 The researchers developed modified AAV capsids that are able to target brain endothelial cells and deliver genes to them more effectively than traditional AAVs. They tested these capsids on mice, rats, marmosets, and rhesus macaques, finding that they were able to successfully deliver genes to the animal's brains. Additionally, the researchers found that the modified AAVs could be used to genetically engineer the blood-brain barrier, allowing it to become a biofactory for producing proteins. Finally, the researchers demonstrated how these modified AAVs could be used to treat a mouse model of autism, showing that they could rescue synaptic deficits caused by the absence of the gene heaven. This article was authored by Shin Hong Chen, Damien A. Wolfe, Dane Savadas and Bindu, and others.