scale-up software upstream processing

Monoclonal and Polyclonal Antibodies as Biological Reagents for SARS-CoV-2 Diagnosis Through Nucleocapsid Protein Detection

SARS-CoV-2 is an enveloped, positive-strand RNA virus that contains four structural proteins: spike, envelope, membrane, and nucleocapsid (N-protein). The N-protein participates in virus RNA packaging and particle release, is conserved within SARS-CoV-2 isolates, is highly immunogenic, and is abundantly expressed during SARS-CoV-2 infection. For these reasons, the N-protein could be used as a marker for detecting SARS-CoV-2 in early infection when antibodies against SARS-CoV-2 have not been produced yet. This paper describes the production and characterization of mouse monoclonal antibodies (mAb) and rabbit polyclonal antibodies (pAb) specific for the M20P19 peptide (N-protein linear epitope) for detection purposes. For this study, B-cell hybridomas were generated from mice independently immunized with two different M20P19 peptide-carrier protein conjugates: (1) meningococcal protein P64K; and (2) the keyhole limpet hemocyanin (KLH). Rabbits were also independently immunized with these two immunogens. Study results demonstrated that the M20P19 peptide was very immunogenic in mice and rabbits, and both mAb and pAb specifically recognized the non-conjugated M20P19 peptide, conjugated M20P19 peptide, and N-protein with high affinity and specificity, which could allow SARS-CoV-2 detection by different analytical techniques. This study corroborated that specific and high affinity constant mAb and pAb against the M20P19 peptide can be used as biological reagents for specific and rapid SARS-CoV-2 detection, mainly in tissue samples.

Biologics Production

diagnostics monoclonal antibody nucleocapsid protein detection polyclonal antibody serologic testing tissue sample pathology analysis

Demonstrating the Equivalence of Traditional Versus Automated Buffer Preparation Methods Using In-Line Conditioning Control Modes to Manage Incoming Stock Solution Variability

In-line conditioning (IC) is a form of dilution where a process buffer is formulated in-line from concentrated stock solutions of acids, bases, and salts that are mixed with the correct amount of water-for injection (WFI). This new buffer preparation strategy must prove its equivalency to buffers made the traditional way (i.e., weighing salts, stirring in water, titrating with acid or base). In this paper, such a demonstration is presented using two control modes: (1) ratio control with flow feedback; and (2) pH/conductivity feedback. To obtain the necessary parameters for an error propagation analysis, a robustness study has been performed. Our analysis showed that with low incoming variability, or when the uncertainty of the stock solutions is below 2%, the two modes of control give comparable performance. When the uncertainty increases, so does the uncertainty of ratio control with flow feedback, more with respect to conductivity than pH, while the precision of pH/conductivity feedback remains at the same level. The choice of control should therefore take into consideration the critical process parameters, their tolerances, and the input variability in the stock solution concentration. In situations where there are higher variabilities in stock solution concentrations or process temperatures, this study suggests that pH/conductivity feedback might be a better option.

Biologics Production

buffer management critical process parameters in-line conditioning point-of-use process buffer purification variability

Seed Train Process Intensification Strategy Offers Potential for Rapid, Cost-Effective Scale-Up of Biosimilars Manufacturing

A perfusion approach at N-1, where cells stay in the exponential growth phase throughout the entire culture duration, is becoming more common as a strategy for process intensification. This is because the higher cell densities it generates allows manufacturers to skip seed stages and reduce process transfer time through multiple bioreactor sizes, thus providing more cost-effective biologics production in smaller facilities. However, this N-1 perfusion approach requires optimization. In this article, we describe the development and proof-of-concept studies with single-use rocking motion perfusion bioreactors in which we have achieved a ten-fold increase in viable cell count in N-1 seed stage, compared to the fed-batch control process, in just 6–8 days. We also mention in detail how we inoculated a 50 L bioreactor production run using this intensified seed train and show comparable growth kinetics and yield with a control process, also at 50 L scale. Using this intensification approach in the future will help our manufacturing facility, the Biopharma Division of Intas Pharmaceuticals Ltd., reach 4000 L production-scale volumes with fewer process transfer steps, and without changing the feeding strategy or production bioreactors of our biologics’ portfolio.

Manufacturing

continuous perfusion process intensification rocking motion perfusion bioreactor scale-up seed train single-use bioreactor upstream processing

Design and Performance of Viral Clearance Studies with Tissue-Derived Products

Tissue-derived products are a class of biological materials harvested directly from animal or human tissue, in contrast to recombinant DNA materials grown in cell culture bioreactors. Tissue-derived products are often used for structural purposes and are typically regulated as medical devices. However, when used to treat human patients, tissue-derived products are subject to many of the same concerns as recombinant DNA biotherapeutics, with viral safety being one of them. To address this, the tissue source material must undergo a risk analysis and testing regimen for the presence of viral contaminants. In addition, viral clearance studies must be performed to evaluate whether the purification process is robust enough to remove and/or inactivate viruses that may be present in the starting material.

The goals of viral clearance studies are the same for tissue-derived products and biotherapeutics, but the design and performance of these studies can be quite different because of the diverse nature of the materials. In this article, we will present an overview of viral clearance studies for tissue-derived products based on our experience in performing a large number of such studies. Rather than discussing the issues related to viral clearance in general, our focus will be on the unique challenges that tissue-derived products pose.

Biologics Production Regulatory Risk Analysis and Management

contaminant control purification tissue-derived products viral clearance viral clearance study viral safety

A Direct Method to Monitor Glutathione Stability in High Concentration Protein Formulations

Due to its antioxidant properties and favorable safety profile, glutathione (GSH) finds use in protein formulations by improving overall protein stability. Once degraded, primarily by oxidation into glutathione disulfide (GSSG), the protecting effect of GSH is lost. A simple, direct method using reversed-phase separation and charged-aerosol detection (RP-CAD) to quantitate GSH is described in this paper. The analytical methodology is also capable of monitoring several by-product degradants of GSH, both oxidative and non-oxidative. For high-concentration protein formulations, the method provides direct analysis of GSH and its degradants in the presence of protein at up to 225 mg/mL simply through a dilution of the sample. Quantitation of many amino acids typically included in pharmaceutical protein formulations is also possible. Use of an online diverting valve in the method prevents interference in the detector from the high protein concentration in formulation. Accuracy and effectiveness of this method is demonstrated through monitoring the stability of GSH in high-concentration protein formulations through confirmation of GSH concentration and mass-balance of its loss over time. Monitoring GSH stability in protein formulations is necessary, as GSH concentration is indicative of protein stability.

Biologics Production

charged-aerosol detection glutathione stability reversed-phase chromatography stability

Defining Therapeutic Window for Viral Vectors: A Statistical Framework to Improve Consistency in Assigning Product Dose Values

NOTE: Page 7 of this article has been revised to correct an error in the original article which stated that “…the probability of failing a lot when it actually is not equivalent, becomes 1-2*α.” The correct equation, 1-α, has replaced the errant one and a single sentence following it was added to further clarify this concept.

ABSTRACT: Pre-clinical and clinical trials conducted to establish the minimum effective dose and the maximum tolerated dose of a viral vector assume that the assigned dose values are comparable across studies. Toxicity has been associated with high dose administration of both adenovirus and adeno-associated virus-based vectors, and increased attention must be paid to assays used to measure dose. High assay variability can be mitigated by replication and the reporting of a mean value for product lot release. The establishment of a dose specification and a testing strategy must take into account the risk of errant quality control decisions. This can be accomplished by linking assay qualification information to measurement uncertainty through a statistical framework. By adopting an equivalence approach, the risk of releasing lots with unacceptably high or low dose values is minimized by reducing measurement uncertainty. This article provides a worked-through example to introduce applicable statistical concepts and the equations necessary to facilitate their implementation in the field.

Risk Analysis and Management Viral Vectors

adeno-associated viral vectors adenoviral vectors assay qualification dosage dose-determining assay equivalence limits therapeutic window

Alcohol Determination in Protein Fractionation Intermediates by Steam Distillation and Digital Refractometry

Almost 75 years after implementing the industrial ethanol fractionation process, based on the pioneering work of Edwin J. Cohn’s research group, this niche biotechnology process has not lost its importance in helping to supply patients with life-saving biotherapies. Clearly, the focus has shifted from albumin, which was first used, to the indispensable immunoglobulin preparations produced for the effective, long-term treatment of patients suffering from immunodeficiencies. In addition, the widespread and safe therapeutic use of immunoglobulins has paved the way for the development of monoclonal antibodies, now used not only for the treatment of various autoimmune diseases, but also for cancer treatment. The Cohn fractionation process, based on the different solubilities of plasma proteins, depends on the five parameters of ethanol concentration, pH, temperature, protein, and salt concentration, which are the basis of this development. Ethanol concentration can clearly be considered an essential critical parameter for this process. Therefore, it is surprising that even after the advent of process analytical technology, there is still no fast, precise, and accurate procedure at hand to determine the alcohol content of Cohn fractionation intermediates. In this paper, we will describe the implementation of an old methodology for a new purpose, which is designed to close this gap.

Biologics Production

alcohol precipitation digital refractometry gravimetric sample dosage protein fractionation steam distillation

Porcine Serum, Trypsin, and Other Porcine-Derived Products: Swine Viruses of Importation and Adventitious Concern

The rapid and seemingly uncontrolled spread of African swine fever (ASF) throughout China and many of its neighboring countries within the last 19 months (August 2018–March 2020) has put the rest of the world on high alert. The geographic distribution of viruses of importation concern, like ASF virus (ASFV), can change very quickly, putting at risk conventional sources of porcine serum and other porcine-derived products used as ingredients in research, the manufacture of biologics, and other biomedical applications. This article reviews the 2019 information from the World Organization for Animal Health (OIE) regarding the presence or absence of eight viruses of importation concern in the swine populations of 30 countries from animal serum-producing regions of the world. Companies importing porcine raw materials for formulation into porcine products – and their customers – should be aware of the geographic location of swine diseases of importation concern. The article also identifies ten adventitious viruses of concern cited in United States Department of Agriculture (USDA) and European Union (EU) regulations that need to be tested for or eliminated through one or more barrier treatments when porcine ingredients are used in the manufacture of biologics.

Biologics Production Risk Analysis and Management

adventitious agents adventitious virus porcine serum porcine-derived products trypsin

BioProcessing Journal Posts

SEARCH