PROJECT SUMMARY: Human parainfluenza virus 3 (HPIV3) constitutes a major public health concern in the United States as it is the second largest cause of hospitalization in children under the age of five and responsible for high mortality in immunocompromised adults. Studying HPIV3 has traditionally been conducted using cell lines, small rodent models and human airway epithelial models, all of which have limitations with regards to their ability to provide insights into human disease in the lung. To address this gap in knowledge, we have developed a novel lung model using whole human lung tissue explants. In preliminary data, we utilized a recently developed GFP- tagged HPIV3 to infect human lung tissue and show that HPIV3 can replicate robustly in this system, as assessed by the presence of GFP-positive cells detected by flow cytometry. We hypothesize that evaluation of HPIV3 infection in this human lung tissue model will elucidate novel virus:host interactions and provide insights into the pathogenesis of HPIV3 in humans. In Aim 1, we will use GFP-tagged HPIV3 to infect human lung tissues to identify the infected cell types and evaluate the transcriptional changes induced by infection using single cell RNA sequencing. In Aim 2, we will characterize the inflammatory response induced by HPIV3 by examining the induction of chemokines/cytokines using multiplex ELISA, and identify the extent to which these inflammatory mediators that induce morbidity are produced from infected cells and/or bystander cells. These data will provide novel insights into how HPIV3 causes disease and have the potential to identify novel immunotherapeutic or antiviral targets. This project offers a unique training opportunity, as it meshes molecular cloning, traditional virology techniques, cutting edge single cell RNA sequencing technologies, translational research and high dimensional data analysis with thorough mentorship on how to become a successful academic scientist.