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Postentry Processing of Recombinant Adeno-Associated Virus Type 1 and Transduction of the Ferret Lung Are Altered by a Factor in Airway Secretions
Journal article   Open access   Peer reviewed

Postentry Processing of Recombinant Adeno-Associated Virus Type 1 and Transduction of the Ferret Lung Are Altered by a Factor in Airway Secretions

Ziying Yan, Xingshen Sun, Idil A Evans, Scott R Tyler, Yi Song, Xiaoming Liu, Hongshu Sui and John F Engelhardt
Human gene therapy, Vol.24(9), pp.786-796
09/01/2013
DOI: 10.1089/hum.2013.137
PMCID: PMC3768237
PMID: 23948055
url
https://doi.org/10.1089/hum.2013.137View
Published (Version of record) Open Access

Abstract

We recently created a cystic fibrosis ferret model that acquires neonatal lung infection. To develop lung gene therapies for this model, we evaluated recombinant adeno-associated virus (rAAV)-mediated gene transfer to the neonatal ferret lung. Unlike in vitro ferret airway epithelial (FAE) cells, in vivo infection of the ferret lung with rAAV1 required proteasome inhibitors to achieve efficient airway transduction. We hypothesized that differences in transduction between these two systems were because of an in vivo secreted factor that alter the transduction biology of rAAV1. Indeed, treatment of rAAV1 with ferret airway secretory fluid (ASF) strongly inhibited rAAV1, but not rAAV2, transduction of primary FAE and HeLa cells. Properties of the ASF inhibitory factor included a strong affinity for the AAV1 capsid, heat-stability, negative charge, and sensitivity to endoproteinase Glu-C. ASF-treated rAAV1 dramatically inhibited apical transduction of FAE ALI cultures (512-fold), while only reducing viral entry by 55-fold, suggesting that postentry processing of virus was influenced by the inhibitor factor. Proteasome inhibitors rescued transduction in the presence of ASF (∼1600-fold) without effecting virus internalization, while proteasome inhibitors only enhanced transduction 45-fold in the absence of ASF. These findings demonstrate that a factor in lung secretions can influence intracellular processing of rAAV1 in a proteasome-dependent fashion. Yan and colleagues identify a protease-sensitive factor in ferret airway secretions that profoundly reduces transduction by AAV1. The unidentified factor inhibits both vector entry and postentry processing in polarized ferret airway epithelial (FAE) cell cultures. Transduction can be rescued both in vitro and in vivo by a proteasome inhibitor, suggesting this novel factor interacts with the ubiquitin–proteasome system during intracellular virus processing.
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