ADENOVIRUS-MEDIATED PERSISTENT CYSTIC-FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR EXPRESSION IN MOUSE AIRWAY EPITHELIUM

Replication-defective adenovirus (Ad) vectors have been used for gene transfer to the respiratory epithelium of experimental animals and ind ividuals with cystic fibrosis, Studies from several laboratories have suggested that administration of first-generation Ad vectors results o nly in transient gene expression in the lung, due at least in part to destruction of vector-transduced cells by host cellular immune respons es directed against viral proteins and/or immunogenic transgene produc ts,We have constructed new Ad2-based, El deleted vectors encoding a we akly immunogenic transgene, the human cystic fibrosis transmembrane co nductance regulator (hCFTR) under the control of the cytomegalovirus e nhancer-promoter. These vectors contain wild-type E2 and E4 regions. T hese new Ad/CFTR vectors were instilled into the lungs of immunocompet ent C57BL/6, BALB/c, and C3H mice. In vitro cytotoxic T lymphocyte (CT L) analysis indicated the presence of Ad-specific CTLs in treated mice . However, we were not able to demonstrate a CTL response specific for hCFTR Reverse transcriptase PCR analysis demonstrated that hCFTR mRNA expression continued in all three strains of mice for at least 70 day s, the last time point analyzed. The E3 region did not play a signific ant role in persistence of the Ad/CFTR vectors in the mouse lung. Func tional hCFTR expression was also observed in the nasal epithelia of CF mutant mice. These results suggest that long-term expression of hCFTR is possible in the airway epithelia of immunocompetent mice without r adical modification of Ad vector and in spite of the presence of CTLs.