Study shows why winter is 'flu season'

[Guest guest]

Study shows why winter is 'flu season'

 

Reuters

1:38 PM EST March 3, 2008

 

Influenza viruses coat themselves in fatty material that hardens and

protects them in colder temperatures - a finding that could explain

why winter is the flu season, U.S. researchers reported on Sunday.

This butter-like coating melts in the respiratory tract, allowing the

virus to infect cells, the team at the National Institutes of Health

found.

 

" Like an M & M in your mouth, the protective covering melts when it

enters

the respiratory tract, " said Joshua Zimmerberg of the National

Institute

of Child Health and Human Development (NICHD), who led the study.

 

The NICHD is one of the National Institutes of Health.

 

" It's only in this liquid phase that the virus is capable of

entering a

cell to infect it. "

Experts have long pondered why flu and other respiratory viruses

spread

more in winter. No one explanation, such as people staying indoors

more,

or the destructive effect of the sun's radiation in summer, has fully

explained it.

 

The new report, published in the journal Nature Chemical Biology,

could

lead to new ways to prevent and treat flu, said NICHD Director Duane

Alexander.

 

" The study results open new avenues of research for thwarting winter

flu

outbreaks, " Alexander said in a statement.

" Now that we understand how the flu virus protects itself so that it

can

spread from person to person, we can work on ways to interfere with

that

protective mechanism. "

Zimmerman's team used a type of imaging called nuclear magnetic

resonance imaging to look at the outer coat of flu viruses.

 

Going out into the world

 

Viruses cannot replicate on their own but instead must hijack a

living

cell. Influenza viruses have a membrane-like outer coating that they

fuse to the victim cell.

They inject genetic material into the cell, turning it into a virus

factory. Some types of viruses simply explode out of these hijacked

cells, but influenza instead " buds " out, and uses lipids such as

cholesterol from the cells to make a membrane to help it do so.

 

CONTINUED

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