With over 1,000 gene therapy clinical trials underway globally and new platform technologies emerging, developers face mounting pressure to demonstrate product quality, safety and consistency to increasingly demanding regulators.
RSSL brings over 35 years of MHRA-inspected, FDA-audited analytical expertise to this challenge designing fit-for-purpose strategies that adapt as your programme evolves from early development through to GMP batch release and commercialisation.
Vector identity and sequence verification
Process & product-related impurity profiling
Total and functional titre determination
Functional activity and potency confirmation
Regulatory safety compliance
Vector identity is confirmed through characterisation of the genetic sequence, genome integrity and capsid protein composition to ensure that the correct product is manufactured and released in accordance with regulatory requirements.
| Capsid Molecular Identity | DNA Sizing and Genomic Stability |
| Capillary Electrophoresis (CE-SDS) | CE-SDS |
| High-Resolution Liquid Chromatography Mass Spectrometry (HR-LC-MS) | qPCR/PCR |
| SDS-PAGE | Restriction Enzyme mapping |
| Immunoassay-based methods (ELISA, Western Blot) |
We accurately assess the purity of your viral vector products by detecting and quantifying contaminants and process and product-related impurities including host cell proteins, residual DNA and empty capsids, supporting regulatory compliance and consistent product quality.
Molecular variants of viral vector that contribute to the overall purity assessment and may ultimately impact potency and safety. According to ICH Q6B guidelines, these impurities must be characterised and controlled throughout the manufacturing process and for batch release.
Examples include empty:full capsid ratio, defective or immature viral particles, aggregates and others.
| Empty:full capsid characterisation | Aggregates |
| Liquid Chromatography (SEC or IEX) | Size Exclusion Chromatography (SEC) |
| Capillary Electrophoresis | Dynamic Light Scattering (DLS) |
Accurate measurement of viral particle titer and infectivity is critical to ensuring reliable dosing, product consistency, and therapeutic efficacy. Validated analytical methods are used to quantify total and functional viral titers, supporting robust product characterization and batch-to-batch reproducibility.
Calculated through integrated analysis of physical, genomic, & infectious titer measurement
We evaluate functional activity and expression of your transgene to confirm therapeutic efficacy. RSSL can also perform assays for infection dynamics (kinetics) studies via cell-based assays with multiple endpoints such as qPCR and ELISA.
| Transgene/Protein Expression Analysis | Potency and Functionality |
| Protein Expression: Immunoassays such as ELISA and Western Blotting | A range of cell-based assays, including reporter cell lines |
| mRNA Expression: RT-qPCR | Infection dynamics (kinetics) studies via cell-based assays with multiple endpoints (e.g., qPCR, ELISA) |
We provide rapid, sensitive, and compliant biosafety testing services to ensure the safety and quality of your biotherapeutic products including, mycoplasma, endotoxin and sterility testing. Our assays help mitigate contamination risks and support regulatory approval at every stage of development and manufacturing.
Put 35 years of MHRA-inspected, FDA-audited analytical expertise at your disposal. With full UKAS accreditation our fully compliant analysis will support projects large and small.
Get in touch to discuss how RSSL can support your project.
Batch release typically includes identity, purity, potency, sterility, endotoxin, mycoplasma, viral titre and particle characterisation. All performed in RSSL's MHRA-inspected laboratories and aligned with ICH Q6B.
Outsourcing to an MHRA-inspected, UKAS-accredited partner like RSSL provides immediate access to validated methods, regulatory experience, and qualified scientists — without the cost of building in-house GMP capability.
Impurities such as host cell proteins, residual DNA, and empty capsids can impact patient safety, efficacy, and immunogenicity. Comprehensive profiling using orthogonal techniques ensures regulatory compliance and consistent product quality.
Methods are developed and validated using orthogonal techniques (chromatography, electrophoresis, mass spectrometry, immunoassays) to provide comprehensive impurity profiles satisfying MHRA, FDA, and EMA expectations.
Start-ups gain immediate access to GMP infrastructure, regulatory expertise, and validated methods — enabling faster IND/CTA submissions without capital expenditure, reducing time-to-clinic by months.
Total DNA is quantified using PicoGreen® fluorescence assays, while host-specific hcDNA is detected via qPCR for relevant production hosts (E. coli, CHO, HEK293) aligned with USP <509>.
We use cell-based potency assays (including reporter cell lines), infection kinetics studies, and immunoassays (ELISA, western blot) to confirm transgene expression and functional biological activity.
