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Gene Therapy Vector Capsid Evaluation Service

Capsid Analysis of Viral Vectors

Assessing the stability and integrity of viral vector capsids is essential for the development of viral vector-based gene therapies. Our company is committed to providing accurate analysis to characterize the capsid content of viral vectors, particularly adeno-associated virus (AAV) vectors. We provide precision analytics for your gene therapy for rare diseases to help you bring a safe and effective drug to market.


Viral vectors are promising tools for human gene therapy. Among these, AAV vectors have become the vectors of choice for gene therapy clinical trials. During the assembly of rAAV, the single-stranded DNA (ssDNA) genome is packaged within the capsid protein. Due to the inefficiency of the packaging, the assembled capsid is broadly divided into three types: full capsids containing the correct DNA sequence, partially-filled capsids containing truncated fragments, and empty capsids. The production of large numbers of partially filled or empty viral particles results in reduced transduction efficiency and increased immune response.

Purity analysis, empty capsid rate, and biological activity of viral vectors are key quality attributes and traditional analytical tools such as MS, SDS-PAGE, HPLC, volume exclusion chromatography (SEC), transmission electron microscopy (TEM) have been widely used to determine the percentage of full capsids in a vector preparation. However, many of these methods are low throughput and fail to resolve partially full capsids, driving the need for techniques with faster and more efficient, higher resolution capabilities.

Fig. 1 AUC distribution plots for selected prepared spike ratio samples.

Fig. 1 AUC distribution plots for selected prepared spike ratio samples. (Werle A K, et al., 2021)

Capsid Analysis Services for Viral Vectors

We combine multiple assays to help customers fully characterize the capsid content of viral vectors and provide high-resolution sample analysis information. Our services include, but are not limited to:

  • Purity analysis
    Purity analysis of AAV virus proteins is critical for the quality assurance and safety of AAV products. We offer our customers highly sensitive AAV capsid purity analysis services through capillary electrophoresis sodium dodecyl sulfate (CE-SDS) technology. This technique allows for the automatic separation of virus proteins with higher resolution, quantitative power, and better reproducibility than traditional SDS-PAGE.
  • Full/empty capsid ratio determination
    We offer techniques such as ion exchange chromatography (IEC), analytical ultracentrifugation (AUC), and capillary isoelectric focusing (cIEF) to help customers determine the ratio of full to partial or empty capsids. In addition, we provide a visual morphological assessment by TEM, combined with deep learning algorithms to enable qualitative and quantitative assessment of AAV capsids and evaluation of impurities and aggregation.
  • Genome integrity analysis
    We have established a process to detect partial and intact AAV genomes as well as small-size impurities to help customers assess the quality and correct length/size of the genome encapsulated in the capsid. Our comprehensive workflow for multiple AAV serotypes allows easy confirmation of the quality, safety, and efficacy of gene therapy.
  • Characterization of capsid proteins
    We provide customers with characterization services of AAV capsid proteins with peptide mapping to flexibly and deeply analyze the capsid identity and post-translation modifications, so as to confirm capsid quality.

Our company has established a comprehensive range of methods for screening and characterizing viral vectors for gene therapy. Our specialized and flexible capsid analysis solutions offer customers accurate analysis, providing the required information when using a small number of samples to accelerate the development of rare disease gene therapy products. If you are interested in our services, please feel free to contact us for more details.


  • Werle, A. K.; et al. Comparison of analytical techniques to quantitate the capsid content of adeno-associated viral vectors. Molecular Therapy-Methods & Clinical Development, 2021, 23: 254-262.

All of our services and products are intended for preclinical research use only and cannot be used to diagnose, treat or manage patients.

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