Sustained Lung Inflammation Post-SARS-CoV-2 Infection in Mice Is Associated with Increased Pulmonary T Cells

Many SARS-CoV-2 patients experience chronic pulmonary symptoms and long-term inflammation despite viral clearance. While these clinical manifestations have been linked to the dysregulation of the adaptive immune response, the underlying immunopathology remains poorly understood due to a lack of suitable animal models. To investigate long-term pulmonary consequences of SARS-CoV-2 infection, we used a genetic cross of 129 mice and C57BL/6 (B6)-K18-hACE2 transgene mice, a model previously shown to survive infection. 129xB6-K18-hACE2 mice or littermate controls were infected with a low dose (5 × 10² PFU) of ancestral SARS-CoV-2. Complete viral clearance and full recovery from weight loss occurred by day 8 post-infection. However, prolonged inflammation in the lung and airways persisted up to day 28 post-infection and was associated with the presence of CD4⁺ and CD8⁺ T cells, particularly CD8⁺ effector T cells. This model may therefore prove valuable for further understanding of drivers of long-term lung inflammation and for testing therapeutic strategies and clinically relevant interventions that can target long-term pulmonary inflammation following SARS-CoV-2 infection.