As of January 2020 Addgene switched from qPCR to ddPCR for AAV titering. ddPCR is more accurate than qPCR and, because it does not rely on a standard curve, improves consistency of reported titers across lots. Due to the accuracy and sensitivity of the assay, however, ddPCR titers tend to be ~2-fold higher than those measured by qPCR. For the purpose of your experiments, please be advised that the potency of the virus has not changed. Consequently, if comparing a new ddPCR titered lot to an old qPCR titered lot of the same virus you should not dilute your virus 2-fold. For example, if you previously used 1x1011 GC of a qPCR’d lot of virus when reproducing the experiment you will need to use at least 2x1011 GC of a ddPCR’d lot. This change is effective for all AAV lot numbers above v69007. As always, blue capped vials have been produced by Upenn and were titered by ddPCR.