To generate cell or animal models for gene discovery and validation and according to the mode of delivery to the target cells, there are two major modes of gene transfer:

• The ex vivo approach: primary cells are removed from the body, incubated with the vector and the genetically modified cells are either used in functional assays or are re-injected in the animal body to generate an animal model.
• The second way is only used to generate animal models and is called the in vivo approach, where the vector is directly administrated to the animal. It can be either delivered locally into the tissue or systemically into the bloodstream of the animal.

Crude batches are only generated to develop the first one application and only if the cells are very permissive for the selected viral derived vectors. In the other cases, viral batches should submited to further concentration and purification steps to increase the purity and the reproducibility. In all vector type, Vectalys keep in mind the scaleable property of the purification process we are developing.

Moreover, concentrated or not, viral stocks still contain contaminants that need to be removed to increase the potency and safety of the final product. Non purified vector preparations may contain contaminating molecules that are toxic to cells and reduce transduction efficiencies ex vivo. Some impurities contained in the vector preparation may come from reagents added in the cell culture media (serum, plasmid DNA…) and others are also released by producer cells like genomic DNA and host proteins. These preparations induce a systemic immune response and inflammation when injected in vivo.