Headline July 25, 2018/ " 'VIRUSES NEXT VERTIGO' "


ANCIENT VIRUSES in your DNA?............

BUT John M. Coffin, a virologist at Tufts University, suspects that there's less to these viral proteins than meets the eye. He speculates that in many cases, cancer cells make viral proteins only because they are switching on genes willy-nilly - both human and viral genes alike.

"Our starting position is that this is largely a chance event," Dr. Coffin said, we have domesticated our viruses. We make proteins from endogenous retroviruses to carry out functions we depend on.

Some endogenous retroviruses offer protection against other viruses, for example. And some viral proteins are important for reproduction.

Placentas make viral proteins, and scientists have found that some types, known as synctins, fuse together placental cells, a crucial step in fetal development.

Five years ago, the French biologist Odile Reidmann and her colleagues went on a search for more endogenous retroviruses in the human genome.

Dr. Heidmann, who works at Gutave Roussy, a cancer research institute in Paris, discovered a stretch of viral DNA that had gone overlooked. She and her colleagues named it Hemo.

Dr. Heodmann was surprised to find versions of Hemo in other species. Among primates, the gene that makes this protein has largely changed over the ages.

Its consistency across many species shows that the gene and its protein must have an important job to do : "It isn't simply a relic," Dr. Heidmann said. Mutations to Hemo must have been harmful even fatal to the unfortunate animals who had them.

The placenta produces Hemo, and so do cells in the early embryo itself. But so far the researchers have not been able to figure out and why.

" It's very, very old, so it has to be something," Dr. Heodmann said. It's possible that  Hemo protein are a message from fetus to mother, dampening the mother's immune system so that it doesn't attack the fetus.

But there are other possibilities, too.

The early embryo is a hotbed of activity for endogenous retroviruses, recent studies have shown.

To understand why embryonic cells make viral proteins, scientists have run experiment to see what happens when viral genes are silenced. These experiments suggest that the viral proteins help the embryo develop a variety of tissues.

Early on, cells in an embryo can turn into any tissue. As these stem cells divide, they can lose this  flexibility, committing to becoming one kind of cell or another. After that cells typically shut down their viral genes.

Viral proteins appear to help keep stem cells from losing this potential. And Gikkas Magiokinis of the University of Athens has speculated that this feature might have a sinister origin.

Viruses might exploited embryos to make more copies of themselves. By keeping their hosts as stem cells for longer, the viruses were able to invade more parts of the embryo's body.

"When the host grows, it will have copies in the retrovirus in most of its cells," Dr. Magiorkinis said.

This strategy may do more than create more viruses. Stem cells can produce eggs and sperm in embryos. *The viruses may be raising their odds of getting into the next generation*.

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