Rapid, accurate isolation and quantitation of viruses and virus-like particles

Isolate highly pure samples of viruses, virus-like particles, and viral vectors for diagnostics, monitoring therapeutic response, vaccine development, and gene therapy. Carry out multi-parameter measurements with single-particle resolution and unmatched precision. Evaluate viral titre or viremia with high accuracy in a matter of minutes.  

Izon’s unique system comprising qEV Isolation columns and Tunable Resistive Pulse Sensing (TRPS) analysis provides the only standardised method of isolating and quantifying virions and virus-like particles, and offers considerable advantages over other techniques in terms of speed, reproducibility, and simplicity. Measurement requires only 35 µL of sample and real-time analysis enables the assessment of sample aggregation over time.
virus particle
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Reliable isolation

Achieve reproducible separation of virus particles from extracellular vesicles, protein aggregates, and other contaminants.
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Accurate, real-time, label-free quantification

Directly quantify viral particles in liquid biopsy samples for diagnostic or monitoring purposes, or from cell culture as part of the production of viral vaccines
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Detection and identification of viruses

Distinguish between particles of different sizes with nanometre precision and discriminate between populations of particles with different surface properties with potential diagnostic applications.
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Reliable isolation

Isolation of viruses presents a challenge to virologists as many techniques cannot remove vesicles with similar properties or viral protein aggregates. Furthermore, most methods are based on nucleic acid extraction and thus involve destruction of the virus particle structure. Izon’s qEV Isolation columns enable fast and simple purification of virus particles with almost complete (>97%) removal of contaminating proteins, up to 60-fold enrichment of viral particles1 (Figure 1), and minimal need for equilibration and calibration. Contaminants, including free proteins and viral-protein aggregates, are efficiently removed, while the biophysical integrity of the particles of interest is retained. Particles are eluted into buffers suitable for downstream analyses in user-specified volumes. Viral particles can even be separated from extracellular vesicles that display viral proteins and nucleic acids, removing any ambiguity in research results and ensuring accurate quantification of the particle of interest. Combining qEV Isolation columns with Izon’s Automated Fraction Collector (AFC) creates a streamlined workflow and reduces inter- and intra-operator variability, improving reproducibility.
Figure 1.
The use of qEV Isolation columns enables purification of virions and virus particles with high purity. Pink and purple boxes indicate fractions that contain only exosomes (no viral particles) and only viral particles (no exosomes), respectively (Pleet et al.2).
Figure 2.
TRPS, NTA and MADLS measurements of quadrimodal sample  (CPN100/CPN150/CPN200/CPN240 at 1/1/1/1). TRPS, NTA and MADLS measurements were averaged over 3 runs. TRPS identifies all four sub populations clearly. NTA was able to identify that multiple sub populations were present. MADLS was not able to identify any sub populations.

Accurate quantification

Typical PCR-, antibody-, or infectivity-based analyses can be time consuming, complex, and low-throughput; TRPS analysis enables virus particles to be counted directly, avoiding the need for the multiple steps or the destruction of virus particles. Laborious optical techniques are not required and particles with different sizes, shapes, and surface properties can be quantified simultaneously with high accuracy and precision (Figure 2). As the only method of determining true particle concentration and size distribution, TRPS offers fast, accurate, and reproducible analysis and the semi-automated Exoid system enables high-throughput measurements to be carried out with high reproducibility and minimal intra-/inter-operator variability.

Detection and identification of viruses

The small size of virions presents a challenge to many characterisation methods, as discriminating between particles with very similar diameters within the nanorange can be difficult, if not impossible. The ability of TRPS to analyse heterogenous populations can enable identification of subpopulations of viruses within a sample when species exhibit different diameters or oligomeric states. Because all particles are detected, TRPS can characterise unknown or new viruses for which appropriate primers or antibodies have not been developed; a huge advantage and clinical necessity in the early stages of epi- or pandemics of new strains. Furthermore, changes in zeta potential or particle size in response to the binding of an antibody or detector molecule such as an aptamer can be evaluated using TRPS, which may enable the identification of viruses or specific quantification of subpopulations of virions within a mixed sample (Figure 3). Differences in the virion shape has been suggested to be a parameter which could enable discrimination between virus species. The ability of TRPS to differentiate between particles with different shapes has been demonstrated, which may enable identification and quantification of subpopulations of different viruses within a heterogenous sample.
Figure 3.
The Exoid is capable of measuring heterogenous samples over a wide size distribution, without the need for multiple measurements or adjustment of settings. Subpopulations can be identified with high resolution and accurately quantified individually.
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