Magazine article Science News

HIV-Like Gene Lies Buried in Human DNA

Magazine article Science News

HIV-Like Gene Lies Buried in Human DNA

Article excerpt

Scientists exploring the evolution of viruses can't dig into the ground for fossils. Instead, virologists can look inward to the genetic code within their own cells for signs of ancient infections.

As much as 1 percent of human DNA consists of genetic fossils of viruses that once inserted their genes into the genomes of human ancestors. While studying one such viral remnant, investigators have found that a virus that infected primates many millions of years ago used a protein with an uncanny resemblance to one employed by the modern killer HIV.

This unexpected finding may force scientists to rewrite their histories of the AIDS virus and similar viruses because they had considered the HIV protein, named Rev, a recent viral innovation, says Bryan R. Cullen of the Howard Hughes Medical Institute at Duke University Medical Center in Durham, N.C. He and his colleagues report their analysis of the Rev-like protein in the Nov. 9 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES.

Unlike most viral remnants, rendered inactive by the ravages of time, the one studied by Cullen's group retains several genes that can still make proteins, though they can't produce an infectious virus. Scientists believe that 30 million years ago the virus, which they call human endogenous retrovirus K (HERV-K), first infected the germ cells--sperm or eggs--of Old World monkeys whose descendants include the human species.

By entering the germline, the virus forever established itself in every cell of those monkeys' offspring. Such infections probably occurred a few dozen times over the next 25 million years, given that people have more than 50 different copies of HERV-K in their genome, says Cullen. …

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