Virus Titration and Quantification

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Virus Titration and Quantification

Method Introduction

Coriolis Pharma offers a variety of methods to obtain virus titers. One option is determining how many virus particles per volume are inside a sample (i.e., the physical titer). This is done using particle characterization techniques – you can read more about that here. However, such techniques may only tell part of the story because the infectious or functional titer (i.e., how much virus can infect the target cell) is usually more important and meaningful and may not directly correlate to the number of virus particles in a sample.

  • The number of infectious virus particles is frequently quantified using the Median Tissue Culture Infectious Dose (TCID50) assay. The assay works by adding a serial dilution of the virus sample to cells in a 96-well plate format. The type of cell is specifically selected to show a cytopathic effect (CPE), i.e., morphological changes upon infection with the virus or cell death. After an incubation period, the cells are inspected for CPE or cell death, and each well is classified as infected or not infected. Colorimetric or fluorometric readouts are also possible, which can increase assay sensitivity. The dilution, at which 50% of the wells show a CPE, is used to calculate the TCID50 of the virus sample. This calculation can generally be done using a variety of mathematical approaches, e.g., the Spearman-Karber method or the Reed-Muench method. Virus titer is expressed as TCID50 / ml.

  • Depending on the virus, the type of cells, and the readout parameter indicating an infection, a variety of other virus titration assays are possible. A plaque-forming assay is commonly employed to quantify viruses that lyse the infected cell. The virus sample is added (in a suitable dilution) to a monolayer-forming cell culture and incubated over several days. Areas with infected cells will be visible as holes or plaques by microscopy or colorimetric or fluorometric staining. Virus quantity is expressed as infectious units (IFU) / ml or plaque-forming units (PFU) / ml.

Applications

Virus titration is integral to developing, manufacturing, and quality control of virus products, including advanced therapy medicinal products (ATMPs).

Our Services for Virus Quanitifcation:

  • Transfer, implementation and application of existing TCID50 assays
  • Transfer, implementation and application of existing plaque-forming assays
  • Development of tailor-made virus titration/quantification assays

Quality and Biosafety Level

We provide all our analytical services with the highest quality standards. Experienced scientists carry out each project, and a scientific reviewer comprehensively checks every report or data presentation.

We offer this technology with the following quality and biosafety levels:

R&D level

We offer this method under R&D. Our GRP system assures the highest-quality research standards.

Up to biosafety level 2

This method can be applied to nucleic acids, viruses, cells, viral vectors, including lentiviruses and more.

Analytical Method Development, Qualification and Validation

For common sample types, we can often apply standardized methods with little setup effort. However, when needed, our experienced analytical experts create or optimize custom methods tailored to your active pharmaceutical ingredient, product type and development phase.

Method Development

Our method development approach tailors sample preparation, method settings and data analysis to the needs of your project and sample.

We include representative samples and, where available, suitable reference standards and stressed/degraded materials, allowing our analytical scientists to design a highly suitable, stability-indicating, robust and repeatable method. Upon request, we will compile a detailed description of the method for your records.

Method Qualification

Method qualification is the initial assessment of an analytical procedure’s performance to show its suitability for its intended purpose.

During method qualification, our analytical scientists perform documented testing demonstrating that the analytical procedure meets criteria in several categories. Criteria may include factors such as repeatability, specificity and robustness. We compile a qualification plan and report, including all relevant data.

Method Validation

Under GMP conditions, method validation confirms that an analytical procedure’s performance suits its intended purpose. Depending on the method’s scope, a broad range of method characteristics, such as specificity, accuracy, precision, limit of detection/limit of quantification (LOD/LOQ), linearity and range, is considered.

During method validation, our analytical scientists perform documented testing demonstrating that the analytical procedure consistently produces a result that meets the predetermined acceptance criteria. We compile a validation plan and report that includes all relevant data.

Depending on the development phase, a fit-for-purpose validation approach can be offered, adjusting the validation required efforts in a phase-appropriate way to meet the method’s needs.

Method Verification

Compendial method verification confirms that a compendial method (e.g., from Ph. Eur. or USP) is suitable and reliable for its intended purpose under the specific conditions of the laboratory.

Unlike full method validation, compendial method verification is often considered a partial validation since the method has already undergone extensive testing and validation during its inclusion in the compendium. The extent of method verification depends on the type of method.

During method verification, our analytical scientists perform documented testing demonstrating that the developed analytical method performs adequately for the specific product or matrix being tested and within the specific laboratory where the method will be employed.

Talk to Our Experts or Request a Quote

Our expert team is ready to answer your questions and guide you to the services best suited to your program’s modality, stage and challenge. If your needs are well-defined, we’ll begin the quotation process.

Description

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