Modification of an adenoviral vector with biologically selected peptides: a novel strategy for gene delivery to cells of choice.

Recombinant adenoviruses are currently being used as vectors for gene delivery to a wide variety of cells and tissues. Although generally efficacious for gene transfer in vitro, improvement in the efficiency of vector delivery in vivo may aid several gene therapy applications. One major obstacle is the lack of high-affinity viral receptors on the surface of certain cells that are targets for gene therapy. In principle, incorporation of avid, cell-specific ligands into the virion could markedly improve vector entry into the desired tissues. We have developed a strategy for addressing this issue in the lung by biopanning differentiated, ciliated airway epithelial cells against a phage display library. The peptide with the most effective binding was coupled to the surface of an adenovirus using bifunctional polyethylene glycol (PEG) molecules. The chemically modified adenoviral vector was able to effect gene transfer to well-differentiated human airway epithelial cells by an alternative pathway dependent on the incorporated peptide. Coupling of PEG to the surface of the virus also served to partially protect the virus from neutralizing antibodies in vitro. These experiments will aid in the design of improved adenoviral vectors with the capacity for more specific and efficient delivery of therapeutic genes to desired target tissues. We have used a novel method for enhancing gene delivery to target cells by coupling a biologically selected peptide to the surface of an adenovirus with bifunctional PEG molecules. Modification of the viral capsid by the addition of a peptide with binding preference for differentiated ciliated airway epithelia allowed gene delivery to those cells by a novel entry pathway. Incorporation of the CFTR gene in a similarly modified vector resulted in correction of defective Cl- transport in well-differentiated epithelial cultures established from human cystic fibrosis (CF) donors. The presence of PEG molecules on the surface of the virus served, in addition, to reduce antibody neutralization. Modification of adenoviruses with PEG/peptide complexes can serve to partially overcome the barrier of inefficient gene transfer in some cell types and some of the adverse immunological responses associated with gene delivery by these vectors.

Pendred syndrome, DFNB4, and PDS/SLC26A4 identification of eight novel mutations and possible genotype-phenotype correlations.

Mutations in PDS (SLC26A4) cause both Pendred syndrome and DFNB4, two autosomal recessive disorders that share hearing loss as a common feature. The hearing loss is associated with temporal bone abnormalities, ranging from isolated enlargement of the vestibular aqueduct (dilated vestibular aqueduct, DVA) to Mondini dysplasia, a complex malformation in which the normal cochlear spiral of 2(1/2) turns is replaced by a hypoplastic coil of 1(1/2) turns. In Pendred syndrome, thyromegaly also develops, although affected persons usually remain euthyroid. We identified PDS mutations in the proband of 14 of 47 simplex families (30%) and nine of 11 multiplex families (82%) (P=0.0023). In all cases, mutations segregated with the disease state in multiplex families. Included in the 15 different PDS allele variants we found were eight novel mutations. The two most common mutations, T416P and IVS8+1G>A, were present in 22% and 30% of families, respectively. The finding of PDS mutations in five of six multiplex families with DVA (83%) and four of five multiplex families with Mondini dysplasia (80%) implies that mutations in this gene are the major genetic cause of these temporal anomalies. Comparative analysis of phenotypic and genotypic data supports the hypothesis that the type of temporal bone anomaly may depend on the specific PDS allele variant present.