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Ancient Neanderthal Viruses Discovered in Modern Human DNA
Traces of ancient Neanderthal viruses were discovered in modern human DNA by Oxford University and Plymouth University researchers.

Studies conducted on ancient Neanderthals have caught the fancy of many researchers worldwide. Not only are such studies interesting, they also reveal many unknown facts about the evolution of mankind. In one such study, researchers from Oxford University and Plymouth University discovered traces of ancient Neanderthal viruses in modern human DNA, reveals a press release.

For the study, researchers examined genetic data from fossils of Neanderthals and another group of ancient human ancestors called Denisovans and compared their findings to DNA data of modern-day cancer patients. The comparison led to the discovery that ancient Neanderthal viruses originated in our common ancestors more than half a million years ago.

Approximately 8 percent of a person's DNA is made up of endogenous retroviruses (ERVs) which are DNA sequences constructed from viruses that are passed from generation to generation. These DNA sequences are also part of the 90 percent human DNAs whose functions are not yet known, commonly referred to as "junk" DNA.

"I wouldn't write it off as 'junk' just because we don't know what it does yet," said Dr Gkikas Magiorkinis, an MRC Fellow at Oxford University's Department of Zoology. "Under certain circumstances, two 'junk' viruses can combine to cause disease -- we've seen this many times in animals already. ERVs have been shown to cause cancer when activated by bacteria in mice with weakened immune systems."

The recent findings will help scientists further investigate possible links between ancient viruses and modern diseases including HIV and cancer. Researchers of this study plan on doing exactly that with these ancient viruses belonging to the HML2 family of viruses.

"How HIV patients respond to HML2 is related to how fast a patient will progress to AIDS, so there is clearly a connection there," said Dr Magiorkinis, co-author of the latest study. "HIV patients are also at much higher risk of developing cancer, for reasons that are poorly-understood. It is possible that some of the risk factors are genetic, and may be shared with HML2. They also become reactivated in cancer and HIV infection so might prove useful as a therapy target in the future."

The team now plan on investigating whether these viruses have any role to play in a person developing diseases like cancer. Researchers also want to find out if these viruses are still active in the body and will do so by combining evolutionary theory and population genetics with cutting-edge genetic sequencing technology.

"Using modern DNA sequencing of 300 patients, we should be able to see how widespread these viruses are in the modern population. We would expect viruses with no negative effects to have spread throughout most of the modern population, as there would be no evolutionary pressure against it," the researcher said. "If we find that these viruses are less common than expected, this may indicate that the viruses have been inactivated by chance or that they increase mortality, for example through increased cancer risk."

Dr Robert Belshaw, formerly of Oxford University and now a lecturer at Plymouth University, who led the research, noted that certain technology breakthroughs earlier this summer made this research possible. He is also hopeful that further technological advancements in 2014 will help them conduct future researches more easily and effectively.