HPV16 (IMAGE) Penn State Caption These are the Cryo-EM micrograph of HPV16 particle capsids -- outer shell. A shows virus particles as they are, B shows them after infusion of heparin. Credit Susan Hafenstein, Penn State Usage Restrictions Non commercial use only 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.