Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infections (LRTIs) in children worldwide. RSV infection rapidly generates reactive oxygen species (ROS) that produce oxidative DNA damage, with 8-oxoguanine (oxoG) being one of the most abundant. OxoG is repaired by the 8-oxoguanine DNA glycosylase1 (OGG1)-initiated DNA base excision repair pathway (BER). We have documented that ROS transiently inactivates OGG1 enzymatic activity, leading to formation of an OGG1-DNA complex in inducible gene promoters and in close proximity to NFκB-binding motifs. We have also demonstrated that: 1) OGG1- DNA complex at oxoG increases NFκB binding in vitro; and 2) OGG1 depletion or inhibition of OGG1 substrate binding by highly selective small molecules result in decrease NFκB-dependent gene expression in vivo. These data indicate that the OGG1-oxoG complex plays a key role in the innate immune response (IIR). As such, we recently found that OGG1 is required for RSV-induced expression of innate chemokines, cytokines, and interleukins constituting the IIR. Related to the overall theme of this P01, we have also shown that repeated activation of OGG1-dependent innate pathways resulted in modulation of gene networks controlling the actin cytoskeleton, extracellular matrix, cell adhesion, and cell junction apparatus, resulting in airway remodeling. Because of the high specificity of OGG1 for oxoG, these results point to a novel paradigm wherein oxoG functions as an epigenetic element that plays a central role in the regulation of genes that link IIR to airway remodeling. The overarching hypothesis of this project is that the RSV-induced oxidation of guanine to oxoG in gene regulatory regions is an epigenetic modification that links inflammation with airway remodeling via the NFκB pathway. This hypothesis will be tested in three Specific Aims: 1) RSV-induced pro-inflammatory gene expression and acute inflammation is dependent on ROS-induced oxidative damage to DNA and OGG1; 2) The OGG1 DNA complex at·oxoG in the proximal promoter regions of IIR genes serves as a platform for NFκB binding occupancy in response to RSV infection; 3) The OGG1·DNA complex links chronic oxidative stress with tissue remodeling in RSV-primed mice in response to allergen challenges. To achieve these aims, we will utilize mouse models, primary human small airway epithelial cells, nasopharyngeal cells isolated from RSV-infected infants, and well as state-of-the-art molecular technologies. Our studies contribute to the understanding of the role of the RSV-ROS-induced OGG1-DNA complex at oxoG in epigenetic regulation of NFkB-driven expression of IIR and airway remodeling genes in the context of RSV LRTI. This work will also advance innovative approaches for treatment of LRTI using available small-molecule inhibitors of OGG1.