This year's cold and flu season is in full swing around the country and unsurprisingly, many people are finding themselves sick with viral infections. I myself ended up bedridden for about a week with some sort of throat/chest/head infection. Once everything cleared up and I was watching my daughter for signs of infection, I began to wonder, how did we all get sick in the first place? What happened when the virus entered my body? How did I fend it off? I figured there was no better time to learn about viruses than in the middle of an outbreak, so let's get started!
Photo Credit: MediMoon.com
A virus, by definition, is a microscopic organism consisting of a nucleic acid (DNA or RNA) shrouded in a coat of protein. It is about a thousand times smaller than a bacteria which is already much smaller than the average human cell. Viruses cannot be seen by a standard light microscope. In order to observe them, you would need a scanning electron microscope and the pictures taken of them are quite remarkable. The shapes they have undertaken are extraordinary, ranging from robotic looking drones to spherical globs lined with several appendages.
There is some debate as to whether they can even be considered living organisms. While they do carry the DNA and RNA necessary for reproduction, they do not possess the enzymes needed for the chemical processes to take place. In order to reproduce, they need a host. That is where we come in.
Because viruses are so small, they are able to "hitch a ride" on particles of air or water vapor. For example, if someone who is carrying the cold or flu virus coughs or sneezes, the virus can ride the air right into your nose or mouth. This is where the excitement begins! Once inside your respiratory system, the cold virus will seek out a host cell. When it finds one, it will either dissolve right through its membrane, or it will lock on to the outer membrane and inject its genetic material directly into the cell. Once the genetic instructions are inside the host cell, the host will stop all of its normal activities and direct all of its chemical functions to replicating parts of the virus. The host cell, much like the virus itself, has become a robotic drone, devoted solely to the reproduction of the virus!
|The respiratory system is under a full Virus Attack!|
Once the host cell finishes building virus parts, it devotes its energy to assembling the virus copies. Viruses are copied and put together, over and over again, filling the cell with viruses. Finally, the cell begins to grow in size, expanding until it EXPLODES as thousands of viruses break free and begin to search for new host cells to infect. The virus outbreak is in full swing and the human respiratory system is under attack! Viruses attack cells in the nose and from there they can drip down to the throat where the resulting infection can cause you to have a sore throat. The viruses can be inhaled into the lungs causing an infection in the chest, and can even reach your muscles, causing the familiar aches and pains that a bad cold or flu can bring.
As the virus attack reaches its peak, thousands of healthy respiratory cells are taken hostage to do the virus' reproductive dirty work. The casualties run high as the healthy cells are killed off in the explosive release of millions of new virus drones. With so much action going on in the body, it isn't long before the immune system begins to take notice. The first response of the immune system is to raise the temperature of its environment. We experience this as a fever and it serves an important purpose. The chemical processes that occur in our cells need a consistent temperature of around 98° F in order to properly function. If the temperature increases by just 1 or 2 degrees, the rates of cellular and viral reproduction will be slowed dramatically.
|Yellow = Macrophages Dark Blue = T-Cells Green = B-Cells|
Yellow/Green = K-Cells Light Blue = Cytoplasmic T-Cells
Red Flags = Antibodies
As the immune system begins to react, all sorts of different things begin to happen! Macrophages are alerted by the presence of foreign organisms. They swallow the viruses, leaving small pieces as flags to be identified by the rest of the immune system. T-Cells take note and send a chemical call to arms to the rest of the white blood cell brigade! B-Cells swarm the macrophages, identifying the components of the enemy virus. They make antibodies by the millions and send them out to tag the viruses for destruction! Once the viruses are tagged, killer K-Cells are able to identify them and swallow them whole, dissolving the viruses into tiny harmless particles.
The K-cells can't quite reach all of the viruses though. Some viruses break past the defenses and STILL infect host cells. This means that back-up viruses are still being produced by infected cells! This doesn't look so good for the human body. This is when the Cytoplasmic T-Cells come up and destroy the infected cell and all of the replicated viruses within. The death of these cells bears no consequence for us, there are trillions more that are healthy and ready to make our bodies work.
The tables have turned and the immune system is prevailing in protecting our bodies and our respiratory system! After an epic battle, the white blood cells have done their jobs of identifying, attacking, and destroying viruses and infected cells. Now our body has to remember the virus outbreak so they can protect against future attacks. Memory cells patrol the body, constantly on the lookout for infiltrators that match the given instructions and antibodies remain, ready to tag any stragglers for destruction. All is calm in the microbe war, for now. As for the viruses...
The viruses are still within the bodies of other human beings. When the host cells are copying the DNA or RNA for virus replications mistakes can be made. Nucleotides can be placed in the wrong slots of the helix. Changes can be made in the genetic ladder and when they do, evolution has occurred! When these new viruses enter the battle, there are no antibodies yet made for them. They are essentially given free rein in the respiratory system until the whole process starts all over again.
We as humans do, however, have a secret weapon in our virus battle and every year we get a new upgraded version! It's called the Flu Vaccine and it is able to trigger the production of antibodies and memory cells without having to undergo the epic and at times dangerous battle between our bodies and viruses like the flu! Scientists have been able to place just the components of new and old viruses into vaccinations so our immune system can recognize and remember the viruses. In this way, their reach and effectiveness is dramatically reduced and people can have up to a 70% chance of not even getting sick when the flu virus comes around! In fact, we've become so adept at creating these vaccinations that in some cases, you don't even need a shot to be vaccinated! Increasingly, nasal spray vaccines have become available so kids can get the benefit of the flu vaccine without the ouch of the shot!
This cold and flu season has had quite an impact on communities across the country, our family included. Yet, I've never had such an informative time being sick. Now that we have a much better understanding of how viral infections work, Kat and I have a much greater respect for our bodies and how they work to protect us. I now understand the epic battle occurring in my body when my throat hurts, I have a fever, and am generally "just feeling icky". So thanks body, immune system, and science, for helping to protect us as you stem the tide of the next... Virus Attack!
|Thanks immune system!|
Image Credit: HPlus Magazine