Unveiling how the genome has condensed itself inside the virus

"The motivation for the study is viral replication," says the director of the project, Associate Professor Juha Huiskonen from the Helsinki Institute of Life Science Hilife.

The breakthrough results were achieved using cryogenic electron microscopy, a method that has recently been revolutionized structural biology – a field of biology that aims to understand how molecules of life work at the atomic level.

Using powerful electron microscopes, the team has been working on images of highly purified viruses. The images were then combined into three-dimensional models, allowing the scientists to not only see the proteins that make up the shell of the virus, but also, for the first time, to trace the nucleic acid genome inside the protein shell. The genome has been seen to form a liquid crystal, a highly condensed and ordered state of matter that is still fluid.

"The degree of condensation is remarkable." To illustrate, if the virus was the size of an exercise ball and the viral genome was thick, there would be almost 70 meters of such rope stuffed inside the ball, "Huiskonen says.

The fluidity of the genome may be required to permit the expression of the viral genes in the confines of the viral capsid, but it is still an open question how the genome virus does not get entangled in the process. In a follow-up study the team aims to address this very issue.

"Explains Minna Poranen, a university lecturer from the Faculty of Biological and Environmental Sciences of the University of Helsinki.

"When the viruses are carrying their work, they can be observed at different states." This way we can gain an even better understanding of how these fascinating nanomachines function, "adds Huiskonen.

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