NSF-ANR MCB/PHY: Virus self-assembly, from test tube to cell cytoplasm

Coming out of the most severe and destructive viral pandemic of the past 100-years, the importance of understanding how viruses “work” is clear. Most viruses – including polio, yellow fever, Dengue, and SARS, etc. – have RNA genomes that are quickly turned or “translated” into viral proteins in host cells that self-assembled into new virus particles called capsids.

Elucidating how this process happens is a high priority for preventing and treating these infections. This project sets out to connect in vivo experiments carried out in live cells with in vitro experiments carried out in a test tube with purified viral capsid proteins and RNA genome. While test tube studies allow for full control of the types and numbers of components and solution conditions in which they are interacting, live cells studies, on the other hand, involve viral RNA and capsid proteins in the presence of many unknown components whose effects on RNA translation and self-assembly into capsids have not yet been determined.

The fundamental understanding that results from this research will enhance the ability to develop anti-viral treatments. Graduate students will be trained in an inter-/cross-disciplinary range of physical, chemical, biological, and translational medicine concepts and methods. Active outreach efforts aim at enhancing interest and understanding of science amongst budding scientists and lay persons of all kinds will be conducted.

This project will be performed by an international collaboration between five different research groups in the US and France, each specializing in different experimental and theoretical techniques and each having extensive experience with one or the other of the plant (cowpea chlorotic mottle virus [CCMV]) and mammalian (hepatitis B [HepB]) viruses under study. These viruses were chosen because how significantly they differ in their host cell and capsid structure, so that general principles of viral self-assembly can be established.

It is the goal of this project to elucidate the differences between in vitro and in cellulo viral processes by progressively adding to RNA and capsid protein a series of molecules that play key roles in the viral “life” cycle, mimicking the crowded interior of the cell. Using cell-free cytoplasmic (ribosome-rich) extract, viral RNA will be translated into protein products and the time course of capsid assembly will be investigated by a combination of experimental techniques, including magnetic resonance, X-ray scattering, and fluorescence and electron microscopies.

Coarse-grained molecular dynamics computations and phenomenological theory will be used to analyze these kinetic data and to compare with what is learned using the same experimental techniques applied to corresponding virus assembly in test tubes, where all concentrations and solution conditions are controlled.

This collaborative US/France project is supported by the US National Science Foundation and the French Agence Nationale de la Recherche, where NSF funds the US investigator and ANR funds the partners in France.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.