Project description:Human respiratory syncytial virus (hRSV) is a major cause of morbidity and mortality in the pediatric, elderly, and immune compromised populations. A gap in our understanding of hRSVdisease pathology is the interplay between virally encoded immune antagonists and host components that limit hRSV replication. hRSV encodes for non-structural (NS) proteins that are important immune antagonists; however, the role of these proteins in viral pathogenesis is incompletely understood. Here we report the crystal structure of hRSV NS1 protein, which suggests that NS1 is a structural paralog of hRSV matrix (M) protein. Comparative analysis of the shared structural fold with M revealed regions unique to NS1. Studies on NS1 WT or mutant alone or in recombinant RSVs demonstrate that structural regions unique to NS1 contribute to modulation of host responses, including inhibition of type I IFN responses, suppression of dendritic cell maturation, and promotion of inflammatory responses. Transcriptional profiles of A549 cells infected with recombinant RSVs show significant differences in multiple host pathways, suggesting that NS1 may have a greater role in regulating host responses than previously appreciated. These results provide a framework to target NS1 for therapeutic development to limit hRSV associated morbidity and mortality.
Project description:Human respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infections in young children, the elderly, and immunocompromised individuals. Prior exposure to RSV affords little protection and many are susceptible to reinfection throughout life. Virally encoded non-structural (NS) protein 1 (NS1) is thought to modulate host responses in the cytosol. Here, we describe the nuclear localization of NS1 during RSV infection and a corresponding nuclear role in modulating host transcription. In support, we show that a significant proportion of NS1 is partitions to the nucleus and that NS1 alone is necessary and sufficient to translocate into the nucleus. NS1 co-localizes with exportin XPO1 and inhibition of XPO1 results in NS1 accumulation in the nucleus. Furthermore, nuclear NS1 is chromatin-associated and co-immunoprecipitates with Mediator complex proteins. Chromatin-immunoprecipitation demonstrates enrichment of NS1 binding overlapping Mediator and interferon-stimulated transcription factor binding sites that lie within regulatory elements of genes differentially expressed during RSV infection. Mutation of the unique alpha helix in NS1 enhances its repressive effect on host gene expression. Together, these data suggest that nuclear NS1 may alter host responses to RSV infection by binding at the promoters and enhancers of host immune response genes and disrupting host transcriptional regulators. Our study identifies yet another regulatory layer of interactions with RSV proteins that shapes host response to RSV and potentially impacts long-term immunity to RSV.
Project description:Human respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infections in young children, the elderly, and immunocompromised individuals. Prior exposure to RSV affords little protection and many are susceptible to reinfection throughout life. Virally encoded non-structural (NS) protein 1 (NS1) is thought to modulate host responses in the cytosol. Here, we describe the nuclear localization of NS1 during RSV infection and a corresponding nuclear role in modulating host transcription. In support, we show that a significant proportion of NS1 is partitions to the nucleus and that NS1 alone is necessary and sufficient to translocate into the nucleus. NS1 co-localizes with exportin XPO1 and inhibition of XPO1 results in NS1 accumulation in the nucleus. Furthermore, nuclear NS1 is chromatin-associated and co-immunoprecipitates with Mediator complex proteins. Chromatin-immunoprecipitation demonstrates enrichment of NS1 binding overlapping Mediator and interferon-stimulated transcription factor binding sites that lie within regulatory elements of genes differentially expressed during RSV infection. Mutation of the unique alpha helix in NS1 enhances its repressive effect on host gene expression. Together, these data suggest that nuclear NS1 may alter host responses to RSV infection by binding at the promoters and enhancers of host immune response genes and disrupting host transcriptional regulators. Our study identifies yet another regulatory layer of interactions with RSV proteins that shapes host response to RSV and potentially impacts long-term immunity to RSV.
Project description:Human respiratory syncytial virus (RSV) is the leading cause of severe acute lower respiratory tract infections in infants worldwide. Non-structural protein NS1 of RSV modulates the host innate immune response by acting as an antagonist of type I and type III interferon (IFN) production and signaling in multiple ways. It is likely that NS1 performs this function by interacting with different host proteins. In order to obtain a comprehensive overview of NS1 interaction partners, we performed three complementary protein-protein interaction screens i.e. BioID, MAPPIT and KISS. The BioID proximity screen was performed during an RSV infection in A549 cells. MED25, a subunit of the Mediator complex, was identified in all 3 performed screening methods as a potential NS1 interacting protein. We confirmed the interaction between MED25 and RSV NS1 by co-immunoprecipitation, not only upon overexpression of NS1, but also with endogenous NS1 during RSV infection. We also demonstrate that the replication of RSV is enhanced in MED25 knockout A549 cells, suggesting a potential antiviral role of MED25 during RSV infection. Mediator subunits function as transcriptional coactivators and are involved in transcriptional regulation of their target genes. Therefore, the interaction between RSV NS1 and cellular MED25 might be beneficial during an RSV infection as this can affect host transcription and the host immune response to infection.
Project description:Influenza A virus (IAV), one of the most prevalent respiratory diseases, causes pandemics around the world. The multifunctional non-structural protein 1 (NS1) of IAV is a viral antagonist that suppresses host antiviral response. However, the mechanism by which NS1 modulates the RNA interference (RNAi) pathway remains unclear. Here, we identified interactions between NS1 proteins of Influenza A/PR8/34 (H1N1; IAV-PR8) and Influenza A/WSN/1/33 (H1N1; IAV-WSN) and Dicer’s cofactor TAR-RNA binding protein (TRBP). We found that the N-terminal RNA binding domain (RBD) of NS1 and the first two domains of TRBP protein mediated this interaction. Furthermore, two amino acid residues (Arg at position 38 and Lys at position 41) in NS1 were essential for the interaction. We generated TRBP knockout cells and found that NS1 instead of NS1 mutants (two-point mutations within NS1, R38A/K41A) inhibited the process of microRNA (miRNA) maturation by binding with TRBP. PR8-infected cells showed masking of short hairpin RNA (shRNA)-mediated RNAi, which was not observed after mutant virus-containing NS1 mutation (R38A/K41A, termed PR8/3841) infection. Moreover, abundant viral small interfering RNAs (vsiRNAs) were detected in vitro and in vivo upon PR8/3841 infection. We identify, for the first time, the interaction between NS1 and TRBP that affects host RNAi machinery.
Project description:Diagnosis of acute respiratory viral infection is currently based on clinical symptoms and pathogen detection. Use of host peripheral blood gene expression data to classify individuals with viral respiratory infection represents a novel means of infection diagnosis. We used microarrays to capture peripheral blood gene expression at baseline and time of peak symptoms in healthy volunteers infected intranasally with influenza A H3N2, respiratory syncytial virus or rhinovirus. We determined groups of coexpressed genes that accurately classified symptomatic versus asymptomatic individuals. We experimentally inoculated healthy volunteers with intranasal influenza, respiratory syncytial virus or rhinovirus. Symptoms were documented and peripheral blood samples drawn into PAXgene tubes for RNA isolation.
Project description:Transcriptional responses in lungs of mice infected with Respiratory Syncytial Virus (RSV) were compared to a control and mock infections
Project description:Stimulation of unmyelinated C-fibers is able to initiate host responses. In this study, we established the model of C fiber degenerated (KPCF) mice. KPCF mice were given respiratory syncytial virus (RSV) infection. We aimed to figure out the role of C fibers in RSV infection.
Project description:To study the role of Dengue virus serotype 4 NS1 in modulation of host cell transcriptome we performed gene expression profiling using data obtained from RNA- sequencing of total RNA from 3 different samples: Huh7 cells (no transfection), Huh7 cells transfected with pTracer-SV40 empty vector and Huh7 cells transfected with pTracer-SV40 encoding dengue virus serotype 4 NS1 (pDENV4 NS1).
Project description:Influenza A virus (IAV) is an important human respiratory pathogen that causes significant seasonal epidemics and potential devastating pandemics. As part of its life cycle, IAV encodes the multifunctional protein NS1, that, among many roles, prevents immune detection and limits interferon (IFN) production. As different host immune pathways exert different selective pressures against IAV as replication progresses, we expect a prioritization in the host immune antagonism by NS1. In this work, we profiled bulk transcriptomic differences in a primary bronchial epithelial cell model facing IAV infections at distinct NS1 levels. We further demonstrated that the intracellular NS1 levels in-part shapes the host response heterogeneity at single cell level. We found that modulation of NS1 levels reveal a ranking in its inhibitory roles: modest NS1 expression is sufficient to inhibit immune detection, and thus the expression of pro-inflammatory cytokines (including IFNs), but higher levels are required to inhibit IFN signaling and ISG expression. Lastly, inhibition of chaperones related to the unfolded protein response requires the highest amount of NS1, often associated with later stages of viral replication. This work demystifies some of the multiple functions ascribed to IAV NS1, highlighting the prioritization of NS1 in antagonizing the different pathways involved in the host response to IAV infection.