TLR4 and influenza: We also found that PSNs express receptors for cellular components specific to bacteria (Tlr4, Tlr5, Nod1, and Naip1), cell surface proteins that enable entry of respiratory viruses (e.g., Uvrag for influenza, Igf1r for respiratory syncytial virus (RSV), and Pvrl4 for measles), and intracellular RNA and DNA sensors (Ddx58, Dhx58, Ddx41, Lrrfip1 and Aim2), suggesting they can direct detect or be influenced by pathogens (Figure S3B and S3C).