An AAV2/5 Vector Enhances Safety of Gene Transfer to the Mouse Salivary Gland

Abstract

This study was designed to improve AAV-mediated gene transfer to the murine submandibular salivary glands. Our first aim was to utilize AAV pseudotype vectors, containing the genetic elements of the canonical AAV2, packaged within capsids of AAV serotypes 5, 8, and 9. Having determined that this pseudotyping increased the efficiency of gene transfer to the glands by several orders of magnitude, we next asked whether we could reduce the gene transfer inoculum of the pseudotype while still achieving gene transfer comparable with that achieved with high-dose AAV2. Having achieved gene transfer comparable with that of AAV2 using a pseudotype vector (AAV2/5) at a 100-fold lower dose, our final objective was to evaluate the implications of this lower dose on two pre-clinical parameters of vector safety. To evaluate systemic toxicity, we measured AAV vector sequestration in the liver using qPCR, and found that the 100-fold lower dose reduced the vector recovered from the liver by 300-fold. To evaluate salivary gland function, we undertook whole-proteome profiling of salivary gland lysates two weeks after vector administration and found that high-dose (5 × 10⁹) AAV altered the expression level of ~32% of the entire salivary gland proteome, and that the lower dose (5 × 10⁷) reduced this effect to ~7%.