Metal Gear Solid - FOXDIE

Ah, the Metal Gear Solid games. A legendary series of stealth games with more social commentary than your average newspaper. The first Metal Gear Solid game was released in 1998 on the Playstation, and the most recent instalment in the series, Metal Gear Solid 4, was release on the Playstation 3 in 2007. With another two games on the horizon (Ground Zeroes, and the unconfirmed-but almost-guaranteed-to-happen Metal Gear Solid 5) it doesn't seem like we will be seeing the last of Solid Snake any time soon.

The Set-Up
In the original Metal Gear Solid, you play as Solid Snake, a soldier who is brought out of retirement in order to neutralise a group of terrorists (as so often happens with these things). Whilst on your mission fighting shamans, psychics and ninjas, you find that several people mysteriously die of heart attacks when in the presence of Snake. It is later revealed that Snake is infected with FOXDIE, an engineered retrovirus that has been designed to only target and kill specific individuals.


The Science
You may have heard of retroviruses before, since one of the most infamous viruses in the world  is one. HIV, along with other retroviruses, makes use of a cell's on DNA in order to replicate itself, which damages the body in the process. A retrovirus will invade a cell and use an enzyme called integrase to incorporate its own viral DNA into the host cells DNA.

At this point, the host cell doesn't think anything as wrong. It continues to produce the various proteins encoded into its DNA. Only now, the cell also contains the viral DNA from the retrovirus, which means it also produces a bunch of viral proteins it didn't before. Hands up if you can guess what these viral proteins now make up!

If you said "new retroviruses", A+ for you. These viral proteins form up into new retroviruses, which can now spread out into the body and infect more cells. As the newly formed retroviruses leave, they kill the host cell by bursting out through the membrane, not entirely unlike the chestbursters from Alien. But that's beside the point.

In Metal Gear Solid, FOXDIE works a little differently to a normal retrovirus. It follows all the same steps a real world retrovirus, right up to the point where it has been combined into the host cell DNA. Rather than producing the proteins needed to create new viruses, the FOXDIE DNA triggers the production of tumour necrosis factor epsilon. These tumour necrosis factors, or TNF, travels through the blood stream to the heart, binds to the receptors there, and causes the myocardial cells to die. This riggers a heart attack, and the unfortunate individuals dies.

Whilst this sounds like science fiction, tumour necrosis factor is actually a real thing, and despite having a downright terrifying name, is actually a good thing. TNF alpha is vitally important in regulating the division of cells in our bodies. If a cell divides unregulated, it can lead to the formation of a cancerous tumour. If this happens, certain processes are in place that trigger the production of TNF. When TNF binds to a cell it triggers the cells' self destruction, preventing it from become a tumourous growth.

Whilst FOXDIE's tumour necrosis factor epsilon but not actually exist, the scientific theory behind it is. Retroviruses do invade cells, hi-jack the DNA and produce new prtoteins. Tumour necrosis factor can trigger cells to self destruct. Fortunately, no-one in the real world would ever think of weaponising something like this, right?

Right?