Addiction has strong links with an ancient retroviral infection, according to a new study that says its genetic traces in the human genome may influence certain addictive behaviors displayed by some people today.
The study was published in Proceedings of the National Academy of Sciences on Monday, and the thinking is that our ancestors were infected with retroviruses on a regular basis, National Geographic noted, with traces of one virus has been carried through our DNA for millions of years
Scientists believe the strain – HERV-K HML-2 (HK2) – may still be present in modern humans and that a variant of it close to the gene RASGRF2, which is involved in the brain’s production of the feel-good chemical dopamine, occurs more frequently in drug addicts.
Researchers from the Oxford University and University of Athens set out to establish how HK2 manipulated nearby genes and what role that may play in addictive behaviors.
By analyzing samples of Hepatitis C Virus (HCV)-infected patients from the U.K. and patients from Greece who had been infected with HIV by injecting drugs, researchers found that people addicted to drugs were two to three times more likely to have the integration of HK2 within RASGRF2.
“Our study shows for the first time that rare variants of HK2 can affect a complex human trait,” said Professor Aris Katzourakis from Oxford University, who co-directed the study.
“Most people think these ancient viruses are harmless,” added Dr. Gkikas Magiorkinis, from the University of Athens, who led the study. “From time to time, people have shown overexpression of HK2 in cancer, but it has been difficult to distinguish cause from effect.”
Researchers said the study’s findings could help medicinal targets be developed for drug development.