AAV-8 and AAV-9 Vectors Cooperate with Serum Proteins Differently Than AAV-1 and AAV-6

Abstract

Under intravenous delivery, recombinant adeno-associated vectors (rAAVs) interact with blood-borne components in ways that can critically alter their therapeutic efficiencies. We have previously shown that interaction with human galectin 3 binding protein dramatically reduces rAAV-6 efficacy, whereas binding of mouse C-reactive protein improves rAAV-1 and rAAV-6 transduction effectiveness. Herein we have assessed, through qualitative and quantitative studies, the proteins from mouse and human sera that bind with rAAV-8 and rAAV-9, two vectors that are being considered for clinical trials for patients with neuromuscular disorders. We show that, in contrast to rAAV-1 and rAAV-6, there was a substantial similarity in protein binding patterns between mouse and human sera for these vector serotypes. To establish an in vivo role for the vector binding of these sera proteins, we chose to study platelet factor 4 (PF4), which interacts with both vectors in both mouse and human sera. Experiments using PF4-knockout mice showed that a complete lack of PF4 did not alter skeletal muscle transduction for these vectors, whereas heart transduction was moderately improved. Our results strongly support our position that the impact of serum proteins on the transduction properties of rAAV-8 and rAAV-9, already observed in mouse models, should be similar in human preclinical trials.

Adeno-associated virus vector as a platform for gene therapy delivery

“…It is now increasingly appreciated that host factors impacting the potency of gene delivery come into play as soon as the rAAV is administered to the patient. For example, new findings indicate that different serotypes interact with serum proteins in different ways 36 . Nonetheless, the effectiveness of rAAV is in large part determined by the molecular interactions between the capsid and target cell surface receptors 37,38 and subsequent downstream events following particle internalization 39 (FIG.…”

An engineered serum albumin-binding AAV9 capsid achieves improved liver transduction after intravenous delivery in mice

“…Although we do not observe a noticeable improvement in skeletal muscle transduction, we do see significantly increased liver transduction by AAV9-ABDCon after systemic administration in vivo, a finding which has also been reported in studies evaluating the impact of AAV8 pre-incubation in HSA (10,11). However, in contrast to these prior studies, Denard and colleagues were unable to detect AAV8 binding to HSA, suggesting that a mechanism other than serum albumin-binding may be responsible (21). Altogether, our results suggest serum albumin-binding may be an effective approach to improve the efficiency of AAV vector-mediated gene delivery to the liver, which may be beneficial in the clinical development of improved AAV vectors for liver-directed gene delivery.…”

Transduction Efficiency of Adeno-Associated Virus Serotypes After Local Injection in Mouse and Human Skeletal Muscle

“…Whereas the comparison of serotypes has been largely described via systemic delivery, to our knowledge very few studies have compared their efficiency after a local intramuscular injection. In addition, while it is known that the potency of rAAV gene delivery can be impacted by several host factors, such as the molecular interactions between the capsid and target cell surface receptors 30 or the interaction with serum proteins in the circulation 31 , the impact of fibrosis by extracellular matrix deposition around muscle fibers on rAAV transduction efficiency and the transduction of interstitial fibrosis cells has not been evaluated.…”