Figure 2. Detection of viral proteins and viral RNA associated with intracytoplasmic virions. A) Immunogold labeling of viral proteins by using hyperimmune mouse ascitic fluid directed against severe acute respiratory syndrome–associated coronavirus (12 nm gold). B) Ultrastructural in situ hybridization detection of viral RNA by using a pool of polymerase and nucleocapsid riboprobes (6 nm gold). Bars, 100 nm.