Single amino acid insertion allows functional transduction of murine hepatocytes with human liver tropic AAV capsids.

Recent successes in clinical gene therapy applications have intensified the interest in using adeno-associated viruses (AAVs) as vectors for gene delivery into human liver. An inherent intriguing characteristic of AAVs is that vector variants vary substantially in their ability to transduce hepatocytes from different species. This has historically limited the value of preclinical studies using rodent models for predicting the efficiency of AAV vectors in liver-targeted gene therapy clinical studies. In this work, we aimed to investigate the key determinants of the observed differential interspecies transduction abilities among AAV variants. We took advantage of domain swapping strategies between AAV-KP1, a newly identified variant with enhanced murine liver tropism, and AAV3b, which functions poorly in mice. The systematic in vivo comparison of AAV3b/AAV-KP1 chimeric variants allowed us to identify a threonine insertion at position 265 within variable region I (VR-I) as the key residue that confers murine hepatic transduction to human-derived clade B (AAV2-like) and clade C (AAV3b-like) variants. We propose to use this insertion to generate phylogenetically related AAV surrogates in support of toxicology and dosing studies in the murine liver model.
Competing Interests: M.C.-C., I.E.A., and L.L. are inventors on patent applications filed by Children’s Medical Research Institute related to AAV capsid sequences and in vivo function of novel AAV variants. L.L. is a co-founder and scientific advisor of LogicBio Therapeutics. L.L. and I.E.A. are co-founders of Exigen Biotherapeutics. L.L. has a sponsored research agreement with LogicBio Therapeutics. M.C.-C., I.E.A. and L.L. have intellectual property (IP) licensed to biopharmaceutical companies. L.L. and I.A.E. have consulted on technologies addressed in this paper. L.L. and I.A.E. have stock and/or equity in companies with technology broadly related to this paper. The remaining authors declare no competing interest.
(© 2021 The Author(s).)