Cytological and cytochemical studies of HeLa cells infected with adeno-viruses

The sequential morphological and cytochemical alterations in HeLa cells infected with adenovirus types 1 to 4 are described. Each of the four viruses studied led to consistent and reproducible cytological changes not observed in uninfected control cultures. All four agents produced striking and characteristic changes in the nuclei of infected cells. Alterations in the cytoplasm, though present, were less marked, particularly in the early stages of infection. In cells infected with type 1 or 2 adenovirus, rounded intranuclear inclusions which progressed from eosinophilic and Feulgen-negative to basophilic and Feulgen-positive, together with a homogeneous glassy, Feulgen-positive nuclear background, were prominent features. Cells infected with type 3 or 4 adenovirus exhibited marked rearrangement of basophilic nuclear material and sharply defined crystal-like inclusions, predominantly intranuclear in location, which also varied from Feulgen-negative to positive. In terms of detailed cytological effects, therefore, the four agents could be divided into two subgroups, viz., types 1 and 2 on the one hand and types 3 and 4 on the other. Measurement of DNA in individual nuclei by means of Feulgen microspectrophotometry revealed the values in infected cells to be increased above the levels of the uninfected controls.