Development of a targeted nanoLC-MS/MS method for quantitation of residual toxins from Bordetella pertussis

A highly sensitive method for determination of tacrolimus in peripheral blood mononuclear cells by nano liquid chromatography-high resolution accurate mass spectrometry

The determination of intracellular tacrolimus concentration in peripheral blood mononuclear cells (PBMCs) is crucial for assessing the effect-site concentration of tacrolimus. Analytical methods previously reported required a minimum of 3 mL of whole blood sample for measuring the tacrolimus concentration. In this study, we developed a highly sensitive method using EASY nLC 1200 combined with Q Exactive orbitrap mass spectrometer for detecting tacrolimus in PBMCs, requiring only 0.5-2 mL of sample. Furthermore, we compared two primary normalization methods for PBMCs tacrolimus concentration using Passing-Bablok regression, Bland-Altman analysis, Spearman's rank correlation, and Mountain plot. The newly established method was employed to compare tacrolimus concentrations in whole blood and PBMCs among 194 lung transplant recipients. The developed method exhibited high sensitivity with a lower limit of quantitation at 5 pg/mL, and excellent intra- and inter-days accuracy and precision. The comparison between different normalization methods for PBMCs tacrolimus concentration revealed a strong correlation between PBMCs count and intracellular protein amount within these cells. This finding suggests that both PBMCs count and intracellular protein amount can be used for normalizing intracellular tacrolimus levels and can be mutually converted. However, a weaker correlation was observed between PBMCs and whole-blood tacrolimus concentrations in lung transplant recipients, warranting further investigation. The method reported herein enables the quantification of PBMCs tacrolimus concentration using smaller volumes of whole blood samples, which has significant implications for both patients and laboratory personnel.

A Strategy for Rapid Discovery of Marker Peptides Associated with Fibrinolytic Efficacy of Pheretima aspergillum Based on Bioinformatics Combined with Parallel Reaction Monitoring

Quality control of animal-derived traditional Chinese medicines has improved dramatically as proteomics research advanced in the past few decades. However, it remains challenging to identify quality attributes with routine proteomics approaches since protein with fibrinolytic activity is rarely reported in pheretima, a typical animal-derived traditional medicine. A novel strategy based on bioinformatics combined with parallel reaction monitoring (PRM) was developed here to rapidly discover the marker peptides associated with a fibrinolytic effect. Potential marker peptides were found by lumbrokinase sequences’ alignment and in silico digestion. The fibrinogen zymography was used to visually identify fibrinolytic proteins in pheretima. As a result, it was found that the fibrinolytic activity varied among different portions of pheretima. Fibrinolytic proteins were distributed regionally in the anterior and anterior-mid portion and there was no significant fibrinogenolytic activity observed in the mid-posterior and posterior portion. Finally, PRM experiments were deployed to validate and quantify selected marker peptides and a total of 11 peptides were identified as marker peptides, which could be potentially used in quality control of pheretima. This strategy provides a robust workflow to benefit the quality control of other animal-derived traditional medicines.

Design of a Quantitative LC-MS Method for Residual Toxins Adenylate Cyclase Toxin (ACT), Dermonecrotic Toxin (DNT) and Tracheal Cytotoxin (TCT) in Bordetella pertussis Vaccines

The antigens for acellular pertussis vaccines are made up of protein components that are purified directly from Bordetella pertussis (B. pertussis) bacterial fermentation. As such, there are additional B. pertussis toxins that must be monitored as residuals during process optimization. This paper describes a liquid chromatography mass spectrometry (LC-MS) method for simultaneous analysis of residual protein toxins adenylate cyclase toxin (ACT) and dermonecrotic toxin (DNT), as well as a small molecule glycopeptide, tracheal cytotoxin (TCT) in a Pertussis toxin vaccine antigen. A targeted LC-MS technique called multiple reaction monitoring (MRM) is used for quantitation of ACT and TCT, which have established limits in drug product formulations. However, DNT is currently monitored in an animal test, which does not have an established quantitative threshold. New approaches for DNT testing are discussed, including a novel standard based on concatenated quantitation sequences for ACT and DNT. Collectively, the method represents a “3-in-1” analytical simplification for monitoring process-related residuals during development of B. pertussis vaccines.

Overcoming scientific barriers in the transition from in vivo to non-animal batch testing of human and veterinary vaccines

INTRODUCTION

Before release, vaccine batches are assessed for quality to evaluate whether they meet the product specifications. Vaccine batch tests, in particular of inactivated and toxoid vaccines, still largely rely on in vivo methods. Improved vaccine production processes, ethical concerns, and suboptimal performance of some in vivo tests have led to the development of in vitro alternatives.

AREAS COVERED

This review describes the scientific constraints that need to be overcome for replacement of in vivo batch tests, as well as potential solutions. Topics include the critical quality attributes of vaccines that require testing, the use of cell-based assays to mimic aspects of in vivo vaccine-induced immune responses, how difficulties with testing adjuvanted vaccines in vitro can be overcome, the use of altered batches to validate new in vitro test methods, and how cooperation between different stakeholders is key to moving the transition forward.

EXPERT OPINION

For safety testing, many in vitro alternatives are already available or at an advanced level of development. For potency testing, in vitro alternatives largely comprise immunochemical methods that assess several, but not all critical vaccine properties. One-to-one replacement by in vitro alternatives is not always possible and a combination of methods may be required.

Biopharmaceutical quality control with mass spectrometry

Mass spectrometry (MS) is a powerful technique for protein identification, quantification and characterization that is widely applied in biochemical studies, and which can provide data on the quantity, structural integrity and post-translational modifications of proteins. It is therefore a versatile and widely used analytic tool for quality control of biopharmaceuticals, especially in quantifying host-cell protein impurities, identifying post-translation modifications and structural characterization of biopharmaceutical proteins. Here, we summarize recent advances in MS-based analyses of these key quality attributes of the biopharmaceutical development and manufacturing processes.

Quantitative microcapillary electrophoresis immunoassay (mCE IA) for end-to-end analysis of pertactin within in-process samples and Quadracel® vaccine

Protein concentration is an important attribute in the production of subunit or component-based vaccine antigens. Rigorous monitoring of protein concentration is required to identify potential areas for yield improvement. The current GMP method for quantitation is the plate-based ELISA which requires numerous hands-on steps and has low sensitivity in comparison to new microfluidic systems. To address this issue, a sensitive automated microCapillary Electrophoresis ImmunoAssay (mCE IA) method was developed to accurately separate and quantitate pertactin (PRN), an important antigen of the modern acellular Pertussis (aP) vaccine. PRN is reported to be a low-yielding antigen; thus, it is critical to observe its concentration throughout its manufacturing process. First, a primary antibody for PRN was identified to establish suitable immunoprobing conditions for detection of PRN over a wide linear dynamic range that spans 3 orders of magnitude. Next, the pre-adsorbed PRN Drug Substance (DS) was used as a reference standard to quantitate PRN samples against a calibration curve with adequate accuracy and precision. Four representative samples including three in-process steps and final adjuvanted drug product: Quadracel®, were examined to demonstrate the capability of mCE IA to quantitate PRN with high sensitivity and specificity. The matrices of the selected samples contain additional components (e.g. other proteins, growth factors, cell culture media, residual ammonium sulfate, and aluminum adjuvant) often making the quantitation of PRN challenging. The specificity and method linearity were demonstrated by spiking pre-adsorbed PRN DS into the four representative samples. In addition, it was shown that reportable concentrations of PRN for nine downstream process steps as analyzed by our method is comparable to concentrations obtained with ELISA. Most importantly, this study demonstrated that our method's quantitative accuracy is independent of matrix components, as each sample undergoes extensive dilution. This allows for seamless end-to-end analysis of PRN from fermenter harvest, through to complex downstream process samples to adjuvanted drug products. Finally, for the first time the developed and qualified mCE IA method was shown to quantify PRN throughout the entire manufacturing process to provide rapid feedback for process optimizations allowing for accurate yield and step-loss calculations.