Early-life respiratory syncytial virus infection and asthma.

Respiratory infections during critical periods of lung development can shape immune responses and cause lasting alterations in pulmonary structure and function. Lung development begins in utero, with airway branching, alveolarisation and epithelial differentiation continuing postnatally, making the lungs particularly vulnerable to early-life insults. Early-life respiratory syncytial virus infections are a major cause of severe respiratory diseases. Furthermore, risks are amplified by preterm birth and specific maternal environmental exposures. In this review, we discuss how early-life respiratory syncytial virus infection can disrupt normal lung development, predisposing to recurrent wheeze, asthma and other chronic lung diseases. We also discuss mechanistic studies, demonstrating how pathogenesis involves a complex interplay between epigenetic regulation, immune activation and airway remodelling. Finally, we highlight preclinical models that have provided some mechanistic insights into the determinants of lung health outcomes and the urgent need for better translational models to gain a deeper understanding of these processes. The intent of this review is to create impetus for developing targeted preventative and therapeutic strategies to mitigate the long-term impact of early-life viral infections on respiratory health.