Novel Adeno-associated Viruses Derived From Pig Tissues Transduce Most Major Organs in Mice

Abstract

Recently, development of Adeno-associated virus (AAV) vectors has been focusing on expanding the genetic diversity of vectors from existing sequences via directed evolution or epitope remapping. Apart from intelligent design, AAV isolation from natural sources remains an important source of new AAVs with unique biological features. In this study, several new AAV sequences were isolated from porcine tissues (AAVpo2.1, -po4, -po5, and -po6), which aligned in divergent new clades. Viral particles generated from these sequences displayed tissue tropism and transduction efficiency profile specific to each porcine-derived AAV. When delivered systemically, AAVpo2.1 targeted the heart, kidney, and muscle, AAVpo5 performed poorly but was able to transduce muscle fibers when injected intramuscularly, whereas AAVpo4 and -po6 efficiently transduced all the major organs sampled, contending with ‘gold-standard’ AAVs. When delivered systemically, AAVpo4 and -po6 were detected by polymerase chain reaction (PCR) and histochemical staining of the transgene product in adult mouse brain, suggesting that these vectors can pass through the blood-brain barrier with efficiencies that may be useful for the development of therapeutic approaches. Porcine tissues are antigenically similar to human tissues and by inference, porcine AAVs may provide fresh tools to contribute to the development of gene therapy-based solutions to human diseases.

Bat adeno-associated viruses as gene therapy vectors with the potential to evade human neutralizing antibodies

“…However, from another perspective, the bats could also be a potential source for virus isolation and vector development. Novel AAV vectors have also been isolated from other nonprimate mammals including cattle, goats, and pigs [11][12][13]. A common attribute of these AAV vectors was their efficient evasion of preexisting immunity from human AAV antibodies.…”

“…The discovery of novel AAV serotypes and directed evolution remain two important genetic approaches to enhance AAV in its capacity to evade preexisting human neutralizing antibodies. For instance, numerous AAV serotypes have been successively isolated from cattle, goats, and pigs [11][12][13]. The bovine and caprine AAVs showed potential to evade neutralization of human antibodies, while the porcine AAV demonstrated distinct tissue tropism from primate AAVs.…”

Viral vector-mediated gene therapies

“…In order to improve tissue specificity, efficiency and avoidance of neutralizing antibodies in serum, a variety of new types of AAV are being discovered (12) and existing AAV capsids are being modified using rational and random design (13, 14). Thus, the optimal AAV serotype for human gene therapy of muscle disorders may not yet be known.…”

Systemic Vascular Transduction by Capsid Mutant Adeno-Associated Virus After Intravenous Injection

“…As a consequence, the ability to permanently modify endothelial cells through gene augmentation represents an exciting therapeutic avenue for the treatment of chronic vascular disease, potentially allowing long-term treatment to be achieved after a single intervention. However, previous efforts to target vascular endothelial cells in vivo through intravenous administration of native DNA 17 or of recombinant adeno-associated viral (rAAV) 18,19 or adenoviral vectors 20,21 have proven to be ineffectual, resulting in minimal vascular transduction and, frequently, acute systemic toxicity. 22,23 Attempts have been made to improve on the native properties of rAAV vectors by introducing targeted mutations within the shared C-terminal domain of the structural proteins (VP1/VP2/VP3) that comprise the viral capsid (see Fig.…”