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article imageMore ancient viruses in human DNA discovered

By Tim Sandle     Apr 1, 2016 in Science
It has been known for some time that our DNA contains genetic material that was once viral. New research suggests the extent of this is greater than previously realized.
In new research, 19 new fragments of non-human DNA have been discovered. The origin of this genetic material is from viruses that first infected our ancestors hundreds of thousands of years ago.
The distribution of the ancient viral DNA is not evenly distributed through the human population. An examination of 2,500 people found 50 carried on a particular — and special — fragment of viral DNA. This fragment contains a full genetic recipe for an entire virus. It is not known if this material could ever result in the virus replicating. The virus was found using methods for characterizing repetitive DNA sequences.
The research considered the entire span of DNA, or genome, from selected people living in different regions around the world. Each person’s genome was compared to a “reference" human genome.
The types of viruses detected are called human endogenous retroviruses (HERVs.) These ancient infectious viruses once inserted a DNA-based copy of their own RNA genetic material into our ancestors' genomes. The new, large ancient virus belongs to a family called HERV-K, and the new virus has been coded Xq21. It represents the second intact virus found in a human.
Over subsequent generations the virus-generated DNA was copied. Some of the viral material serves no apparent purpose; other material plays a role in human health. For example, according to Bioscience Technology, one viruses appears to assist in helping a pregnant woman's body construct a cell layer around a developing fetus to protect it from toxins in the mother's blood.
It could, based on current estimates that about 8 percent of "human" DNA derived from viruses. Lead researcher, Dr. John Coffin notes in a research brief: “This research provides important information necessary for understanding how retroviruses and humans have evolved together in relatively recent times."
The project was a collaboration between Tufts University and the University of Michigan Medical School. The new research is published in the Proceedings of the National Academy of Sciences. The research is titled “Discovery of unfixed endogenous retrovirus insertions in diverse human populations.”
More about ancient viruses, Dna, Human dna, Virus, Viruses
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