Local and systemic administration of AAV vectors with alphaherpesvirus latency-associated promoter 2 drives potent transgene expression in mouse liver, kidney, and skeletal muscle.

Adeno-associated virus (AAV) has great potential as a source of treatments for conditions that might respond to potent and ubiquitous transgene expression. However, among its drawbacks, the genetic "payload" of AAV vectors is limited to <4.9 kb and some commonly used gene promoters are sizeable and susceptible to transcriptional silencing. We recently described a short (404 bp), potent, and persistent promoter obtained from the genome of pseudorabies virus (PrV) called alphaherpesvirus latency-associated promoter 2 (LAP2). Here, we evaluated the biodistribution and potency of transgene expression in mouse peripheral tissues in response to local and systemic administration of AAV8-LAP2 and AAV9-LAP2. We found that administration of these vectors resulted in levels of transgene expression that were similar to the larger EF1α promoter. LAP2 drives potent transgene expression in mouse liver and kidney when administered systemically and in skeletal muscle in response to intramuscular delivery. Notably, in skeletal muscle, administration of vectors with LAP2 and EF1α promoters resulted in preferential transduction of myofibers type 2. A direct side-by-side comparison between LAP2 and the EF1α promoter revealed that, despite its smaller size, LAP2 was equally potent to the EF1α promoter and resulted in widespread gene expression after IV and IM administration of AAV8 or AAV9 vectors. Collectively, these findings suggest that constructs that include LAP2 may have the capacity to deliver large therapeutically effective payloads in support of future gene therapy protocols.