Capsid formation (IMAGE) University of California - Riverside Caption From left to right: The green triangles mimic capsid proteins. In the absence of a viral genome, they assemble around smaller segments of RNA. However, the shell is stressed and can be easily broken into pieces. The color bar shows the different levels of stress. Once the viral RNA is available, the capsid proteins start to leave non-viral RNAs and assemble around the viral genome. This can be done relatively easily because of the high stress level of capsid proteins in the smaller shell. The right figure shows capsid proteins assembled around the native RNA, forming a stable icosahedral shell. Credit Zandi lab, UC Riverside. Usage Restrictions None. License Original 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.