Norovirus is a major causative virus of viral acute gastroenteritis that is prevalent all over the world, and has caused several outbreaks in Japan, which has become a major social problem.However, since the cells that can culture norovirus are very limited and there is little structural knowledge about the virus, there is still no efficient treatment or vaccine.

　Therefore, the research group investigated the structure of norovirus particles in detail using a device called a cryo-electron microscope.As a result, it was discovered that mouse norovirus has two different particle structures of the same species. The two structures were found to switch between changing the pH of the solution and the concentration of metal ions such as calcium.Experiments have shown that one type is a non-infectious structure that is less susceptible to cell infection and the other is an infectious type.

　The research group attributed the existence of these two structures to avoiding the immune system.Norovirus invades through the mouth of animals, passes through the stomach without being digested, and infects cells of the small intestine.Therefore, it is thought that the non-infectious structure usually deceives this immune system to approach the cells of the target small intestine, and finally transforms into an infectious structure to infect.

　This time, the two structures of human norovirus were confirmed for the first time in the same strain (GII.2 strain), but it is still unknown how the structures are switched.Future research is expected to clarify the structural changes and infection mechanism of human norovirus, leading to the development of therapeutic agents and vaccines.

Paper information:[PLOS Pathogens] Dynamic rotation of the forming domain enhances the infectivity of norovirus