Norovirus is highly contagious and very difficult to control. In general, the Norovirus epidemic broke out in hospitals, nursing homes, schools, hotels, and cruise ships. Calicivirus, including Norovirus and sapovirus, is also an important animal pathogen, leading to ‘cat flu’ associated with high mortality in domestic cats. In a new study, British researchers used cryo-electron microscopy to study the structure of the feline calicivirus that causes cat flu to better understand how the virus family initiates infection. The relevant research results are published in the journal of Nature.

These researchers found that the virus undergoes structural changes after binding to the surface of host cells, leading to the formation of a funnel-like structure on the surface of the virus particles. This structure is thought to be inserted into the cell membrane, allowing the virus to inject its genome into the host cell and initiate its infection process. An in-depth understanding of the early stages of calicivirus infection provides new targets for the development of antiviral drugs against this viral family.

 

 

Dr. David Bhella, the leader of this study, said, “When a virus infects us, it binds and invades our cells. This usually happens through a process called ‘endocytosis’. And cells use this process to ingest nutrients from their environment.” The virus triggers endocytosis, causing the host cell to bring the viral particles into the cell in the form of bubbles or vesicles called endosome. The virus then needs to detach from the endosome, release its genes into the cells and initiate infection.

 

Dr. Bhella said, “Furthermore, we calculated an atomic model of a portal protein called VP2. Although VP2 is known to be essential for the production of infectious viruses, its function has not been determined so far. We found that VP2 is assembled into a funnel-like structure that may cause the inner body to escape, which represents an important step in understanding the Calicivirus family and viruses containing icosahedral RNA.”

 

 

 

Reference

Michaela J. Conley et al. Calicivirus VP2 forms a portal-like assembly following receptor engagement, Nature (2019). DOI: 10.1038/s41586-018-0852-1.