Details : Coronaviruses are large, enveloped RNA viruses. The human coronaviruses cause common colds, may cause lower respiratory tract infections, and have been implicated in gastroenteritis in infants. Novel coronaviruses have been identified as the cause of severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). Animal coronaviruses cause diseases of economic importance in domestic animals. Coronaviruses of lower animals establish persistent infections in their natural hosts. The human viruses are difficult to culture and therefore are more poorly characterized.