Distinctive Cytopathology of ECHO Viruses Types 22 and 23.

Summary The cytopathology of ECHO 22 and 23 was compared with other enteroviruses and found to be distinctive. The important differentiating features appeared in the nucleus. An eventual disappearance of the nucleolus and nuclear chromatin and a thickening and increase in staining intensity of the nuclear membrane resulted in appearance of an 'empty' nucleus. Seven isolates of ECHO 22 were found to have similar cytopathic changes. It is suggested that detailed study of the cytopathic effect of viruses in tissue culture may play an important role in relating new agents to the enterovirus group.