Colorized transmission electron micrograph of an HIV-1 virus particle (red/yellow) budding from the plasma membrane of an infected H9 T cell (blue). Image by the National Institute of Allergy and Infectious Diseases (NIAID), USA, captured at the NIAID Integrated Research Facility in Fort Detrick, Maryland, USA; image modified by MIC. The cover is published under the Creative Commons Attribution (CC BY) license.