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When you get sick the culprit is normally going to come in the form of bacteria, fungi or virus. This deadly trio is the root causes of almost all ailments (bar injury).  Unlike bacteria and fungi which have positive forms that actually help your body most viruses cause disease. Viruses need living cells (human, animal or plant) to replicate and grow. That means they are forced to invade other things in order to survive.

What are Viruses?

Viruses are small infectious agents that can only replicate inside living organisms.

  • Small
    • An average viral agent is 1/100 the size of an average bacterial particle.
    • To put it into prospective they are so small that you can’t even see them with normal microscopes.
  • Shapes
    • From GSCE bio I remember them looking kind of like a retro video game character with wiry legs and what not.
    • But they actually come in lots of different shapes and sizes (some are pretty amazing and beautiful).
  • Two parts (most viruses are made out of two main parts)
    • Genetic material made from DNA and RNA (long molecules that carry genetic information).
    • Protein coat
      • This protects the genetic material
  • Dependent
    • They are dependent on other living organisms to reproduce as they have no cellular structure - this is why they are often referred to as being on the edge of life
    • Viruses need to use parts from the cells of hosts (people, animals and plants) in order to produce new products for themselves. Often when they infect host cells they burst the cell killing it in order to:
  • Spread
    • They spread much like bacteria and in many different ways. Here are some examples of viruses and how they pass on from one person or animal to the next
      • Blood
        • Malaria (via host mosquitoes)
        • HIV
      • Snot
        • Flu
      • Spit (a good old snog can do it)
        • Glandular fever
      • Poo (failing to wash hands properly)
        • Norovirus

How Viruses Work

Viruses have a fairly complex life cycle as they are forced to take over a host cell

  1. To start off they have to get into your body somehow
    • As you saw above this can come from you eating something that contains a virus, getting a bug bite or breathing in a virus from somewhere
  2. Once in your body the virus will attach itself to a receptor one of your cells
    • As the receptors are pretty specific, viruses often attack a specific type of cell in your body
  3. Once it has attached itself to cell it will penetrate the member in order to get access to the cell
  4. It then goes through a process of “uncoating” in which it releases its genetic material into the cell
  5. The virus then uses building blocks from the cell to replicate its genetic material in the replication stage
  6. Finally in the release stage the virus makes a break for it. It will either burst the cell to escape and infect another cell or it may turn malignant (make the cell reproduce out of control)


Symptoms of viruses can vary on what type of virus is affecting the body. Obviously you’re not going to be feeling too well, but some general symptoms to looks out for are:

  • Flu-like symptoms, runny nose, headache, fever, sore throat.
  • Feeling generally ill, run down and irritable.
  • Unexplained weight loss
  • Swollen tonsils

Treatment and Prevention

Your body is pretty bad ass and it can fight off a lot of viruses by itself. In fact in most cases it is forced to. There are no “cures” for viruses, though there has been an increase the production of anti-viral medications such as malaria pills. Viruses are just really hard to treat as they are so small and they hang out inside your cells. The most effective defense against viruses are vaccines:

  • Vaccines work by giving you a very weak strain of the virus, one that your body can fight off without you even noticing
  • It gives your body the practice for when the real virus comes along and leaves behind specific  antibodies in your blood ready to react at the first sign of a new attack

Antibiotics are not effective against viruses. They are developed to fight bacterial infections and they don’t work against these guys.

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