If you think that your life for the past two years has been significantly changed by a virus (cue: coronavirus), you’re not alone. In fact, it’s not a hyperbole to say that human history has been largely shaped by entities remaining elusive from our naked eyes—viruses being one of them.
In conjunction with Virus Appreciation Day, let’s take a look at a few interesting facts about viruses!
Examples of types of viruses. Image credit: https://www.genome.gov/genetics-glossary/Virus
Technically, virus is not a living thing
Surprise, surprise. It turns out that scientists haven’t settled on THE debate: is the virus even alive?
To be considered a living thing, an organism must be able to grow, reproduce, and generate energy on its own. Viruses can’t do all that, at least not on their own. They are often thought of as being in a gray area between living and nonliving: they cannot replicate on their own but can do so in truly living cells and can also affect the behavior of their hosts profoundly.
If you look closer at a virus, it is essentially a composition of its genetic materials called nucleic acids (DNA or RNA) enclosed in a protein coat that may also shelter viral proteins involved in infection:
https://www.scientificanimations.com, CC BY-SA 4.0 , via Wikimedia Commons
How can an entity as simple as this be called a living organism, then? After all, living things like ourselves pride on our own complicated and intricate body systems. Yet, a virus surprises all of us the moment it enters a truly living cell (called host)—it hijacks the host and ‘forces’ it to reproduce its own genetic materials.
Mindblown, huh?
We’re not entirely sure about the origin of virus
There is much debate among virologists about this question. Three main hypotheses have been articulated:
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The progressive hypothesis: viruses arose from genetic elements that gained the ability to exit one cell and enter another.
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The regressive hypothesis: viruses may be descendants of more complex bacteria that lost their genetic elements over time.
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The virus-first hypothesis: viruses may have existed before all other cells.
No matter which hypothesis you settle on, one thing is for sure: the origin of the virus remains an interesting mystery.
Not all viruses are small
If you’ve known a little bit of microbiology, you’re taught that viruses are very, very small—even smaller than bacteria. That’s not entirely true. As scientists understand more about viruses, they discovered giant viruses, sometimes referred to as girus. Mimivirus (what a cute name!) is the largest and most complex girus known. It’s so huge that it was mistakenly identified as an amoeba for eleven years, before it got its current name and was classified to where it truly belongs.
Image credit: Cell-like giant viruses found. Mitch Leslie (April 6, 2017) Science 356 (6333), 15-16. [doi: 10.1126/science.356.6333.15]
Don’t forget about HIV/AIDS
While viruses are truly fascinating entities, we shall not forget the havoc it has wreaked on human’s lives. While COVID-19 certainly has taken a huge toll on the world’s well-being and economy, we would like to turn your attention to another silent epidemic: HIV/AIDS.
Image credit: https://www.hiv.gov/hiv-basics/overview/about-hiv-and-aids/what-are-hiv-and-aids
The human immunodeficiency virus (HIV) targets the immune system and weakens people's defense against many infections and some types of cancer that people with healthy immune systems can fight off. As the virus destroys and impairs the function of immune cells, infected individuals gradually become immunodeficient. The most advanced stage of HIV infection is acquired immunodeficiency syndrome (AIDS), which can take many years to develop if not treated, depending on the individual.
At the end of 2020, there were an estimated 37.7 million people living with HIV. Thanks to medical advancement, HIV/AIDS is not as fatal as it was decades ago. With antiretroviral therapy (ART), HIV infection can be suppressed, thus allowing a person’s immune system to recover. While there’s currently no vaccine available that will prevent HIV infection, scientists are working hard to develop one. Let’s hope one day we will have vaccines for HIV infection.
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Cover image credit: Photo by CDC on Unsplash
