Adeno-associated virus as a gene therapy vector: strategies to neutralize the neutralizing antibodies

Towards the optical cochlear implant: optogenetic approaches for hearing restoration

“…AAVs appear to be highly promising candidates, since they have little potential for virus-related harm in the transduced tissue, while being characterized by an intrinsically high neural tropism, long-term availability of the desired transgene, and high expression levels (Willett & Bennett, 2013;Ahmed et al, 2017;Hudry & Vandenberghe, 2019;Lotfinia et al, 2019). Experimentally, AAVs have been used in several studies to genetically restore auditory function, and even reached clinical trials for the treatment of various other disorders, including retinal dysfunction (Akil et al, 2012;Askew et al, 2015;Landegger et al, 2017;Pan et al, 2017;Suzuki et al, 2017;Al-Moyed, 2019;Hudry & Vandenberghe, 2019;Lotfinia et al, 2019). In fact, a first AAV-mediated gene therapy for vision restoration (Luxturna) has recently been FDA-approved (Keeler & Flotte, 2019;Lotfinia et al, 2019).…”

“…Experimentally, AAVs have been used in several studies to genetically restore auditory function, and even reached clinical trials for the treatment of various other disorders, including retinal dysfunction (Akil et al, 2012;Askew et al, 2015;Landegger et al, 2017;Pan et al, 2017;Suzuki et al, 2017;Al-Moyed, 2019;Hudry & Vandenberghe, 2019;Lotfinia et al, 2019). In fact, a first AAV-mediated gene therapy for vision restoration (Luxturna) has recently been FDA-approved (Keeler & Flotte, 2019;Lotfinia et al, 2019). Furthermore, AAV optimization by in silico reconstruction and targeted evolution resulted in powerful AAV variants such as Anc80, AAV2/7m8, PHP.B, and PHP.eB, which are characterized by increased efficiency of viral transduction in various tissues, including cochlear hair cells and SGNs (Dalkara et al, 2013;Zinn et al, 2015;Deverman et al, 2016;Chan et al, 2017;Landegger et al, 2017;Keppeler et al, 2018).…”

“…Neutralizing antibodies to AAVs can also arise after the first virus administration, then challenging a second injection, e.g., in the other ear for rehabilitation by bilateral oCI (Mendoza et al, 2017;Hudry & Vandenberghe, 2019). Strategies to overcome this limitation include the use of empty capsids that bind neutralizing antibodies, the use of different serotypes, engineered capsids with reduced sensitivity to neutralizing antibodies, and shielding of the viral capsids (Mingozzi & High, 2013;Lotfinia et al, 2019).…”

Protocol for In Vivo Evaluation and Use of Destabilizing Domains in the Eye, Liver, and Beyond

“…AAV has the smallest carrying capacity of the three viruses listed herein, harboring only ~4.7 kb, but produces almost no human immune response within the host and can target specific cells through serotype altering ( Benskey et al, 2019 ). However, AAV neutralizing antibodies to at least one of the almost 100 naturally occurring serotypes do exist in an estimated 70% of humans and non-human primates, which has proven to be a major limitation in human clinical trials ( Lotfinia et al, 2019 ). AAV remains episomal and circularized in the nucleus following infection, providing persistent, long-term expression in nondividing cells ( Choudhury et al, 2017 ).…”

Efficient viral delivery of Cas9 into human safe harbor

“…For precise gene editing using homology-directed repair (HDR), the Cas9 gene, single-guide RNA (sgRNA), and homology arms must be introduced. Cas9 delivery is usually performed using transfection or electroporation, in vitro, as it is too large to pack into an adeno-associated virus (AAV) vector bundled with homology arms 8,9 . To solve this problem, SaCas9 from Staphylococcus aureus, which is smaller than SpCas9, was used to package the AAV vector 10 .…”