# A Rationally Designed AAV9-DM Capsid with Minimal Liver Tropism

## TL;DR

Researchers designed a new AAV9 variant, AAV9-DM, that reduces liver targeting while maintaining the ability to transduce other tissues, including the central nervous system.

## Contribution

A rationally designed AAV9 capsid variant with minimal liver tropism and similar biodistribution to AAV9.

## Key findings

- AAV9-DM shows ~127-fold lower liver transduction compared to AAV9 in mice.
- AAV9-DM maintains similar biodistribution to AAV9 and provides durable transgene expression in mice.
- AAV9-DM enables targeting of extrahepatic tissues, especially the CNS, with reduced liver toxicity.

## Abstract

What are the main findings?
The AAV9-DM capsid results in ~127 fold lower liver transduction as compared to AAV9 in mice.The AAV9-DM capsid exhibits a biodistribution similar to AAV9 and results in durable transgene expression in mice.

The AAV9-DM capsid results in ~127 fold lower liver transduction as compared to AAV9 in mice.

The AAV9-DM capsid exhibits a biodistribution similar to AAV9 and results in durable transgene expression in mice.

What are the implications of the main findings?
AAV9-DM can be used to target extrahepatic tissue, especially the CNS, while avoiding liver transduction.AAV9-DM may allow for the use of lower doses when targeting the CNS via peripheral injection, resulting in reduced immune responses in the clinic.

AAV9-DM can be used to target extrahepatic tissue, especially the CNS, while avoiding liver transduction.

AAV9-DM may allow for the use of lower doses when targeting the CNS via peripheral injection, resulting in reduced immune responses in the clinic.

Adeno-associated viral vectors (AAV) are the leading gene therapy in the clinic. AAV9 has been of particular interest due to its wide tropism for multiple tissue types as well as being able to cross the blood-brain barrier and transduce central nervous system tissues. However, effectively and safely targeting extrahepatic tissue following the systemic administration of AAV9 remains a challenge due to high rates of liver transduction and liver toxicity. Thus, a crucial first step in developing a safe AAV9-based vector is to reduce liver targeting. Here we utilized rational design techniques to make five point mutations in the AAV9 capsid. In doing so, we developed a novel AAV9 variant, AAV9-DM, that is characterized by reduced liver tropism as compared to AAV9 and other liver de-targeted AAV9 mutants. We show that AAV9-DM is effective at transducing cells in vivo, resulting in robust transgene expression over a 9-week period. Importantly, the AAV9-DM capsid maintains the ability to transduce non-hepatic tissues with a biodistribution similar to AAV9. This new mutant represents a novel AAV capsid that may be the basis for developing safer therapeutics to target extrahepatic tissue while reducing adverse side effects related to liver transduction.