Adeno-associated virus (AAV) vectors are promising clinical candidates for therapeutic gene transfer, and a number of AAV-based drugs may emerge on the market over the coming years. To insure the consistency in efficacy and safety of any drug vial that reaches the patient, regulatory agencies require extensive characterization of the final product. Identity is a key characteristic of a therapeutic product, as it ensures its proper labeling and batch-to-batch consistency. Currently, there is no facile, fast, and robust characterization assay enabling to probe the identity of AAV products at the protein level. Here, we investigated whether the thermostability of AAV particles could inform us on the composition of vector preparations. AAV-ID, an assay based on differential scanning fluorimetry (DSF), was evaluated in two AAV research laboratories for specificity, sensitivity, and reproducibility, for six different serotypes (AAV1, 2, 5, 6.2, 8, and 9), using 67 randomly selected AAV preparations. In addition to enabling discrimination of AAV serotypes based on their melting temperatures, the obtained fluorescent fingerprints also provided information on sample homogeneity, particle concentration, and buffer composition. Our data support the use of AAV-ID as a reproducible, fast, and low-cost method to ensure batch-to-batch consistency in manufacturing facilities and academic laboratories.
Keywords: AAV vectors; CMC; adeno-associated virus; capsid thermostability; gene therapy; homogeneity; identity; identity assay; manufacturing; quality control.
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