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Sci Tech
Hidden piece of influenza virus protein found
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The protein may kill immune system cells that fight the virus, thereby contributing to the virus's potency.
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FOR NEARLY 20 years, scientists have laboured under the assumption that the influenza virus comprises only 10 protein molecules that form its structure and carry out its activities. However, in Nature Medicine researchers report finding a new, ``hidden'' influenza virus protein.
This protein may kill immune system cells that fight the virus, thereby contributing to the virus's potency, the researchers say.
``We believe this is a groundbreaking finding, we're not yet sure how deep the ground is,'' says Jonathan Yewdell, a viral immunologist who led a team of scientists at the National Institute of Allergy and Infectious Diseases (NIAID).
``This might be the 'grand canyon' of the flu, in terms of understanding this virus's virulence, or perhaps only a narrow side ravine.''
The scientists turned up this new protein by accident, while sifting through bits and pieces of ``junk''peptides.
Junk peptides are short protein molecules the virus creates once it infects a cell and begins replicating.
They form when the process that translates viral genes into proteins goes awry, Yewdell explains. In other words, junk peptides result from genetic mistakes.
The immune system cells of mice, in fact, did recognise one of the peptides.
When the scientists examined the gene encoding this peptide more closely, they noticed it was suspiciously long for mere junk.
Wondering if this molecule might be a bona fide protein, Dr. Yewdell's team decided to see how much of it was created in cells infected with the flu virus. If it were junk, there should be only random copies of the peptide.
If it were a protein, large quantities of the molecule should be present. Dr. Yewdell used a technique called immunofluorescence, which makes the molecule glow green, to show how much of it infected cells contained. ``The cells we looked at just lit up.
Researchers saw large amounts of this molecule in the mitochondria of flu infected cells, and we knew it was a real protein.
It turns out that this protein is created when ribosomes, the cellular machines that translate genes into proteins, begin reading the influenza gene called PB-1 in what was previously believed to be the wrong location.
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