Respiratory syncytial virus (RSV) particles,coloured transmission electron micrograph (TEM). This pneumovirus,a type of paramyxovirus,is a major cause of human respiratory tract infections in patients of all ages. Each virion consists of RNA (ribonucleic acid) genetic material enclosed in a protein coat,or capsid (orange),within a phospholipid envelope (cream). The envelope is covered in protein spikes (green),which enable the virus to attach to and enter a host cell. In adults,RSV only affects the upper respiratory tract,but in infants bronchiolitis (bronchiole inflammation) or bronchopneumonia can result. Magnification: x118,000 when printed 10 centimetres wide |