Paleogenomics News
Traces of an ancient extinct virus have been found in human DNA
Scientists from the USA and the UK have found traces of the ancient HERV-T retrovirus in the DNA of some primates, including humans. Based on the remains found, the gene was restored, which helped to find out why this virus disappeared. The researchers' article (Blanco-Melo et al., Co-option of an endogenous retrovirus envelope for host defense in hominid ancestors) was published in the journal eLife, Gizmodo briefly tells about it (retelling the press release eLife Viral fossils reveal how our ancestors may have eliminated an ancient infection – VM).
Retroviruses are infectious agents that are able to embed their own DNA into the chromosomes of an infected cell. If they infect gonocytes that produce germ cells, then the virus genes can be transmitted to offspring. Such traces can be used to determine the evolutionary relationships between different animal species. So, if foreign DNA in one form or another is found in all representatives of great apes, it means that they had a common ancestor who was infected with the virus. Thus, it is possible to determine the approximate age of the infectious agent.
Scientists analyzed the genomes of bonobos (Pan paniscus), gibbons (Hylobates) and other primates to compare changes in the genetic sequence of the DNA site associated with HERV-T. Knowing the approximate rate of occurrence of mutations in various species, the researchers found out that the virus appeared about 30-40 million years ago.
Based on the remnants of viral DNA found in humans, experts reconstructed the protein. It was part of the capsid – the outer shell of the virus – and played the role of a kind of key providing access to the host cell. However, organisms used genes embedded in their chromosomes to create protein derivatives capable of attaching to virus receptors on the cell surface. These receptors serve as "locks" for the key molecule, but the altered protein blocks them, preventing HERV-T from penetrating inside. According to scientists, this led to the disappearance of the virus about 10 million years ago.
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13.04.2017