IL13 and airway hyperresponsiveness: RV infection of 6 day-old mice, but not mature mice, induces type 2 airway inflammation, mucous metaplasia and airways hyperresponsiveness (8) which is associated with expansion of IL-13-producing type 2 innate lymphoid cells (ILC2s) and dependent on the innate cytokines IL-25, IL-33 and TSLP (9, 10).