CD80 and viral infectious disease: Since viral infections trigger interferon-induced gene expression in epithelial cells to orchestrate immune responses (Schleimer et al., 2007), we also stained for co-stimulatory molecules CD80 and CD86 (Kaneko et al., 2000), or immune-activating molecules CEACAM5 and CEACAM6 (Lambrecht and Hammad, 2010).