ASTM E2197 Viral Quantification by TCID50 Assay

The TCID₅₀ assay is a widely recognized method for quantifying infectious viral particles in biological samples. This technique has been standardized by ASTM International through the publication of ASTM E2197-23. The TCID₅₀ assay measures the number of plaque-forming units (PFUs) that can infect a 50% of cells in a cell culture. This method is particularly valuable for quality assurance and compliance with regulatory requirements, especially in sectors such as pharmaceuticals, biotechnology, and medical device manufacturing.

The TCID₅₀ assay ensures accurate quantification by using standardized protocols that minimize variability between different laboratories. This reliability is critical when dealing with potentially harmful or pathogenic viruses. The ASTM E2197 standard provides clear guidance on specimen preparation, inoculation techniques, and the interpretation of results to ensure consistent and reproducible outcomes.

The assay involves several key steps:

Preparation of cell cultures in appropriate media
Inoculation with serial dilutions of test samples
Incubation at optimal temperature for virus replication
Observation for cytopathic effects (CPE)
Dilution series analysis to determine the TCID₅₀

The result is expressed as the number of PFUs per unit volume or weight, depending on the sample. This method ensures that even small quantities of virus can be detected and quantified accurately.

This service is particularly important for ensuring product safety and efficacy by providing precise viral load data required for regulatory submissions such as Investigational New Drug (IND) applications, clinical trial protocols, and manufacturing specifications.

Applied Standards

Applied Standards for ASTM E2197 TCID50 Assay
Standard Name	Reference Number	Description
ASTM E2197-23	Test Method for Determination of Viral Quantification by TCID50 Assay	This standard outlines the procedure for quantifying infectious viral particles in biological samples using a cell culture-based assay.
ISO 4871-2019	Virus titration—Part 2: Determination of TCID50 (testicular)	This international standard provides additional guidance for the determination of infectious virus in cell culture systems, which is consistent with ASTM E2197.

Customer Impact and Satisfaction

Ensures compliance with regulatory requirements for pharmaceuticals and medical devices
Reduces the risk of product contamination or failure by providing accurate viral load data
Simplifies the submission process for clinical trials and regulatory approvals
Maintains high-quality standards in manufacturing processes

Environmental and Sustainability Contributions

Minimizes waste through efficient sample preparation techniques
Reduces energy consumption by optimizing incubation times
Promotes sustainable practices by ensuring accurate results that lead to fewer retests or revisions

Frequently Asked Questions

What is the difference between TCID₅₀ and plaque assay?

TCID₅₀ measures infectious units, while plaque assays measure non-infectious particles. The TCID₅₀ method provides a more accurate representation of the true viral load in biological samples.

How long does the assay take?

The assay typically takes 7 to 14 days, depending on the virus and sample type. This allows sufficient time for cell cultures to exhibit cytopathic effects.

Can this method be used for all types of viruses?

The TCID₅₀ assay is suitable for a wide range of viruses but may not work effectively for non-enveloped viruses that do not form plaques.

What kind of samples can be tested?

Samples can include cell cultures, tissue homogenates, and liquid samples containing viral particles. Specimen preparation is critical to ensure accurate results.

Is this method sensitive enough for low-viral-load samples?

Yes, the TCID₅₀ assay can detect very low levels of viral particles. However, sample dilutions may be necessary to ensure accurate results.

How often should this method be used?

Frequency depends on the specific application and regulatory requirements but is typically recommended for quality control checks during clinical trials or manufacturing processes.

What instruments are required?

Standard laboratory equipment such as incubators, microscopes, and pipettes are necessary. Additionally, specific cell lines must be used depending on the virus being tested.

Is this method suitable for all laboratories?

While the TCID₅₀ assay is widely accepted, specialized training and facilities are required to ensure accuracy. Not all laboratories have the necessary expertise or resources.