Viruses: The ultimate supervillains
While virology and epidemiology are the hottest scientific disciplines of 2020, there are few articles dedicated to plain language explanations. Have you ever wondered how a virus actually harms us? Or how it works to invade our cells? To answer these questions, it’s best to start with a definition.
So, what is a virus?
Technically, a virus is not even a living thing. It has no cells, no brain, heart, nerves, anything. It’s simply some genetic material surrounded by a protein coat (a real virologist would probably correct me or add in more stuff here but hey, they’re all busy). And by genetic material I mean DNA, but I also mean RNA.
Uhh RNA?
Yep RNA – it’s not a typo. It’s a single-stranded molecule very similar to DNA, which is double stranded. In mammals, our genetic information is stored as DNA, but our genes get transcribed into small RNA sequences when they get ‘activated’ – these are known as mRNA molecules.
These guys are the messengers (the ‘m’ in mRNA literally stands for messenger), sending instructions from the boss (DNA) to the workers. The “workers”, then produce proteins from the instructions. Our bodies’ workers only produce proteins when given mRNA to read from.
Ok so, viruses…
Some viruses store their genetic material as DNA, and some actually store their information as RNA – and this is really bloody clever. Once the virus has entered the cell, its job is done. Yep – that’s all it does. Well, kind of.
How does the virus actually get into our cells?
Well, the viral protein coat contains ‘spikes’ or small projections that can bind to specific receptors found on the surface of our cells. The thing is, the virus has hijacked our own machinery in order to gain entry – the receptors that it binds to are used in often very important bodily functions.
So, SARS-CoV-2 (the COVID-19 virus) uses a receptor that’s involved in regulating blood pressure (it’s called ACE-2). Once it binds with ACE-2, our cell membrane fuses with the virus, granting it access.
Once it’s in, it gets our body to do everything for it. RNA enters our cell, the RNA makes its way to our protein machinery (the workers). Our ribosomes read the RNA as if it’s our own and begin to manufacture all of the viral proteins. Our cells then package everything up into perfect new viruses and then ship them off to go and infect more cells, and our cells do this because they have no idea that it’s a virus they’re creating. It’s so dastardly that you’d almost expect this type of plan from a supervillain.
I know COVID is the most topical virus at the moment, but I’d like to give a special shout-out to HIV. The way this virus manages to evade our immune systems is the ultimate villain move. First and foremost, HIV has a ridiculously high rate of mutation, meaning when our bodies replicate the HIV genome, the virus purposefully removes any quality control measures that might have otherwise been implemented. So, if there are any mistakes made when replication occurs, it actually works in HIV’s favour.
How?
Well, because it means our immune systems can’t keep up with it. So if our T and B cells (from my previous article on vaccines) finally make a match specific to HIV and begin to multiply, in a few days or weeks’ time they will be irrelevant – because they are no longer specific to the current form of the virus. It’s a cat-and-mouse game that our immune system can never win. This is the same reason why we need a flu vaccine every year: because influenza’s rate of mutation is also high. Oh and the cells that HIV infects? It’s our T cells themselves, so the virus is also actively depleting our soldiers. Pretty ingenious so far right? Well we’re not done just yet, we have one more thing that tips it right over the edge.
The HIV virus hides inside our DNA.
Whenever the virus becomes ‘latent’ (i.e. not active), it takes refuge right inside our cells’ nuclei (where DNA lives) and sits tight right there in our own DNA. It’s crazy, right? The virus comes equipped with its own ‘genetic scissors’: it can make a snip in our DNA sequence, insert its own sequence, then seal it all back up as if nothing’s happened. And the body can’t detect that.
There’s no cure for HIV and there’s no vaccine. But people can live with the disease relatively symptom-free, and this is because they receive a cocktail of drugs that act to disrupt the virus’s unique life cycle within our cells.
So that’s an introduction to viruses I hope you found informative. I snuck a few good scientific terms in there that you can use with your family and friends. If you have any questions or comments, please feel free to hit me up in the box below.
