The morphological characterization of gene therapy delivery platforms can support the drug development process by identifying typical product-related impurities and analyzing of the capsids packaging. Gene delivery empty viral capsids may be the result of failure in packaging or occur because of structural changes of the capsid during the manufacturing process – the latter being not only a risk for lowered potency but also representing a safety issue for the patient, as particles with a damaged capsid may provoke immunogenicity issues. Transmission electron microscopy (TEM) can provide unique insights in the characterization of viral gene delivery platforms such as adeno-associated viruses (AAVs), adenoviruses and retroviruses. TEM images, taken either by traditional electron microscopes, or by more modern, compact low voltage electron microscopes, can be analyzed with automated software specifically designed for the characterization of viral particles. Such software can be used to automatically analyze specimens and give indications on the integrity of the particles and on the presence and nature of process related impurities. TEM analysis of negatively stained samples (nsTEM) can provide insights on the morphology of the viral vectors present in a specimen, where a qualitative assessment can be made on the intactness of the particles, and on the presence and characterization of impurities. TEM analysis of Cryo-preserved samples (cryoTEM) can assess the encapsulation of vectors such as AAV and can be employed as a GMP validatable method suitable for QC testing of the ratio of full AAV particles. In this presentation results obtained from automated analyses using both these techniques will be presented.

Automated characterization of gene therapy viral vectors: Packaging, purity and integrity using transmission electron microscopy

2019 Spring National Meeting

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