Why do flu spread in winter

Influenza viruses reinforce and protect themselves with a fat shell in cold weather - this finding helps explain why winter is often more susceptible to flu. The team at the National Institutes of Health found that shells like butter melted in the respiratory tract and allowed the virus to enter cells.

Joshua Zimmerberg, of the Institute for Child Health and Human Development (NICHD), who led the study, said: 'Similar to a chocolate M & M candy, this protective coating melts when they go. into the respiratory tract. Only during the liquefaction period can the virus enter a cell and make it infected. '

NICHD is part of the National Institutes of Health.

Experts have long explored why the flu and other respiratory viruses spread faster in the winter. There is no explanation, for example, that people are more indoors, or the destructive effect of solar radiation in the summer, can fully explain this.

The new report, published in the journal Nature Chemical Biology , could lead to new measures to help prevent and cure flu, according to NICHD Director Duane Alexander.

People walking on New York street in winter.New scientific work has discovered the reason why flu spreads strongly in the winter.(Photo: Keith Bedford / Reuters)

'The work opens new research directions against flu outbreaks in the winter. Now we can understand how the flu virus protects itself and spreads from person to person, so we can find ways to intervene in that defense mechanism. '

Zimmerman's team used nuclear magnetic resonance imaging to observe the outer envelope of the flu virus.

The way spread

Viruses cannot reproduce themselves but must attack a living cell. Influenza virus has a membrane-like shell that attaches to the victim cell.

They transfer genetic material into cells, turning into a virus factory. Some viruses only burst out of the attacked cell but the flu virus swells out of the cell and uses fluids like cholesterol from the cell to create a membrane that helps them escape.

Zimmerman said: 'This is the type of protein we are working on in the vaccine against.' The outer layer of protein, called hemagglutinin, gives the letter ' H ' in the name of the flu virus. Inside a warm cell, hemagglutinin is in liquid form. But at colder temperatures, they begin a process similar to crystallization, called degree of chemistry.

Zimmerman said: 'It solidifies gradually from 40 ^° C to 4 ^° C. I think this slow process causes flu viruses to survive at all temperatures. ' At warm outdoor temperatures, the protective layer melts and unless it is inside a living body of animals and humans, the virus will die.

The results of the study may help scientists come up with new ways to eradicate the flu. At low temperatures, a hard fat shell can resist some detergents, making it more difficult to remove them from their hands or other surfaces.

Flu viruses and other respiratory viruses spread through fluids through coughing, sneezing and talking. They can also stay on many surfaces and cling to fingers.