A good analogy can be made using an enemy tank as the virus ( the cannon is the method of entry into the cell and the operator inside the tank is the DNA). In this analogy, an automobile factory is the “cell”. The car manufacturing machinery becomes the machinery to make new tanks. Thus a tank that invades a car factory can take over this machinery to make tanks instead of cars. In essence this is the way a tank could undergo “reproduction”. The immune system protects the body as does the local police, C.I.A and other law enforcement agency protects the city or society.
Figure 2 The analogy of enemy tanks is used to represent a virus infecting the body. In this analogy the effects of a single tank are shown while in reality many viruses would be infecting the cell or body at the same time. This tank contains the DNA molecule or cookbook of the virus.
The story goes as follows with analogous explanations of the actual virus infection placed in parentheses: One day a large enemy transport helicopter flying over Detroit drops an enemy tank in the field close to the Chrysler factory. (an air borne virus infects the body)
The tank goes to the factory and blows a hole in the wall and drives into the factory ( the virus gains entry into the cell) then the operator of the tank pops out and kills the manager of the factory to take control of the manufacturing processes. This new “Boss” takes over the factory and announces that “Now we make tanks – not cars!!!” The machinery is changed according to the new instructions which were in the tank (Viral DNA is inserted into the cellular DNA and then activated). After the machinery is reconfigured, tank parts are made at a rapid rate and the factory is at full speed 24 hours a day. This increases the need for raw materials available to the factory and starts to wear the employees to the point of exhaustion. (Cells that are infected with virus are “sick” and function differently than non -infected cells) Tank parts are assembled into tanks and they rapidly occupy all spare space in the factory causing the walls to bulge as they are stacked to the ceiling. (Virus particles contain different sub-units. These different parts are manufactured in different parts of the cell and then assembled later to make the virus.) The analogy holds true of tanks being manufactured piece by piece then assembled to make the finished product. The entire process must be completed in the factory without alerting the rest of “city” (or body in this analogy). Therefore, the different parts are kept in the factory prior to assembly. (In real life these viral sub-units can be seen under the microscope as “inclusion bodies”. For example: Inclusion bodies for Rabies called Niger Bodies (black inclusions) are found in the brain cells of infected animals. The test for rabies involves sending the head of the suspected animal for the examination for these viral inclusions. While the process of viral infection and multiplication is covert, there are signs of infection that can be identified by the immune system.) Meanwhile the security guards (sentry white blood cells that patrol the body called neutrophils) notice foreign writing on some scraps thrown out of the factory (antigens). Actually defective cannon barrels thrown out as trash. The C.I.A. is called in because of the strange activity at the factory and because of the sighting of an Enemy Helicopter in this area earlier in the week.
The C.I.A. arrives in a large multipurpose urban assault vehicle (Macrophage) capable of many functions of surveillance and investigation (a macrophage is a white blood cell attracted by excited neutrophils, cell damage and foreign antigens). The C.I.A. picks up this cannon barrel with the enemy language on it (foreign antigen). The cannon barrels are placed into the urban assault vehicle and transported back to headquarters (the lymph node) for analysis.
Figure 6 The urban assault vehicle is analogous to a macrophage. This white blood cell is attracted to areas of intense activity and will pick up foreign antigens to be transported to the lymph node for processing.
In the C.I.A. headquarters (lymph node), analysis of the cannon barrel.(antigen) is performed. At headquarters the cannon barrel is identified as a potential threat to the national security and an all out effort is launched to find a way to inactivate the cannon. It was discovered that a cork-like device (antibody) that fits into the barrel would render the barrel inoperable. This device would be placed on all roads and highways (in the blood stream) and would seek to plug the cannon barrel, causing no further function.
Mass production of this cork causes intense activity at the headquarters (the lymph node becomes stimulated resulting in swelling pain and inflammation ). An alarm of potential invasion spread across the country activating the national guard and all local security officers to prevent invasion of other factories with anti-aircraft weapons that knock helicopters delivering the tanks out of the sky. (fever, chills and activation of interferon which prevents virus infection. Antibody production and dissemination of antibody to all parts of the body via the blood stream is the primary defense against virus infection.) Meanwhile, at the factory things have deteriorated; The factory will hold no more tanks or raw materials. All labor is exhausted and working conditions are intolerable, so finally, the factory walls tumble releasing the newly created tanks.
Figure 8 The CIA headquarters has examined the tank barrels and created a plug or “cork” that will inactivate it. These “corks” are mass produced. This is analogous to the lymphnode producing antibodies in response to antigen.
These tanks scour the major Detroit area looking for automobile factories to invade in an effort to make more tanks. The suspicion of invasion is true and another alarm (fever) is spread through the country of the ravaged Chrysler factory. As the tanks emerge they are encountered by corks (antibodies) which plug their cannon barrels so when they try to blow a hole in another factory the whole tank is destroyed. A race to produce enough corks occurs as the number of tanks increases. The eventual outcome depends on how fast the tanks reproduce verses the ability of the CIA (immune system) to respond. Also, the number of initial virus particles in the body has a lot to do with how fast the tanks multiply and cause disease.
Figure 9 War Zone back at the factory. The walls have fallen and tanks are released to invade other factories. The “Corks” have arrived and are attempting to control the invasion. This is analogous to the first wave of infection being battled by the first antibodies.