Capillary electrophoresis with postcolumn infectivity assay for the analysis of different serotypes of human rhinovirus (common cold virus)

On-line separation and quantification of virus antigens of different serotypes in multivalent vaccines by capillary zone electrophoresis: A case study for quality control of foot-and-mouth disease virus vaccines

Accurate quantification of effective antigens of different serotypes is crucial for quality control of multivalent vaccines but challenging. A simple and rapid capillary zone electrophoresis (CZE) method was developed for on-line separation and quantification of foot-and-mouth disease virus (FMDV) antigens in monovalent and bivalent FMDV vaccines. The FMDV peak identity in CZE was demonstrated by the study of FMDV dissociation combined with high performance size exclusion chromatography (HPSEC) analysis. After optimizing CZE conditions including UV detecting wavelength, injection volume, and separation voltage, both serotype A and O FMDV showed good reproducibility (RSD <5%) and linear responses (R²=0.999) between the peak area and FMDV content in the concentration range of 15-400 μg/mL. The two serotypes of FMDV with similar size had different migration time in CZE according to their different zeta potential, which allows them to be separated and quantified, with accuracy of <10% relative error. CZE was then successfully applied for antigen quantification of commercial O monovalent and A/O bivalent FMDV vaccines. Compared with HPSEC, CZE was not only able to quantify each serotype of FMDV, but also free from interference of nucleic acids impurities. In summary, the CZE can be a simple, rapid, and reliable tool for quality control of monovalent and bivalent FMDV vaccines. The CZE method can also be further extended to the quality control of other multivalent virus and virus like particle vaccines.

Characterization and stabilization in process development and product formulation for super large proteinaceous particles

Super large proteinaceous particles (SLPPs) such as virus, virus like particles, and extracellular vesicles have successful and promising applications in vaccination, gene therapy, and cancer treatment. The unstable nature, the complex particulate structure and composition are challenges for their manufacturing and applications. Rational design of the processing should be built on the basis of fully understanding the characteristics of these bio-particles. This review highlights useful analytical techniques for characterization and stabilization of SLPPs in the process development and product formulations, including high performance size exclusion chromatography, multi-angle laser light scattering, asymmetrical flow field-flow fractionation, nanoparticle tracking analysis, CZE, differential scanning calorimetry, differential scanning fluorescence, isothermal titration calorimetry , and dual polarization interferometry. These advanced analytical techniques will be helpful in obtaining deep insight into the mechanism related to denaturation of SLPPs, and more importantly, in seeking solutions to preserve their biological functions against deactivation or denaturation. Combination of different physicochemical techniques, and correlation with in vitro or in vivo biological activity analyses, are considered to be the future trend of development in order to guarantee a high quality, safety, and efficacy of SLPPs.

Modern Approach to Medical Diagnostics - the Use of Separation Techniques in Microorganisms Detection

Background:

Analytical chemistry and biotechnology as an interdisciplinary fields of science have been developed during many years and are experiencing significant growth, to cover a wide range of microorganisms separation techniques and methods, utilized for medical therapeutic and diagnostic purposes. Currently scientific reports contribute by introducing electrophoretical and immunological methods and formation of devices applied in food protection (avoiding epidemiological diseases) and healthcare (safety ensuring in hospitals).

Methods:

Electrophoretic as well as nucleic-acid-based or specific immunological methods have contributed tremendously to the advance of analyses in recent three decades, particularly in relation to bacteria, viruses and fungi identifications, especially in medical in vitro diagnostics, as well as in environmental or food protection.

Results:

The paper presents the pathogen detection competitiveness of these methods against conventional ones, which are still too time consuming and also labor intensive. The review is presented in several parts following the current trends in improved pathogens separation and detection methods and their subsequent use in medical diagnosis.

Discussion:

Part one, consists of elemental knowledge about microorganisms as an introduction to their characterization: descriptions of divisions, sizes, membranes (cells) components. Second section includes the development, new technological and practical solution descriptions used in electrophoretical procedures during microbes analyses, with special attention paid to bio-samples analyses like blood, urine, lymph or wastewater. Third part covers biomolecular areas that have created a basis needed to identify the progress, limitations and challenges of nucleic-acid-based and immunological techniques discussed to emphasize the advantages of new separative techniques in selective fractionating of microorganisms.

Thermodynamics of antimicrobial peptide JCpep8 binding to living Staphylococcus aureus as a pseudo-stationary phase in capillary electrochromatography and consequences for antimicrobial activity

To understand the details of the permeation pathways of antimicrobial peptide JCpep8, the antimicrobial processes were investigated step by step in this paper. First, the characterization of the initial binding process was explored by introducing the living Staphylococcus aureus cells (LSACs) into electrophoretic buffer used as pseudo-stationary phase in capillary electrochromatography (CEC), and the thermodynamic parameters were determined. The binding constants at 298, 303, and 309 K were 7.40 × 10¹¹, 1.43 × 10¹², and 2.6 × 10¹² M⁻¹, respectively, which indicated the evident interaction between JCpep8 and LSACs. This binding process was spontaneous. Both the electrostatic force and hydrophobic effect play major roles in this binding process. Second, antibacterial activity kinetics and outer membrane and inner membrane disruption assays were investigated. Data indicated that JCpep8 killed microbes principally by breaking their cell wall and membrane, followed by cell lysis. The results were confirmed by Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). In summary, JCpep8 kills microbes mainly by wall-/membrane-targeting pore-forming mechanisms.

Separation of rotavirus double-layered particles and triple-layered particles by capillary zone electrophoresis

Cell culture derived rotavirus preparations contain a mixture of double-layered particles (DLPs) and triple-layered particles (TLPs). Characterization of rotavirus vaccine products is important to demonstrate a consistent manufacturing process. A capillary zone electrophoresis (CZE) method was developed to separate and quantitate rotavirus DLPs and TLPs in cell lysate samples and CsCl-purified vaccine preparations of each of the five reassortant rotavirus vaccine strains (G1, G2, G3, G4 and P1) contained in the pentavalent rotavirus vaccine, RotaTeq. The CZE electropherograms showed that migration of DLPs and TLPs from both CsCl-purified and cell lysates resulted in a separation distance of approximately 3 min between the two rotavirus particle types. The identification of the peak(s) containing TLPs was confirmed for both CsCl-purified and cell lysate samples by treatment of the samples with 50mM EDTA, which converted TLPs to DLPs. The migration pattern of the DLPs was consistent (23-24 min) among all reassortant strains tested, whether the DLPs were CsCl-purified or from cell lysates. However, the migration pattern of the TLP electropherograms of the reassortant rotavirus strains in cell lysates differed from those of the CsCl-purified reassortant rotavirus strains. In the cell lysate samples, the TLPs of the G1 and G2 reassortant rotavirus strains migrated slower that the corresponding TLPs from the CsCl-purified samples, while the migration time of the TLPs of the G3, G4 and P1 reassortants strains from the cell lysate and CsCl-purified samples appeared similar. Also, the TLPs from the CsCl-purified samples appeared as a defined single peak, while most of the TLPs from the cell lysate samples appeared as a broad peak or as multiple peaks. All the migration patterns were reproducible and consistent. Taking into account reproducibility, objective quantitation, and minimal sample manipulation as well as volume, CZE allowed consistent and quantitative characterization of rotavirus vaccine preparations, which is required for evaluation of vaccine products, including process validation.

Virus analysis using electromigration techniques

We discuss the progress during the last 4 years in the analysis of viruses by electrophoresis in capillaries and microfluidic devices. The paper is the continuation of a review published in this journal in 2005 [Kremser, L., Blaas, D., Kenndler, E., Electrophoresis 2004, 25, 2282-2291]. Eighteen papers on the topic have appeared since; the majority deals with zone electrophoresis and three reports are on IEF. These methods have been applied to human rhinoviruses, poliovirus Semliki Forest virus, norovirus-like particles, and the two bacteriophages MS2 and T5. A main finding was that addition of detergents and salts to the BGEs are essential for the robustness of the CE analysis. Analyte detection was usually via UV absorbance but there are some examples where the viruses were rendered fluorescent via modification of the capsid proteins with reactive dyes and/or by non-covalent attachment of intercalating fluorescent compounds to the nucleic acids making up the viral genome. Interestingly, some viruses are permeable to small molecular mass components; this allows fluorescent dyes to diffuse into the intact virus where they attach to the nucleic acid. Release of a viral genome upon heating was also monitored by using similar methodologies. Interactions of viruses and subviral particles with antibodies, receptors, and receptor-decorated liposomes were investigated with CE methods, all by using a non-equilibrium approach (i.e. co-incubation of the components prior to CE separation). Viruses are multivalent (i.e. possess many identical surface-exposed patches) and most of them are composed of defined numbers of identical subunits. The high resolution of CE has been most remarkably demonstrated by the separation of stoichiometric complexes between virus and a distinct number of soluble recombinant receptors and revealed their concentration-dependent distribution.

Capillary electrophoresis separation of microorganisms

Microorganisms can be considered a bio-colloid. That is, they have a characteristic outer surface that carries, or can carry, a charge. Precisely, differences in the surface can be exploited for separation by capillary electrophoresis (CE). In fact, methods based on CE seem to be very promising because they should produce rapid and high-efficiency separations. Although CE can be used to separate microbial (i.e., bacteria, virus, fungi, and whole cells) and subcellular particles (i.e., mitochondria and nuclei), this chapter is focused mainly on the determination of bacteria and virus for their interest. At difference to the separation off molecules, microorganisms are characterized as living. This makes their analysis more difficult because several aspects such as possible lysis, aggregation, evolution, growing etc. must be taken into count.

Electrophoresis on a microfluidic chip for analysis of fluorescence-labeled human rhinovirus

We report the analysis of human rhinovirus serotype 2 (HRV2) on a commercially available lab-on-a-chip instrument. Due to lack of sufficient native fluorescence, the proteinaceous capsid of HRV2 was labeled with Cy5 for detection by the red laser (lambda ex 630 nm) implemented in the instrument. On the microdevice, electrophoresis of the labeled virus was possible in a BGE without stabilizing detergents, which is in contrast to conventional CE; moreover, analysis times were drastically shortened to the few 10 s range. Resolution of the sample constituents (virions, a contaminant present in all virus preparations, and excess dye) was improved upon adaptation of the separation conditions, mainly by adjusting the SDS concentration of the BGE. Purity of fractions from size-exclusion chromatography after labeling of virus was assessed, and affinity complex formation of the labeled virus with various recombinant very-low-density lipoprotein receptor derivatives differing in the number of concatenated V3 ligand binding repeats was monitored. Virus analysis on microchip devices is of particular interest for experiments with infectious material because of easy containment and disposal of samples. Thus, the employment of microchip devices in routine analysis of viruses appears to be exceptionally attractive.

Capillary electrophoresis of viruses, subviral particles and virus complexes

CZE and CIEF were so far applied to the analysis of tobacco mosaic virus, Semliki forest virus, human rhinovirus, adenovirus, norovirus and the bacteriophages T5 and MS2. The concentration of viral or subviral particles, of capsid proteins and viral genomes were determined, their electrophoretic mobilities and pI values were measured and bioaffinity reactions between viruses and antibodies, antibody fragments and receptor fragments were assessed. The role of detergents added to the BGE to obtain reproducible electrophoretic conditions was elucidated. The analytes were detected via their UV-absorbance or via fluorescence after derivatization of the viral capsid, the nucleic acid, or both. A new dimension to the detection is added by the possibility of making use of the viral infectivity. At least in theory, this allows for the unequivocal identification of a single infectious virus particle after collection at the capillary outlet. This review summarizes the 25 papers so far published on this topic.

Capillary electrophoresis of affinity complexes between subviral 80S particles of human rhinovirus and monoclonal antibody 2G2

Human rhinoviruses (HRVs), the main etiologic agents of the common cold, transform into subviral B- or 80S particles (they sediment at 80S upon sucrose density gradient centrifugation) during infection and, in vitro, upon exposure to a temperature between 50 and 56 degrees C. With respect to the native virion they lack the genomic RNA and the viral capsid protein VP4. 80S particles are unstable and easily disintegrate into their components, VP1, VP2, and VP3 in buffers containing SDS. However, this detergent was found to be a necessary constituent of the BGE for the analysis of these viruses and their complexes with receptors and antibodies by CE. We here demonstrate that dodecylpoly(ethyleneglycol ether) (D-PEG) a nonionic detergent, is suitable for analysis of subviral particles as it preserves their integrity, in contrast to SDS. Electrophoresis of the 80S particles in borate buffer (pH 8.3, 100 mM) containing 10 mM D-PEG resulted in a well-defined electrophoretic peak. The identity of the peak was confirmed, among other means, by complexation with mAb 2G2, which recognizes a structural epitope exclusively present on subviral particles but not on native virus. Upon incubation of the 80S particles with mAb 2G2 the peak disappeared, but a new peak, attributed to the antibody complex emerged. The separation system allowed following the time course of the transformation of intact HRV serotype 2 into 80S particles upon incubation at temperatures between 40 and 65 degrees C. We also demonstrate that subviral particles derived from HRV2 labeled with the fluorescence dyes FITC or Cy3.5 were stable in the separation system containing D-PEG. Dye-modified particles were still recognized by mAb 2G2, suggesting that the exposed lysines that are derivatized by the reagent do not form part of the epitope of the antibody.

Influence of detergent additives on mobility of native and subviral rhinovirus particles in capillary electrophoresis

The electrophoretic properties of two human rhinovirus (HRV) serotypes, HRV2 and HRV14, their subviral particles, and their capsid proteins were investigated by CE using borate buffer, pH 8.3, as BGE and three different detergents as additives. In addition, the influence of modification of the capsid with an amine reactive fluorescent dye, Cy3.5, on migration in the electric field was assessed. We found that the reproducibility of the electrophoretic results was decisively dependent on the presence of the detergents above their respective CMC. As compared to the strong ionic detergent SDS, the nonionic, mild detergent dodecylpoly(ethyleneglycol ether) (D-PEG) efficiently and reproducibly resolved both, native viruses as well as subviral particles. Most of the analytes behaved as expected except native HRV2; this serotype showed a dramatically higher anionic mobility in SDS than in D-PEG. Additionally, its mobility decreased when each positive charge contributed from a lysine at the capsid surface was substituted by four negative charges upon derivatization with Cy3.5. We discuss the possibility that this effect is caused by differences in number and in arrangement of exposed lysines in the two serotypes leading to differences in the amount of bound SDS micelles.

The influence of ionic strength on the interaction of viruses with charged surfaces under environmental conditions

The influence of ionic strength on the electrostatic interaction of viruses with environmentally relevant surfaces was determined for three viruses, MS2, Q beta, and Norwalk. The virus is modeled as a particle comprised of ionizable amino acid residues in a shell surrounding a spherical RNA core of negative charge, these charges being compensated for by a Coulomb screening due to intercalated ions. A second model of the virus involving surface charges only is included for comparison. Surface potential calculations for each of the viruses show excellent agreement with electrophoretic mobility and zeta potential measurements as a function of pH. The environmental surface is modeled as a homogeneous plane held at constant potential with and without a finite region (patch) of opposite potential. The results indicate that the electrostatic interaction between the virus and the oppositely charged patch is significantly influenced by the conditions of ionic strength, pH and size of the patch. Specifically, at pH 7, the Norwalk virus interacts more strongly with the patch than MS2 (approximately 51 vs approximately 9kT) but at pH 5, the Norwalk-surface interaction is negligible while that of MS2 is approximately 5.9kT. The resulting ramifications for the use of MS2 as a surrogate for Norwalk are discussed.

Behaviors of the MS2 virus and related antibodies in capillary isoelectric focusing with whole-column imaging detection

Capillary isoelectric focusing (CIEF) has potential importance for the study of viruses. CIEF with whole-column imaging detection (WCID) is a novel CIEF mode, providing the advantages of high resolution, high speed, and easy method development. To facilitate the application of CIEF-WCID to the immunoassay of viruses, a basic knowledge of related aspects is necessary. In this study, the MS2 bacteriophage was used as a virus model, and the behaviors of MS2 and related antibodies in CIEF were investigated with UV absorbance-WCID and laser-induced fluorescence (LIF)-WCID. The adsorption of the virus and antibodies on the capillary wall was found to be the critical issue in method development. Addition of salt was found to be an effective way to reduce the adsorption and to improve peak shape. The formation of an immunocomplex, which forms the basis of an immunoassay, was monitored with CIEF-WCID. In comparison with UV-WCID, LIF-WCID was advantageous due to its higher detection sensitivity and the elimination of precipitation. Utilization of the noncovalent fluorescent dye, NanoOrange, was demonstrated to be a potential approach for the fluorescent labeling of the virus model and antibody and the associated immunocomplex. The change in microheterogeneity during the immune interactions at different ratios was also observed.

Twelve receptor molecules attach per viral particle of human rhinovirus serotype 2 via multiple modules

The crystallographic T = 1 (pseudo T = 3) icosahedral symmetry of the human rhinovirus capsid dictates the presence of 60 identical, symmetry related surface structures that are available for antibody and receptor binding. X-ray crystallography has shown that 60 individual very-low density lipoprotein receptor (VLDLR) modules bind to HRV2. Their arrangement around the fivefold axes of the virion suggested that tandem oligomers of such modules could attach simultaneously to symmetry-related sites. By resolving virus particles carrying various numbers of artificial recombinant concatemers of VLDLR repeat 3 (V33333) by capillary electrophoresis and extrapolation of the measured mobilities to that at saturation of all binding sites, we present evidence for up to 12 molecules of the concatemer to bind one single virion.

Separation and analysis of colloidal/nano-particles including microorganisms by capillary electrophoresis: a fundamental review

A review is presented on the CE analysis of colloidal/nano particles. Topics discussed include the CE separation of polymeric, inorganic, microbial (i.e. viruses, bacteria, fungi, and whole cells), and sub-cellular particles (i.e. mitochondria and nuclei). Several of the encountered difficulties in analysis are presented as well as the methods employed to overcome them.