I haven’t posted in a few days because unfortunately I was taken down by a very nasty stomach virus. After several days of being out of commission, I am back from the dead and feeling much stronger. The critters fighting for supremacy in my gut were defeated in the end, but they fought valiantly enough to warrant a tribute post. So, in memory of the alien-like, pseudo-lifeforms that died in the war over my gastrointestinal tract, here are a few interesting things about viruses you may not have known.
This is linguistic, but there is a lot of confusion about what the plural of virus is in English. There is one cactus, and two cacti; a cell has one nucleus, but when it divides it splits into two nuclei; a mushroom is a fungus, but throw a handful into your shopping cart and you have a basket of fungi; so it follows that when a virus replicates in the lining of my stomach I am infected with millions of viri, right? Wrong! Actually this “-us” to “-i” rule is one of our favorite to over-apply, but when you think about it there are plenty of exceptions. For example, when you update your Facebook “status” more than once per day, they do not become your “stati”, and when you take a break you’re on a “hiatus” but if you take a second break they are not your “hiati”. And don’t even get me started on more than one octopus! The word “virus” comes from Latin meaning “venom”, but the way it was used didn’t really have a plural form at all. The word “viri” is the plural form of “man”, so calling one of the nastiest, most vicious human-killers “viri” is a little insulting to us males of the species. Although, given the historical actions of men, perhaps this fact makes you want to refer to the little bugs as “viri” anyway. I leave that up to you. Suffice it say that the linguistic experts have spent a lot of time examining the latin origin of “virus” and after much discussion about which declension the word is and whether we should use genitive singulars when working with a nominative, the experts have decisively ruled that the plural form of “virus” is “viruses”. Phew.
Living or dead?
One of the most fascinating aspects of viruses is the question of how to classify them. Are they nasty, toxic chemicals like arsenic or mercury or are they living, microscopic organisms like bacteria? As it turns out, they are somewhere in between these two. Biologists made a definition centuries ago to easily distinguish all the living things from the dead ones. Self-replication. So while your goldfish might be simple-minded and your computer can do advanced calculus in under a second, the goldfish is living and the computer is dead. The difference is that the goldfish can self-replicate; it can procreate to make a new goldfish that shares its attributes, whereas the computer has no such method of procreation. That was all well and good centuries ago, but the more we discover the world around us the more we have to question if that is the best definition of life. Viruses contain genetic material (some of them have DNA and some have RNA), and that genetic material contains all the instructions to make a new virus. But, the virus doesn’t have all of the necessary machinery to take those instructions and turn them into a new virus. That is why viruses have to infect a host (like my stomach lining) to reproduce. They have to get that genetic material into another organism to hijack their machinery to make new viruses. So that puts them in a strange category. They contain genes and work hard to get those genes copied and reproduced, but they can’t do it by themselves. So… viruses are not among the “living” nor are they fully “dead”, and they move with a single-minded purpose of infecting other living organisms to turn them into virus-making machines. They’re zombies!
Method of infection
By far my favorite quality of viruses is how they hijack cells to make baby viruses for them. Since they have their own DNA or RNA, they need to figure out a way to trick the host cell into turning those genetic instructions into proteins that can assemble into new viruses. To do that, many viruses literally insert their DNA into your cell’s chromosome. That’s right! It inserts its DNA into your DNA, so that your cell doesn’t know whose is whose. Your poor cell then does its job turning your genes into proteins and by accident starts making virus proteins as well. In fact, about 8% of your own DNA came from viruses. This happens when a virus successfully inserts DNA into your cell, but for one reason or another the viral DNA doesn’t get replicated enough to kill the cell. In these cases, every time the cell divides it copies its own DNA and the viral DNA as well. This can even get passed on to your children if those cells eventually become sperm or egg cells. Right now, you are walking around with hundreds of virus genes in your DNA. You are, then, part-human part-virus!
Zombie viruses stick their DNA into our chromosomes, mad scientists up the ante
On a final note, I’ll quickly mention how scientists responded to the discovery that viruses can stick their genes into our chromosomes: not with horror but with delight! Since Mendel originally discovered that living organisms have genes, scientists have been dying to figure out a way to change those genes artificially. Imagine the power! Children born with horrible genetic diseases like sickle cell anemia could be cured if we could just switch out the messed up gene with a correct one. And imagine the scientific studies we could conduct! What better way to understand the functions genes play than to have the ability of changing them as we wish? Although it sounds like a science fiction novel, thanks to viruses this is now happening. It’s called gene therapy. Scientists have figured out how to gut a virus, removing all of that nasty virus-making DNA, and replace it with whatever gene they want. They then simply inject the virus and let it do what it does best. It infects the cells, inserts its DNA into the genome, and presto! You have successfully changed the genetic makeup of the cell.
This is obviously a gold mine for science fiction writers everywhere, but don’t worry. The moment you yank out all of the virus DNA, you get rid of its ability to make new viruses. Therefore, these modified viruses that are getting injected are incapable of replicating or spreading.
… in theory.
*music of doom*