Virus Particle Quantification by QnsTEM
GMP-validated quantitative transmission electron microscopy for accurate viral particle enumeration and analytical standardization.
Virus Particle Quantification using Quantitative Negative Staining Transmission Electron Microscopy (QnsTEM) is a GMP-validated analytical method for the direct measurement of viral particles and virus-like particles (VLPs) based on morphology and calibrated electron microscopy imaging.
QnsTEM enables absolute particle quantification in biological systems, providing a direct alternative to indirect molecular or infectivity-based assays.
Why Quantify Viral Particles?
Accurate viral particle quantification is essential for:
• Bioprocess development and optimization
• Vaccine and viral vector characterization
• Batch-to-batch comparability
• Regulatory submissions and documentation
• Orthogonal validation of molecular and infectivity assays
Traditional analytical methods often measure infectivity or nucleic acid content rather than total particle number, which can lead to incomplete or non-comparable results.
QnsTEM addresses this gap by enabling direct visualization and enumeration of all detectable viral particles, independent of infectivity or genome content.
QnsTEM Quantification Principle
QnsTEM is based on a calibration-driven electron microscopy approach.
Instead of relying on indirect inference or spike-in reference beads, QnsTEM uses:
• Defined calibration grids with known particle density
• Standardized imaging and counting workflows
• Statistical correlation between observed particle counts and concentration
This approach enables robust conversion from microscopic observations to absolute particle concentration values.
Key Advantages of QnsTEM Quantification
- Direct visualization of viral particles
- Absolute (not relative) particle quantification
- Key Advantages of QnsTEM Quantification
- Direct visualization of viral particles
- Absolute (not relative) particle quantification
- Bead-free calibration system
- Reduced operator-dependent variability
- High reproducibility across studies
- Suitable for diverse viral and VLP systems
- GMP-compliant and validation-backed methodology
Quality Assurance and Validation
All QnsTEM analyses are performed under GMP-compliant conditions using validated procedures, qualified instrumentation, and trained personnel.
To ensure data integrity, predefined System Suitability Criteria (SSC) are evaluated prior to analysis. Only samples meeting all acceptance criteria are processed.
Validation studies were conducted using well-characterized virus reference materials spanning a broad range of particle sizes and morphologies, including small non-enveloped viruses such as adeno-associated virus (AAV) and large enveloped virus-like systems, such as poxvirus-derived reference materials. Particle concentrations were established using independent quantitative reference methods.
Turnaround Time
Final reports (Certificate of Analysis) can be issued within 5 working days.