Optimization of adeno-associated viral (AAV) gene therapies vectors for balancing efficacy, longevity and safety for clinical application.

Adeno-associated viral (AAV) vectors are an ideal platform for gene therapy due to their ability to deliver therapeutic cargos safely and effectively across various target organs. Their low immunogenicity contributes to long-lasting therapeutic effects. However, recent insights highlight the significance of CpG content within AAV vectors, where unmethylated CpG dinucleotides can trigger a TLR9-mediated immune response, leading to the rapid elimination of transduced cells. Clinical evidence indicates an inverse relationship between CpG content and therapeutic success, with lower CpG counts correlating with sustained transgene expression. Here, we sought to optimize a novel, CpG-rich AAV8 vector, referred to as pVR59, designed for treating lipoprotein lipase deficiency (LPLD). We strategically reduced CpG levels in pVR59, resulting in the development of pNC182, a CpG-depleted vector that maintains therapeutic efficacy. A single intramuscular injection of pNC182 demonstrated comparable effectiveness to pVR59 in normalizing lipemia and hypertriglyceridemia in LPLD mouse models, with a 38% reduction in total CpG count. These findings support the clinical application of pNC182 as a safe, long-lasting AAV gene therapy for LPLD and provide a framework for future AAV vector designs aimed at maximizing therapeutic efficacy while minimizing immunogenic responses in human settings.