Human Bocavirus Type-1 Capsid Facilitates the Transduction of Ferret Airways by Adeno-Associated Virus Genomes

Abstract

Human bocavirus type-1 (HBoV1) has a high tropism for the apical membrane of human airway epithelia. The packaging of a recombinant adeno-associated virus 2 (rAAV2) genome into HBoV1 capsid produces a chimeric vector (rAAV2/HBoV1) that also efficiently transduces human airway epithelia. As such, this vector is attractive for use in gene therapies to treat lung diseases such as cystic fibrosis. However, preclinical development of rAAV2/HBoV1 vectors has been hindered by the fact that humans are the only known host for HBoV1 infection. This study reports that rAAV2/HBoV1 vector is capable of efficiently transducing the lungs of both newborn (3- to 7-day-old) and juvenile (29-day-old) ferrets, predominantly in the distal airways. Analyses of in vivo, ex vivo, and in vitro models of the ferret proximal airway demonstrate that infection of this particular region is less effective than it is in humans. Studies of vector binding and endocytosis in polarized ferret proximal airway epithelial cultures revealed that a lack of effective vector endocytosis is the main cause of inefficient transduction in vitro. While transgene expression declined proportionally with growth of the ferrets following infection at 7 days of age, reinfection of ferrets with rAAV2/HBoV1 at 29 days gave rise to approximately 5-fold higher levels of transduction than observed in naive infected 29-day-old animals. The findings presented here lay the foundation for clinical development of HBoV1 capsid-based vectors for lung gene therapy in cystic fibrosis using ferret models.

Engineered amphiphilic peptides enable delivery of proteins and CRISPR-associated nucleases to airway epithelia

“…Several viral vectors 3,6,46 , non-viral liposomes 21,47,48 , and other nanoparticle formulations are in development to address delivery challenges 49,50 , but none have advanced to widespread clinical utility. While some viral vectors overcome delivery barriers 4,5,51 , they are complex biologics and genetic payloads may exceed the capacity of some vectors. Non-viral DNA delivery approaches were also used in airway epithelia but remain inefficient, may elicit inflammatory responses following aerosol delivery 47,[52][53][54] , or lead to endosomal or lysosomal entrapment 8,11 .…”

Genetic therapies for cystic fibrosis lung disease

“…Previous clinical gene therapy studies for CF using AAV serotype 2 (AAV2) were unsuccessful due to insufficient levels of CFTR transgene expression [4*]. Recent research has focused on approaches to expand AAV tropism [6][7][8], reduce immunogenicity and enhance CFTR expression levels and persistence in the lung (Table 1). These studies exemplify the challenge of developing efficient AAV vectors for evaluation in relevant CF animal models, including pigs [4*], sheep [7], ferrets [8] and mice [6], but also provide efficient transduction of human epithelia for clinical translation.…”

“…Recent research has focused on approaches to expand AAV tropism [6][7][8], reduce immunogenicity and enhance CFTR expression levels and persistence in the lung (Table 1). These studies exemplify the challenge of developing efficient AAV vectors for evaluation in relevant CF animal models, including pigs [4*], sheep [7], ferrets [8] and mice [6], but also provide efficient transduction of human epithelia for clinical translation. For example, nine naturally occurring AAV serotypes tested in human cells and murine lungs identified AAV6 as the strongest candidate in both human and mouse epithelium [5].…”

Establishment of a Recombinant AAV2/HBoV1 Vector Production System in Insect Cells

“…Apical application of an rAAV2/HBoV1 carrying a full-length CF transmembrane conductance regulator (CFTR) cDNA of 5.4-kb to CF HAE-ALI cultures, which were made of primary airway epithelial cells of CF patients, efficiently corrected CFTR-dependent chloride transport [42]. In addition, the rAAV2/HBoV1 vector efficiently transduced ferret airways in vivo [43]. Therefore, it holds much promise for gene delivery to human airways, as well as for preclinical trials of CF gene therapy using CF ferret models [44].…”