Abstract Introduction/Rationale of the study Respiratory syncytial virus (RSV) is the leading cause of respiratory tract infections, in children worldwide. While new neutralizing antibody strategies are available to prevent severe RSV airway disease, no vaccine or specific pharmacologic treatment exists to cure RSV infection in infants. Innate immune mediators such as cytokines produced by respiratory epithelial cells in response to RSV infection, have been detected in airway secretions of RSV-infected patients. Extracellular vesicles (EVs), cell-derived nanoparticles that transfer proteins and other bioactive molecules, can modulate recipient cell behavior. The nasal epithelium is a primary site of RSV entry, but the inflammatory cargo of EVs from the upper airways during infection has not been characterized. Here, we report the first detection of inflammatory proteins in EVs from nasopharyngeal secretions of RSV-positive children using a highly sensitive proteomic platform targeting 248 inflammatory markers. Methods We collected NPS samples from children with RSV infection. EVs were isolated from NPS samples positive or negative for RSV. EVs were purified using a two-step enrichment method and characterized using particle sizing (size and concentration) and Exocheck array for the EV markers. Using the novel NULISAseq Inflammation Panel technology, we profiled inflammatory proteins in EVs and NPS samples. Differential expression of biomarkers in EVs, NPS, both, or neither was assessed using the R Studio package. Results As per the guidelines of the International Society of Extracellular Vesicles, we measured EV size, particle number, and EV markers to confirm the purity and identity of EVs isolated from NPS samples. We identified twenty-nine common markers in both EVs and NPS, including BST2, CSF3, CXCL8, IL19, MMP8, and S100A12, as well as 176 markers present only in NPS. Conclusions Identifying inflammatory mediators in NPS and EV samples contributes to understanding the mechanisms of virus-mediated pathogenesis in RSV infections, discriminating against the severity of disease following RSV infection, and supporting the future development of EV-based strategies to prevent RSV disease. This abstract is funded by: R25HL161715; Parker B. Francis Fellowship Program; American Lung Association (ALA); P01 AI062885
Corsello-Gorgun et al. (Fri,) studied this question.