Structural basis for human respiratory syncytial virus NS1-mediated modulation of host responses

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. Overall design: 12 samples where analysed. A549 cell line was infected with mock, hRSV or mutated hRSV virus. Samples are: control mock-infected (2 replicas), hRSV wild-type NS1 infected (3 replicas), hRSV NS1 1-118 infected (3 replicas), hRSV NS1 L132A/L133A infected (2 replicas) and hRSV NS1 Y125A infected (2 replicas). Libraries was prepared for 96 h.p.i.

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Chatterjee S, Luthra P, Esaulova E, Agapov E, Yen BC, Borek DM, Edwards MR, Mittal A, Jordan DS, Ramanan P, Moore ML, Pappu RV, Holtzman MJ, Artyomov MN, Basler CF, Amarasinghe GK, Leung DW