Human metapneumovirus: Insights into immune evasion, pathogenesis and liposome-based vaccine strategies.

Human Metapneumovirus (HMPV) remains a major contributor to respiratory diseases, particularly affecting infants, the elderly, and immunocompromised individuals. HMPV, first identified in 2001, has been a prominent cause of respiratory tract infections, ranging from mild upper respiratory symptoms to severe pneumonia and bronchiolitis. Despite its impact, there are currently no licensed vaccines or specific antivirals treatments targeting HMPV. The virus evades host immunity by suppressing interferon signaling through pathways such as RIG-I/MAVS and JAK-STAT, and by impairing dendritic cell maturation, which collectively delays adaptive immunity. Vaccine development efforts focus on live-attenuated, subunit, viral vector-based, and mRNA platforms, with the F protein identified as the primary target for eliciting neutralizing antibodies. Advancements such as lipid nanoparticles and virus-like particles have enhanced vaccine delivery and immunogenicity. Understanding HMPV-host immune interactions is essential for reducing the global disease burden and advancing both novel preventive and therapeutic interventions. This review consolidates current knowledge on HMPV virology, immune evasion, and vaccine development while highlighting emerging diagnostic innovations and multivalent vaccine platforms. Global research collaboration remains crucial in combating HMPV-related respiratory diseases and improving preventive strategies. Future directions emphasize to develop multivalent vaccines against multiple respiratory viruses, the optimization of adjuvants, and the deployment of modular vaccine platforms to address antigenic variability.