False-colour transmission electron micrograph (TEM) of red blood cells (top, red) being adsorbed onto surface of a cell (orange, green vacuoles) infected with the enteric coronavirus, responsible for common cold & gastroenteritis in humans. Virus particles (virions) appear as small red dots between the cell wall and the red blood cells. Corona virus particles are able to agglutinate red blood cells due to presence of a specific glycoprotein (haemagglutinin) in the viral wall. Haemadsorption occurs at the stage of viral replication when the viral haemagglutinin is concentrated in host cell's plasma membrane. Magnification: X 1500 at 35mm.