Paramyxoviruses: Parainfluenza Viruses

Abstract

Human parainfluenza viruses (HPIVs) are a group of respiratory viruses that cause human diseases including bronchitis, croup, bronchiolitis, and pneumonia in infants, children, and immunocompromised individuals. HPIVs, in combination with influenza virus and respiratory syncytial virus, are responsible for the majority of respiratory viral infections that require medical attention. These viruses were first described in 1956; longitudinal studies of community and family HPIV disease were carried out during the twentieth century. More recently, HPIV has been recognized as an important and serious cause of pneumonia in immunocompromised patients and an important etiology of lower respiratory tract disease in people of all ages. Epidemiologic studies documenting the importance of HPIVs have been mainly conducted in developed countries, but new sensitive molecular diagnostic tools are being utilized to further characterize HPIV disease in diverse populations worldwide. In recent years, the molecular mechanisms of paramyxovirus cell entry and replication are becoming better understood. Paramyxoviruses enter the target cell by binding to a cell surface receptor and then fusing the viral envelope with the target cell membrane, allowing the release of the viral genome into the cytoplasm. Binding and fusion are driven by viral fusion machinery consisting of the receptor-binding protein and the fusion protein. Better understanding of these crucial steps may help advance the development of antiviral therapies. No effective HPIV therapies are currently available, but new HPIV vaccines and antivirals are currently being actively studied in children and immunocompromised individuals.