Cytomegalovirus Particles (image) University of Arizona Caption These are cytomegalovirus particles as seen through an electron microscope. While some of the protein capsules are empty, others contain tightly packaged DNA, visible as dark structures. The diameter of a human hair would cover a line of about 600 virus particles. Credit Farah Bughio, Felicia Goodrum Usage Restrictions This visual may only be used in conjunction with reporting/posting of this news release. Image/video credit must be included exactly as indicated. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.