Tail vein delivery of single-chain and 2-chain AAV vectors. The efficacy of AAV8 as a single vector and 2 vectors delivered via tail vein was evaluated at 1 × 10¹¹ gc/mouse. However, AAV2 was tested only as a single-chain vector by this route. Tail vein administration of AAV8 was as efficacious as intraportal delivery irrespective of the single- or 2-vector approach. In contrast, this route was not efficacious for the AAV2 single-chain vector. Error bars represent the mean ± SD.