Arenaviruses and lentiviral gene transfer: Host and vector properties influencing efficacy

A goal of the McCray lab is to develop lentiviral gene transfer vectors with ability to transduce human airway epithelia from the luminal surface. Successfully achieving this goal allows delivery of the cystic fibrosis transmembrane conductance regulator (CFTR) following topical or aerosol delivery of therapeutic vectors, hypothetically correcting the chloride channel defect of cystic fibrosis patients. However, human airway epithelia present several barriers to successful gene transfer and the development of vectors that can evade these is desirable.; We began our study by evaluating a lentiviral pseudotype that we believed would allow for efficient transduction of polarized airway epithelia from the apical surface. Previous publications and general consensus supported the notion that arenaviruses infect human airway epithelia following aerosol inhalation of virions. However, arenavirus pseudotyped FIV vectors failed to transduce human airway epithelia from either the apical or basolateral surfaces. Additionally, arenavirus pseudotyped FIV yielded undetectable levels of transgene expression in vivo following local and systemic delivery in adult mice. These negative results led us to investigate the reasons for inefficient transduction in airway epithelia.; Early lentiviral life cycle steps can prevent efficient transduction including receptor blocks and antiviral innate immunity. Receptor inaccessibility can be the result of improper glycosylation, poor receptor expression, or incorrect localization in polarized airway epithelia. We examined the expression and localization patterns of known arenavirus receptors (alpha-dystroglycan and transferrin receptor-I) as well as the infection polarity of wild-type arenaviruses (Chapter II). Arenavirus receptor expression was noted to be developmentally regulated prompting neonatal gene transfer experiments using arenavirus pseudotypes with high or low affinity for the receptor (Chapter III). Antiviral innate immunity was also evaluated as a possible cause for inefficient airway epithelia transduction in vitro and in vivo. Specifically, we investigated the activity of the early post-entry restriction factor, TRIM5a, against non-primate lentiviral gene transfer vectors (Chapter (V).; While failing to accomplish our original goal, we learned a great deal about arenavirus biology in human airway, identified a lentiviral pseudotype that has unique tissue and cellular tropism following neonatal delivery, and demonstrated the importance of lentiviral and animal model selection for gene transfer trials.