SARS virus particles. Coloured transmission electron micrograph (TEM) of two SARS virus particles (green). Severe acute respiratory syndrome (SARS) is a fatal lung disease that first appeared in China in 2002. The SARS virus is a coronavirus. The coronaviruses take their name from their crown (corona) of surface proteins, which are used to attach to and penetrate their host cells. Once inside a cell, the virus particles use the cell machinery to make more copies of themselves. Magnification: x176,000 when printed 10cm high.