A new study highlights a possible link between early-life viral infections and long-term respiratory health. IRR researchers and colleagues find that special proteins called MHCs, which help immune cells recognise and respond to threats, stayed elevated long after the initial infection. This suggests that lungs retain an enhanced ability to detect and process foreign material, triggering a faster and more effective immune response for subsequent infections, but potentially also promoting allergy development in susceptible people. Viral infections of the lung can reduce the severity of subsequent lung infections but can also increase the risk of asthma development in young children. How this happens is not known. Recent research in mice reveals that respiratory syncytial virus (RSV) infection, a common cause of coughs and colds, leaves a lasting imprint on lung epithelial cells - the thin layer of cells lining the airways. Traditionally regarded only as a physical barrier, these cells are now recognised as active participants in initiating immune responses.Here, IRR researchers, together with researchers at the Centre for Cardiovascular Science, CRUK Scotland Institute and University of Dundee, asked if viral infection of the lung leads to memory in lung lining (epithelial) cells, changing their responses to future infections and allergen exposure.In this study, mice infected with RSV, showed significant genetic and biochemical changes in these lung epithelial cells, twenty-eight days after infection - long after the virus had been cleared. After RSV infection, lung lining cells remember the virus, boosting their ability to fight future infections and may also trigger allergies or asthma. Further research is needed to confirm whether these changes also occur in humans and to identify any other alterations in lung epithelial cells following viral infection. Prof Jürgen Schwarze IRR Group Leader Many of these changes involved special proteins called major histocompatibility complexes (MHCs), which help immune cells recognise and respond to threats. Both types of MHC molecules stayed elevated long after the infection. This suggests that the lung epithelial cells retained an enhanced ability to detect and process foreign material, and to present it to immune cells, triggering a faster and more effective immune response.This ‘primed’ state may be beneficial, enabling faster and more effective responses to subsequent viral or bacterial challenges. However, it could also increase the likelihood of inappropriate immune activation against harmless environmental substances such as pollen or dust, potentially contributing to asthma or allergic airway disease in susceptible individuals.RSV is a leading cause of respiratory illness in young children and older adults. Understanding how it leaves a lasting ‘memory’ in the lung lining could help scientists figure out why some people recover without problems while others go on to develop asthma or other chronic lung issues. Further work will need to determine if such changes occur in people and if there are additional changes in lung epithelial cells after viral infection. This work was funded by the British Lung Foundation, Breathing Together Consortium, Medical Research Council and European Union.Read the full article in AllergySchwarze research group Tags CIR Publication date 19 Aug, 2025
