Liquid DNA behind virus attacks

New studies show viruses convert their DNA into liquid form to be injected into host cells, findings which could lead to new therapies that avoid resistance. In a previous study Dr Alex Evilevitch - a researcher at Lund University and Carnegie Mellon University - and his team found that DNA pressure inside a virus is five times higher than in an unopened champagne bottle. This pressure serves as a trigger that enables the virus to eject its DNA into a cell in the host organism. The same team of researchers, led by Evilevitch, have now successfully observed a phase transition from solid to fluid form at the moment of infection in a host cell. “The exciting part of this is that the physical properties of packaged DNA play a very important role in the spread of a viral infection, and those properties are universal,” said Evilevitch. “This could lead to a therapy that isn’t linked to the virus’ gene sequence or protein structure, which would make developing resistance to the therapy highly unlikely.” Evilevitch carried out two studies on different viruses (the herpes virus and bacteriophages), published in Nature Chemical Biology and PNAS. It was found that both undergo a temperature-dependent phase transition at 37°C, thought to be a direct adaptation to human body temperature. These two viruses separated at an early stage in evolution, several billion years ago. The fact that they both demonstrate the same ability to convert their DNA in order to facilitate infection indicates that this could be a conserved mechanism found in many types of virus. In both cases, the DNA is maintained in a rigid, glass-like state – due to electrostatic repulsion between chains - if the conditions are not right for infection. This ensures the DNA is not ejected at the wrong time. The team say understanding this regulatory mechanism may help researchers to come up with novel antiviral therapies that could block the phase transition and thus prevent infection. Solid-to-fluid DNA transition inside HSV-1 capsid close to the temperature of infection

Solid-to-fluid–like DNA transition in viruses facilitates infection

By Rebecca Dey