NOS2 and viral infectious disease: Previous studies have demonstrated that CF patients are more susceptible to infection by respiratory viruses such as human parainfluenza virus 3 (HPIV3) due to deficiencies in innate immune mechanisms in airway epithelial cells, including reduced activation of nitric oxide synthase 2 (NOS2) and 2’, 5’ oligoadenylate synthase 1 (OAS1) responses to viral infection [13].