Reovirus is a virus, made up of the proteins coded by its 10 genes. Two of the proteins are used as coatings for the virus core, one protein filament is used to attach to cells and the rest make up the core. The core manufactures the mRNA that the cell must make into proteins so that new reovirus cores and particles can be put together.

Reovirus in its natural state is somewhat protected from the body by a protein coat.

• The coat of proteins cover tiny points that allow attachment to cells called the Sigma1 fiber.
• The Sigma1 fiber is what actually attaches to cells.
• It is also what Reovirus antibodies (if there are any around) will attach to and mark the virus for destruction.

The protein coat helps protect the reovirus from the immune system but at the same time, it makes it hard for the reovirus to attach to cells.

If the virus approaches a cancerous tumor, a protein protease from the tumor will dissolve the outer coating.

• The sigma1 filament is now fully exposed.
• Sigma1 acts as a drill to drill though the mucous commonly found around cancerous cells.
• It attempts to attach to the proper surface receptors of any cell that it happens to run into.

At this point, the virus is very exposed to any of the persons antibodies that may be around. If any antibodies attach to it, the virus particle will be destroyed by the immune system.

The process of entering a cell strips the virus of a second coat of protein and exposes the core.

• The mRNA manufacturing core of the reovirus is exposed.
• The core at this point begins producing mRNA that the infected cell is supposed to automatically convert to proteins that can be assembled into more reovirus.

The response of the cell and whether or not it actually converts the mRNA to proteins for the virus depends very much on the type of cell reovirus has entered (ie. immune cell, liver cell..) and the state of that cell (ie. is it at some stage of cell division, is it crawling..).

Additional Info: Importance of the sigma1 protein glycosidase... or Shiff website
Graphics Source: Virus World (use pull down menu)