Human metapneumovirus: understanding the molecular mechanisms and pathology of infection

Human metapneumovirus (HMPV) is a common and globally prevalent respiratory virus that can cause clinical symptoms ranging from mild respiratory illness to severe bronchiolitis and pneumonia, with substantial morbidity and mortality. HMPV accounts for a substantial health care and economic burden, with high hospitalization rates. Consequently, there is an urgent need for effective preventive and therapeutic interventions. The development of these interventions requires comprehensive knowledge of the virus's biology, including characteristics, epidemiology, evolution, virus-host interactions, and host immune responses. Despite being discovered nearly 25 years ago, HMPV has remained relatively underrecognized, resulting in limited awareness of its true impact and delays in the development of treatment options. Recent studies have demonstrated the emergence of novel genotypes and provided more insight into viral replication, spread, and host immune responses. In this review, we highlight the clinical significance of HMPV and explore the molecular mechanisms the virus employs throughout the course of an infection.