July 14, 2009

Swine Flu Research Unlocks More Clues In Global Pandemic

The swine flu virus results in more lung damage than regular flu strains but still reacts positively to antiviral drugs, says a study on lab animals announced on Monday.

Virologists headed by Yoshihiro Kawaoka from the University of Wisconsin took H1N1, removed from patients in the US, and several other seasonal flu viruses and injected them in mice, ferrets, macaque monkeys and miniature pigs.

They discovered that H1N1 resulted in more serious lung lesions in mice, ferrets and macaques than the regular flu virus.

However, it did not affect the mini-pigs, which might pinpoint the reason why there is no evidence that pigs in Mexico became ill with the disease prior to the human outbreak.

The team discovered that the virus was very responsive to two approved and two experimental antivirus medications, including Tamiflu, now being quickly sent around the world.

This reinforces the drugs' role as a "first line of defense" in the pandemic proclaimed by the UN's World Health Organization (WHO).

The letter, available online in the British journal Nature, noted that the current swine flu seems to be connected to the 1918 strain that killed tens of millions of people.

The proof comes from blood samples taken from people born prior to 1920. Their blood had antibodies that recognized the new strain and reacted to it. However, similarities between the two viruses do not mean they are equal in virulence.

Actually, the current strain is mild when measured against the viruses that attacked several times in the last century.

Scientists from the Massachusetts Institute of Technology (MIT) and the US Centers for Disease Control (CDC) feel that the answer is in the virus's faulty ability to find to a home base on cells in the respiratory tract.

To find one, it must undergo mutation in surface proteins, they wrote in a paper available in the US journal Science.

94,512 confirmed cases of swine flu have been accounted for, including 429 deaths, says the WHO's website on Monday.

The concern over the present strain of H1N1 is that it could collect genes from other strains that would allow it to become highly dangerous and contagious.

"Sustained person-to-person transmission might result in the emergence of more pathogenic variants, as observed in the 1918 pandemic virus," it says.

A different worry is that H1N1 could collect mutations allowing it be defiant to Tamiflu.

"Collectively, our findings are a reminder that (strains of swine flu) have not yet garnered a place in history, but may still do so."


On the Net: