| Description |
Human parainfluenza viruses, which belong to the paramyxovirus family, are pleomorphic viruses whose envelope is derived from the last host cell they infected. They comprise a group of four distinct serotypes of single-stranded RNA viruses. Human parainfluenza virus type 1 is the most common cause of croup and other upper and lower respiratory tract illnesses. Human parainfluenza virus type 2 infections usually follow type 1 infections and also cause croup and other upper and lower respiratory tract illnesses, and may cause aseptic meningitis and parotitis. Human parainfluenza virus type 2 forms filamentous particles in virus-infected, polarized epithelial cells. Human parainfluenza virus type 3 infections are associated with pneumonia as well as bronchiolitis and typically last longer than type 1 and 2 infections. Human parainfluenza virus type 4, one of the rubulaviruses, has a V protein with a highly conserved cysteine-rich domain characteristic of paramyxovirus V proteins. It is th |
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