Rémi Villenave, Lindsay Broadbent, Isobel Douglas, Jeremy D. Lyons, Peter V. Coyle, Michael N. Teng, Ralph A. Tripp, Liam G. Heaney, Michael D. Shields, Ultan F. Power

Airway epithelium is the primary target of many respiratory viruses. However, virus induction and antagonism of host responses by human airway epithelium remains poorly understood. To address this, we developed a model of respiratory syncytial virus (RSV) infection based on well- differentiated pediatric primary bronchial epithelial cell cultures (WD-PBECs) that mimics hallmarks of RSV disease in infants. RSV is the most important respiratory viral pathogen in young infants worldwide. We found that RSV induces a potent antiviral state in WD-PBECs that was mediated in part by secreted factors, including interferon lambda-1 (IFNλ1)/IL-29. In contrast, type I interferons were not detected following RSV infection of WD-PBECs., Interferon (IFN) responses in RSV-infected WD-PBECs reflected those in lower airway samples from RSV-hospitalized infants. In view of the prominence of IL-29, we determined whether recombinant IL-29 treatment of WD-PBECs before or after infection abrogated RSV replication. Interestingly, IL-29 demonstrated prophylactic, but not therapeutic, potential against RSV. The absence of therapeutic potential reflected effective RSV antagonism of IFN-mediated antiviral responses in infected cells. Our data are consistent with RSV non-structural proteins 1 and/or 2 perturbing the Jak-STAT signaling pathway, with concomitant reduced expression of antiviral effector molecules, such as MxA/B. Antagonism of Jak-STAT signaling was restricted to RSV-infected cells in WD-PBEC cultures. Importantly, our study provides the rationale to further explore IL-29 as a novel RSV prophylactic. Most respiratory viruses target airway epithelium for infection and replication, which is central to causing disease. However, for most human viruses we have a poor understanding of their interactions with human airway epithelium. Respiratory syncytial virus (RSV) is the most important viral pathogen of young infants. To help understand RSV interactions with pediatric airway epithelium, we previously developed 3-D primary cell cultures from infant bronchial epithelium that reproduce several hallmarks of RSV infection in infants, indicating that they represent authentic surrogates of RSV infection in infants. We found that RSV induced a potent antiviral state in these cultures and that type III interferon (IL-29) was involved. Indeed, our data suggest that IL-29 has potential to prevent RSV disease. However, we also demonstrated that RSV efficiently circumvents this antiviral immune response and identified mechanisms by which this may occur. Our study provides new insights into RSV interaction with pediatric airway epithelium.