Using selective β2-AR agonists and antagonists or genetic ablation of the receptor, several laboratories have described the role that β2-AR signaling pathways play in infection with different bacterial (L. monocytogenes, P. aeruginosa, S. typhimurium, K. pneumonia, E. coli) or viral pathogens (Cytomegalovirus, Herpes simplex, Influenza, Vesicular stomatitis) [21, 114]. This evidence concerns the gene ADRB2 and influenza.