Polio Virus and Virus-Like Particles (IMAGE) University of Leeds Caption The attached image is an electron micrograph of live poliovirus particles (left) and empty particles (potential VLP vaccine) (right). The VLPs contain no infectious viral RNA and so the stain used to highlight them fills the empty space making them appear black. Credit University of Leeds Usage Restrictions None 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.