Humans on Viruses: Affecting Evolution Since the First Vaccination

Every year doctors and researchers tell us to remain vigilant on vaccinating ourselves and those around us. They always seem to be reminding us that the vaccine that we may have received last year may not be as effective for us this year, and that newer, more up-to-date version of the vaccines. Many wonder...why is it that our immune systems coupled with the power of such advanced vaccines are not enough to fight off a seemingly harmless microscopic organism? Why does it feel like viruses are constantly one step ahead of whatever vaccine that we have prepared for them? The answer is evolution. It affects all organisms around us, biotic or abiotic, on both the macroscopic and microscopic level, and just because we cannot see the change happening right before our eyes, does not mean that it isn't there.

One of the most famous examples of viral evolution is the Influenza A (H1N1) virus, better known as the "Swine Flu." Michael Deem, a bioengineer here at Rice University attributes the swine flu's ability to jump from pigs to human solely on evolution from both humans and the virus. Scientists explain that the reason that the viruses are able to evolve and "attack" other species so quickly comes from the fact that they have multiple strands of RNA that can mix and swap to create many different combinations leaving room for many types of the flu virus with different strengths and weaknesses and leaving much room for mutations. Human bodies are usually very vigilant about building some sort of resistance to most viruses throughout generations. However, viruses are also very vigilant on adapting and even sometimes accidentally mutating in order to increase their chance of fitness and survival throughout their generations. Peter Dasak of the wildlife trust also states that the ability of the virus to spread and replicate so quickly comes from their ability to take advantage of human contact.

Another example of a continuously evolving virus is the human flu virus. The vaccine for this virus is constantly changing because the rate at which the virus reproduces is incredibly fast. With so many chances for the virus to reproduce, it makes it gives the viruses more chances to create more diverse offspring and more chances for the offspring to contain mutations that have a resistance against the vaccines and our own natural immune systems. As the human body continues to adapt and grow resistance to certain strains of the human flu, the human influenza virus is also finding its own ways to survive. It almost seems as though the influenza virus is evolving along side with the human immune system, which is why it seems as though humans are having a huge impact on the way the viruses evolve.

The biggest contributors to viral evolution are the vaccines themselves. Researchers have come up with what seems like a vaccine for every virus that they know will infect human bodies. Vaccines work by injected a small amount of a seemingly harmless strain of whatever virus researchers feel will be the most prevalent that season against humans that way the human immune system can begin to secrete the antibodies necessary to combat the virus when you come in actual contact with it. However, because of the high rate of replication and mutation in viruses, usually by the next year, viruses have found a way to combat the vaccine for the strain in the previous year, or have an entirely new strain altogether. With that being said, it seems as though the vaccinations we receive have the biggest affect on viral evolution to date.

Although it may not seem so, every action we take might be another step towards building our immune system to help combat another strain of virus, which in turn causes the virus itself to evolve as well. There is no “solution” to viral evolution, because to stop viral evolution would most likely mean the stop viral reproduction completely. Whether it be the glass of orange juice you drank to help bolster your immune system a little, or the vaccination that you receive at the doctor’s office to help you immune system a lot, humans have been a direct source of evolution for many viruses and will continue to evolve alongside these viruses for many more years to come.

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References:

Britt, Robert R. "Swine Flu Is Evolution in Action." LiveScience.com. Live Science, 28 Apr. 2009. Web. Feb. 2013.

MacLachlan, Allison. "Everyday Evolution Revealed in Flu Shots." LiveScience.com. Live Science, 06 Oct. 2011. Web. Feb. 2013. <http://www.livescience.com/16433-everyday-evolution-flu-shots.html>.
 
Zimmer, Carl. "10 Genes, Furiously Evolving." The New York Times. The New York Times, 4 May 2009. Web. Feb. 2012. <http://www.nytimes.com/2009/05/05/health/05virus.html?pagewanted=all>.

Image from: Bioquell