When providing viral vector packaging service, we practice quality assurance measures to ensure that our customers receive high quality viral preparations. These practices include sterility measures, mycoplasma testing, and barcoding of all our plasmids and viruses.
We also take several quality control measurements. A complete explanation of our quality control practices can be found on our Viral Production page. These quality control steps are described briefly below and are performed on each lot of AAV that we distribute. Quality control data are available from Addgene upon request, for a given viral vector lot that is purchased.
Titer
AAV particles are titered by droplet digital PCR. Titers are reported as the average of at least two independent measurements. In some cases, the qPCR assay and corresponding titer determinations are also validated using AAV Reference Material (ATCC).
Next-generation Sequencing
When possible, the final viral preparation is analyzed by next-generation sequencing. Sequencing results are then analyzed for the presence of the viral genome, as well as for the absence of any contaminants.
Purity
Purity of AAV preparations is assayed by comparing the relative stoichiometric ratios of the viral capsid proteins VP1, VP2 and VP3. Samples of viral preparations are subjected to polyacrylamide gel electrophoresis (PAGE) followed by silver staining, and the molecular weight and relative intensity of the viral capsid proteins are analyzed. The abundance of viral capsid proteins as a fraction of total protein present in the sample is also determined and used to ascertain purity of the AAV preparation.
Transducibility
Whenever possible, viruses are tested in vitro for reporter gene expression to validate transduction.