Humans Naturally Produce Proteins
Which Prevent H1N1 and other Viruses
Howard Hughes Medical Institute researchers have identified a naturally
occurring human protein that helps prevent infection by H1N1 influenza
and other viruses, including West Nile and dengue virus.
A research team led by Howard Hughes Medical Institute investigator
Stephen J. Elledge and his colleague, Abraham Brass, discovered
that human cells respond to infection by the H1N1 influenza virus
by ramping up production of proteins that have unexpectedly powerful
antiviral effects. In cultured human cells, those proteins, whose
functions were previously unknown, block the replication of H1N1
influenza virus, West Nile virus, and dengue virus.
The finding, reported December 17, 2009, in an early online article
in the journal Cell, is the result of a collaborative effort by
researchers at the Howard Hughes Medical Institute, Harvard Medical
School, Massachusetts General Hospital, Yale Medical School, and
the Wellcome Trust Sanger Institute in Cambridge, UK.
As with other viruses, the influenza virus has only a few genes
of its own, and must commandeer proteins produced by its host
cell to complete its life cycle. The current study began when
Elledge and his colleagues set out to identify the host proteins
that the H1N1 virus needs to enter cells and replicate inside
them.
To sift quickly through thousands of proteins, Elledge and his
colleagues set up large arrays of cultured human cells, and then
used a robotic device to deliver small strands of interfering
RNA (siRNA) to each well in the array. Each siRNA strand was designed
to block the expression of an individual gene, and thus the production
of the corresponding protein. For each such gene/protein "knockdown,"
the automated devices recorded the effect on H1N1 activity by
measuring any change in the presence of viral protein on the surface
on infected cells.
"This work illustrates the important interplay between the
cell innate immune response and virus replication," said
Lamb. "If influenza didn't induce an innate immune response,
influenza would win the war and then the cell (organism) would
die."
Interestingly enough, vaccines promote the inhibition of the immune
response which may temporarily leave cells vulnerable to attack.
Reference Sources 128
December 18, 2009
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