Viral Assembly of the SARS-CoV-2 virus - NanoBiology Course 2020 - Tuesday Group
Channel: Maastricht4Imaging
Date: 02/11/2020

In this video students of the Maastricht Science Program NanoBiology Course 2020, show their explanation of the SARS-CoV-2 viral assembly. Using CellPAINT, UCFS Chimera and their creativity they explain the nanobiology of how the SARS-CoV-2 virion can form within a cell. 

Viruses are not living things. They are just complicated assemblies of molecules, in particular macromolecules such as proteins, oligonucleotides, combined with lipids and carbohydrates. A virus cannot function or reproduce by itself. It needs a host cell.

When a virus enters the host cell, a series of chemical reactions occur that lead to the production of new viruses. A virus needs to find a host cell, attach to it, enter it, and reprogram it such that it will replicate its genome and produce new proteins that allow the assembly of a new virus. The genome of a virus codes for a very limited set of proteins. Some of these proteins are used to reprogram the cell, play a role in the replication, or act upon the cell's defense mechanism against intruders such as viruses. These proteins are called the non-structural proteins. The viral genome also codes for a set of structural proteins: these are the proteins that, together with the viral genome, lipids and carbohydrates, will assemble into new viral particles. 

The host cell's ribosomes will be hijacked to start mass production of viral proteins. As these accumulate, new viruses could assembly. This assembly can be divided into two processes: capsid assembly and genome packaging. Depending on viruses, these two processes can occur sequentially (for example with picornavirus) or simultaneously in a coupled manner (for example with adenovirus) . In the case of picornavirus, the capsids (ie, immature capsid or procapsid) are assembled first without the RNA genome. Subsequently, the RNA genome is packaged or inserted via a pore formed in the procapsid structure. By contrast, in the case of adenovirus, the capsid assembly is coupled with the DNA genome packaging. Does a virus know which proteins to assembly in a capsid and which piece of genomic information to package? Viral capsid proteins can specifically recognise certain packaging signals  to selectively package either RNA or DNA. Drugs  interfering with any of of the Viral Assembly steps or SARS-CoV2 could cure the world of the current pandemic. Are such drugs these being developed?