Bovine AAV - a promising vector for pulmonary gene therapy

Efficient systemic delivery to the lung remains a major barrier for adeno-associated virus (AAV)-mediated pulmonary gene therapy, particularly when pre-existing immunity limits the use of conventional capsids. Here, we evaluated Bovine AAV, a phylogenetically divergent capsid, as candidate vector for lung-directed gene transfer. In adult C57BL/6J mice, intravenous delivery of Bovine AAV resulted in robust and preferential lung transduction comparable to AAV4, with predominant targeting of alveolar type I pneumocytes and pulmonary endothelial cells. In primary human lung-resident cells, Bovine AAV was particularly effective in microvascular endothelial cells, a target poorly transduced by AAV4 in vitro. Bovine AAV demonstrated scalable production with yield, purification performance, capsid quality, and genome integrity comparable to AAV9. In sera from healthy adults from the United States and Switzerland, Bovine AAV showed intermediate neutralization frequencies, lower than AAV2 and AAV4 but higher than AAV5 and AAV9. Of relevance, Bovine AAV maintained in vivo transduction efficiency in mice previously immunized with a pool of human and non-human primate-derived AAV capsids, including AAV4. Together, these results position Bovine AAV as a promising lung-tropic and immune-distinct vector for pulmonary gene therapy, with particular relevance for applications requiring systemic delivery in the presence of pre-existing immunity to conventional serotypes.