However, at the late stage of infection (9 dpi), while lung inflammation of WT mice had gradually regressed, lung pathology in IL-1R1-/- mice was aggravated and resulted in lung damage and edema, characterized by alveolar structure disruption and hyaline membrane formation in the lung parenchyma as well as congestion and swelling of the lung interstitium. This evidence concerns the gene IL1R1 and infection.