The last twenty years have been marked by a veritable explosion in sequencing technology. The Human Genome Project and it’s completion in 2003 was the crowning jewel of this burgeoning genomics revolution . The amount of information to come from this relatively new branch of science is literally mind-boggling and only grows with each passing day.
Interesting observations have come out of this massive amount of genomic data relating to the non-coding DNA in our genome. Less than 2% of the over 3 billion nucleotides in our genome are responsible for coding all of the protein that makes up a human being. This leaves a large question as to what exactly that other 98% of our genome is up to. Large parts (roughly 50%) are known as “junk DNA” with no accepted role, although new research is beginning to shed light on the functions of this DNA. The remainder of our genome is composed of long and short repeated sequences, transposons, retrotransposons and the topic of today’s article: endogenous retroviruses.
These elements are not human, they are fully viral in origin. This means that our genome is not just ours alone, we carry the DNA of many viruses that infected our ancestors in every cell in our own bodies.
In a word, yes. In fact, at this point multiple viruses have been identified as playing a role in the progression of many different cancers. The very first of these cancer-causing viruses was discovered by Peyton Rous in 1911, making the field of tumor virology over one century old. While this initial discovery was a virus that causes tumors in chickens, many important human cancers have since been discovered to have a viral component. The first human tumor virus to be discovered was Epstein-Barr virus (EBV) in association with Burkitt’s lymphoma in 1965 (see featured image). Since then many more viruses have been found to be tumorigenic (tumor-causing) in humans and more may still be awaiting to be discovered.
How is it that these many different viruses are involved in so many different types of cancers? What about these viruses makes them tumorigenic?
Despite our ever-dwindling supply of effective antibiotics, there have been a growing number of drugs that are effective against viral diseases. Many of these new drugs are not the result of happy chance or serendipity, as was penicillin, but rather the result of a process known as rational drug design. Continue reading Triumphs in modern drug design→
Deep in forests around the world a strange fungus is lurking. It doesn’t grow on trees, or from the ground like so many other fungi that we are familiar with. Instead, this fungus infects an unfortunate insect, turning it into a mindless zombie and control of its body until the fungus matures, erupting from the dying insect.
Think this sounds like a plot line from the X-Files? It’s not.
For some unfortunate insects this actually happens; enter the Cordyceps fungus.
In line with the recent article “Are viruses alive?” I would like to further explore the general nature of viruses. One question that I was recently asked was “how does a virus move?”
Being that viruses are not technically alive in the sense that we know it they also cannot move in a self-directed manner. This is in stark comparison to some other microbes such as Schistosomacercariae, a parasitic worm, which is capable of burrowing through intact human skin and gaining access to the vascular system within 5 minutes (1).
Thankfully viruses cannot do this, much to our benefit. Because of how they are constructed, viruses cannot mechanically move in a self-directed manner and are subject to movement solely based upon environmental interactions. Essentially, they are not only hijackers who take over cellular processes for their own good, but environmental hitchhikers as well. Continue reading How do viruses move outside the cell?→
In a sense, viruses are molecular hijackers bent on subverting host defenses, taking over a host cell’s ability to control nucleic acid and protein processing functions, and making copies of themselves to go out and infect more cells.
Viruses don’t divide like cells, don’t generate their own energy, and are fully dependent on host cells and their proteins to replicate.
Don’t let this simplicity fool you though, viruses have very sophisticated means of taking over cells and turning them into factories for making even more viral copies. However, since viruses are not capable of accomplishing many of the major of functions of life on their own outside of the host cell it has been debated for many years whether viruses are actually “alive.” Continue reading Are Viruses Alive?→