Assessment of F/HN-pseudotyped lentiviral vector following intravenous delivery to mice

In pursuit of a gene transfer agent with efficient pulmonary transduction, the UK Respiratory Gene Therapy Consortium has developed a lentiviral vector pseudotyped with the envelope proteins, F and HN from Sendai virus (rSIV.F/HN). In contrast to other viral vectors, pulmonary rSIV.F/HN delivery achieves sustained gene expression ( ~ 2 years in mice) in the lungs and systemic circulation following a single dose. Here, we investigate the application of the rSIV.F/HN vector-platform for wider indications, including systemic disorders that require serum expression of therapeutic proteins. To assess the potential for rSIV.F/HN to produce systemic proteins, intravenous vector delivery was characterised and compared against intrapulmonary administration, achieved via 'nasal sniffing'. Both delivery routes achieved sustained (at least 1 year) systemic expression of the secreted reporter protein Gaussia luciferase. Systemic rSIV.F/HN delivery resulted in widespread protein expression across multiple organs, accompanied by the generation of significant anti-vector neutralising antibodies limiting vector readministration. Conversely, localised airway transduction was observed following pulmonary administration, which we have previously shown is not an impediment to efficient vector readministration. These data support intrapulmonary rSIV.F/HN delivery for systemic protein production, with sustained high-level transgene expression and feasible readministration.