The Occurrence of Intranuclear Crystals in Living HeLa Cells Infected with Adenoviruses

In a recent study of the sequential changes produced by adenoviruses in HeLa cells, Boyer et al. (I) reported the presence of deoxyribonucleic acid (DNA) containing crystals after infection with adenoviruses type 3 and type 4. These findings confirm observations reported by other investigators (2-5). In order to exclude the possibility that the crystals might have resulted from fixation or other processes involved in preparing the material for light and electron microscope studies, living cultures were examined under the phase and interference microscopes. In this study, two series of tissue cultures of HeLa ceils were grown on coverslips. One was infected with adenovirus type 3 and the other with adenovirus type 5. As reported previously (I), none of the control cultures showed any crystals, but the cells infected with the adenoviruses revealed the presence of well defined crystals. These crystals were located predominantly in the nuclei and to a lesser extent in the cytoplasm. The appearance of the crystals in fresh, unfixed, and unstained cells as seen under the interference microscope is illustrated in the accompanying photographs. Figs. 1 and 2 are photographs of cultures infected with adenovirus type 3;