Adeno-associated virus (AAV) is a promising vector for in vivo gene therapy because of
its excellent safety profile and ability to mediate stable gene expression in human subjects. However,
there are still numerous challenges that need to be resolved before this gene delivery vehicle is
used in clinical applications, such as the inability of AAV to effectively target specific tissues, preexisting
neutralizing antibodies in human populations, and a limited AAV packaging capacity.
Over the past two decades, much genetic modification work has been performed with the AAV capsid
gene, resulting in a large number of variants with modified characteristics, rendering AAV a
versatile vector for more efficient gene therapy applications for different genetic diseases.