Viral Diversity (image) University of Illinois at Urbana-Champaign Share Print E-Mail Caption The diverse physical attributes, genome sizes and lifestyles of viruses make them difficult to classify. A new study uses protein folds as evidence that viruses are living entities that belong on their own branch of the tree of life. Credit Julie McMahon Usage Restrictions Image may be used only to accompany stories about the research described in this release. Credit required: Julie McMahon. Share Print E-Mail 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.