Maturing Retrovirus (IMAGE) European Molecular Biology Laboratory Caption The role and shape of the protein shell (blue/orange) changes from the immature (top) to the mature form of the virus (bottom). Credit EMBL/T.Bharat Usage Restrictions EMBL press and picture releases including photographs, graphics, movies and videos are copyrighted by EMBL. They may be freely reprinted and distributed for non-commercial use via print, broadcast and electronic media, provided that proper attribution to authors, photographers and designers is made. License Licensed content 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.