Scanning electron micrograph (SEM) of a human alveolar basal epithelial cell (A549 cell line) infected with Human adenovirus strain J.J. subtype D/10 (HAdV-10) virus. The cell has been infected with HAdV-10 for 3 days and is in the process of undergoing lysis, releasing intracellular synthesised viral particles through pores in the plasma membrane (100nm yellow particles). Adenoviruses are a group of viruses that can cause mild to severe infection throughout the body. Adenovirus infections most commonly affect the respiratory system, eyes, and the gastrointestinal tract. These infections can cause symptoms similar to the common cold and flu or pneumonia, conjunctivitis, or acute gastroenteritis. Most adenovirus infections are mild. Magnification: x10000 when printed 10 centimetres wide. Specimen courtesy of Virology Research Services Ltd (Scott Lawrence).