The Alphaherpesvirus Latency Associated Promoter 2 (LAP2) Drives Strong Transgene Expression in Peripheral Tissue Depending on Administration Route and AAV Serotype

Abstract Adeno-associated virus (AAV) has shown great translational potential in treating a variety of diseases often requiring strong and ubiquitous transgene expression. However, the genetic payload of AAV vectors is limited to <4.9 kb and some commonly used gene promoters are large in sizeable and susceptible to transcriptional silencing. We validated a short (404 bp), strong and persistent promoter obtained from the genome of pseudorabies virus (PRV) called alphaherpesvirus latency-associated promoter 2 (LAP2). We evaluated the biodistribution and potency of transgene expression in mouse peripheral tissue and organs when using AAV8-LAP2 and AAV9-LAP2, both of which achieved transgene expression like that of the ubiquitous promoter, EF1α. LAP2 drives potent transgene expression in liver and kidney after systemic retro-orbital administration and in skeletal muscle after intramuscular delivery. Additionally, we observed broad transduction throughout the lung albeit at lower levels than other tissues. Notably, in skeletal muscle LAP2 resulted in preferential transduction of myofiber types 2. A direct side-by-side comparison between LAP2 and EF1α, demonstrates that regardless of the AAV serotype and route of administration, LAP2 is as powerful and persistent as EF1α promoter despite being 66% smaller in size, thus allowing for larger therapeutic payloads.