General Introduction of AAV, rAAV and rAAV Vector

Adeno-associated virus (AAV) is inherently replication-deficient virus that belongs to the family Parvoviridae. It is single-stranded DNA virus with very simple structure. Adeno-associated viral which has been artificially recombined called recombinant adeno-associated viral (rAAV). And recombinant adeno-associated viral used in scientific research is unusually called rAAV vector.

The rAAV vectors consist of a simple capsid with a single-stranded DNA genome and no viral coding sequences. Its limited ability to transduce dendritic cells results in its limited immune responses.They are nonimmunogenic and can transduce both dividing and nondividing cells. Different rAAV serotypes may transduce diverse cell types. All those features make rAAV vectors excellent tools to study the function of neuropeptides in local brain areas. And they can also be used to locally or systemically enhance or silence gene expression.

In recent years rAAV vectors have become increasingly valuable for in vivo studies in animals and are also currently being tested in human clinical trials. rAAV vector has proven to be very useful vector for efficient and long-term gene transfer in a variety of tissues including lung, muscle, brain, spinal cord, retina and liver, thus the use of rAAV vectors holds great promise for human gene therapy. Its advantages observed in numerous disease paradigms, such as, the broad host range, low level of immune response, and longevity of gene expression has enabled the initiation of a number of clinical trials.

In the past, rAAV was most often generated through the co-transfection of rAAV vector plasmid and wild-type AAV helper plasmid into Ad-infected cells. Now Ad-infected cells is no longer necessary due to the improvements in AAV helper design as well as construction of non-infectious mini-Ad plasmid helper, which has improved the yield of rAAV per transfected cell in a crude lysate. Scalable methods of rAAV production have been developed too, which means that rAAV production will no longer rely on DNA transfection. More scale-up production of rAAV has become possible in some laboratories.