Biological assay of recombinant adeno-associated virus gene medicine

Recombinant adeno-associated virus(rAAV) is recognized as one of the most widely used gene therapy vector in the future because it elicits minimal immune responses and mediates long-term transgene expression in a variety of cell types.Sixteen years have passed since the first clinical trial of rAAV,which have demonstrated the efficacy and safety of rAAV.However,there is still no standard method for measuring rAAV titer accurately and reliably.Presently available methods for rAAV titer assay can be divided into biological and physical assays.The biological assays seek to estimate the ability of the vector to deliver the transgene of interest and including transduction assays and infection assays.The physical assays are based on the physical properties of rAAV,such as virus particle number or packaged genomes quantity.In this review,the basic concept,principle,advantage,disadvantage and their potential applications of each type of assays for rAAV titer are discussed in detail.