Retroviruses reinfect humans
Genomic sequences are remnants of repeated reinfections during primate
evolution
By Cathy Holding

There are 98,000 human endogenous retroviral (HERV) sequences in the human
genome, most inactivated by mutations. A new study in the March 22 PNAS
reveals that this large number of insertions is most likely the result of
germline reinfection rather than retrotransposition or complementation.

"What we think is really happening is that in the past 30 million years,
there have been very many of these elements, not fixed but just present in a
small number of individuals," said Robert Belshaw, from the Department of
Biological Sciences, Imperial College London, and lead author of the study.

These would have been infecting and moving about, possibly between
individuals, but certainly within individuals, from somatic cells back into
germline cells. Periodically, one would pick up a mutation that would stop
it from moving about. "Once dead, there would be no selection against it
from the host. They're just a bit of junk, and they could then drift to
fixation by chance," Belshaw told The Scientist.

"The idea which some people had held was that a lot of these elements,
although they come originally from viruses, had actually spread around the
genome by mechanisms other than virological ones," said John M. Coffin,
professor of molecular biology and microbiology at Tufts University's
Sackler School of Graduate Biomedical Sciences

Read the rest at The Scientist.com
http://www.biomedcentral.com/news/20040323/01

Posted by
Robert Karl Stonjek.
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