Infection of mature BALB/c mice with the A2001/2-20 isolate causes more weight loss, dyspnea, IL-13 and Gob5 expression, epithelial desquamation, bronchiolitis, mucus metaplasia and airway hyperresponsiveness than the other strains, while showing fewer IFN-γ expressing CD8+ T cells, which function to suppress RSV-induced Th2 responses [65]. The gene discussed is IL13; the disease is infection.