Morphological Studies on the Replication of a Defective Satellite Virus and its Helper Adenovirus

The defective adeno-satellite virus replicates only when cells are co-infected with a “helper” adenovirus. Following simultaneous infection of green-monkey-kidney cells with a simian adenovirus and its satellite, changes in the nucleic acid patterns of infected cells were detectable by acridine orange staining within 12 hours. Diffuse, homogeneous, green inclusions that could be distinguished from the discrete, large, yellow inclusions produced by adenovirus alone were observed. Fluorescein-labeled antisatellite antiserum and rhodamine-labeled antiadenovirus antiserum were used to detect the sites of replication of the two viruses. Both antigens were clearly demonstrated in the same nucleus of many infected cells, as indicated by the development of separate yellow-green and orange inclusions. However, most nuclei showed strong fluorescence of a single color—an indication that in nuclei where large amounts of satellite capsid antigens were detectable, the amount of adenovirus antigen was markedly reduced and vice versa. Electron microscopic examination of companion ultrathin sections confirmed these observations.