Genes are the blueprints of organisms. Your hair color, height, voice, and many other traits, all are determined by the genes. You inherited half of these genes from your mother and half from your father when you were conceived. However, every once in a while some genes that aren’t part of your family tree will sneak in.
When biological invaders like viruses and bacteria enter your body, your immune system works to chop them up. Occasionally, some of the invader’s DNA will be chopped up in such a way that it gets incorporated into one of your own cell’s DNA. If this cell is an egg or a sperm, then this foreign DNA can be passed on indefinitely. And though this may seem like a rare phenomenon, our own species owes approximately 8 percent of its DNA to viruses that gave our ancestors their DNA.
When this happens, the foreign DNA is often useless for the body, and ends up being a blueprint for nothing. Occasionally, though, this new DNA will provide a beneficial trait, giving the organism an advantage. And, in a recent study by Megan R. Edwards and colleagues, it seems that this phenomenon could be giving bats an advantage.
After analyzing the DNA of 15 bat species, Dr. Edwards and her team were able to determine that each bat had some of the genes of an ancient Ebola virus. Not only was the gene prevalent in all of the bat species, but it remained largely unchanged for over 18 million years. Useless or detrimental DNA is often weeded out or changed in a species over generations, but when DNA remains unchanged for quite a while this is a good indication that it may have an important use. For this reason, Dr. Edwards and her team believed that the gene was useful for the bats.
Why the gene was so important for the bats is currently unknown and a problem that Dr. Edwards’ lab is working on. But they can take a good guess based on what the gene does in the virus. To efficiently invade a host, a virus has to out-maneuver the body’s immune system. The Ebola virus does this by producing a protein that blocks the immune system from reacting to its presence. The instructions for making this protein are encoded in the same strand of DNA that is present in the bats. Perhaps this gene plays an important role in regulating the bat’s immune system, possibly by reducing inflammation caused by benign environmental factors.
While this exhaustive research was unable to uncover a reason for the gene, it doesn’t rule out the possibility that it’s being used. In many species genes taken from pathogens play an important role in their functioning that are not immediately obvious. Syncytin is the name of a protein that is vital to placental development in humans, but is made from a gene that was taken from from a virus millions of year ago. Viruses have no placenta and yet this gene could be used for developing one all the same. This just shows the versatility different genes can have in different organisms and why it’s important to keep studying the effects of foreign DNA.