Friday, March 7, 2014

This Week's Sci-Light!




A National Geographic article, The Lurker: How a Virus Hid in our Genome for Six Million Years, discusses Dr. David Markovitz's work at the University of Michigan investigating the blood of people infected with HIV (human immunodeficiency virus) that weakens the host's immune system making the host susceptible to other pathogens. By investigating what other viruses could have attacked the host, Markovitz and colleagues found a virus that seems to have originated in a common ancestor of chimps and humans!

First, let's review a little background, and then move on to the discovery.  HIV is a type of retrovirus. A retrovirus is a virus that integrates it’s RNA genetic code into the host genome after being reverse transcribed into DNA - amazing! Within the human genome, researchers have identified 100,000 sequences of retrovirus DNA across over fifteen chromosomes. These sequences comprise nearly 8% of the human genome. 

Dr. Markovitz and his colleagues analyzed the DNA of HIV patients and found an endogenous retrovirus called HERV-K in a form previously undiscovered.  They wondered if this virus could have been lurking in the human genome and checked the human genome sequence, which is about 95% compiled.  With no luck, they turned to the completed chimpanzee genome and found once copy of HERV-K which they named K111.

The researchers came back to the human genome and discovered K111 was indeed hidden there!  The data suggests that "the virus infected our ancestors not long before the split between humans and chimpanzees roughly six million years ago."

To follow the details of their discovery and its implications, check out the article.  This story calls me to remember there's so much to learn and understand and calls us all to be Sci-Curious!

Written by Jacob Steenwyk
Edited by Cynthia Joseph

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