Temporal transcription analysis of innate immune response to respiratory syncytial virus infection (VIR2P.1164)

Abstract Respiratory syncytial virus (RSV) is a leading cause of severe respiratory disease in infants. Little is known about the cell-intrinsic innate immune responses of RSV infected epithelial cells or responding immune cells. We studied two clinical-isolates from the RSV-B subgroup: NH1125 that induces high cytokine responses (measured by CCL5 and IL-6); and NH1067, which induces low cytokine responses. We used RNA sequencing technologies to profile the transcriptome of non-immune and immune-lineage cells following infection with these two strains. The innate immune response of A549, a human epithelial cell line, was distinct from that of monocyte-derived macrophages and dendritic cells at 2, 4, 8, and 24 hours following infection. These responses were compared at a high multiplicity of infection (MOI=5) for a homogeneous response and low MOI (MOI=0.3), which more closely resembles in vivo conditions, to determine the extent of communication between infected and un-infected cells. Our analyses revealed 6 classes of genes marking the early- and late-stage cellular responses. Pathway analyses identified miRNA let-7f, EIF2 signaling and mitochondrial dysfunction signaling as early activated pathways and pattern-recognition receptor and Interferon pathway at later time points. A cross-comparison also reveals that RSV gene expression and viral replication is greater in A549 cells than macrophages, consistent with a more potent cell-intrinsic innate defense in myeloid lineage cells.