What’s the cloning capacity for recombinant AAVs?
AAV has a packaging capacity of ~4.7Kb. Since the two ITRs of AAV is about 0.2-0.3Kb in total, the foreign DNA that could be introduced between these 2 ITRs should be <4.4Kb, which is much smaller than that of recombinant adenovirus (7.5Kb). In addition, when the length of inserted DNA between the 2 ITRs is close the maximal allowed, i.e., 4-4.4Kb, the packaging efficiency decreases significantly. For instance, for gene over-expression from cDNA, since the CMV-poly(A) element is about 1Kb, so the maximal allowable cDNA length is about 3Kb. In addition, if you are interested in GFP co-expression (from a separate expression cassette), given the additional CMV-EGFP-poly(A) is about 2 Kb, so the maximal cloning capacity for GFP co-expressing system is about 1.0-1.2Kb.