The flu virus turns cunning to outsmart the immune system

By Lorraine Fraser in London
September 23 2002
 

The influenza virus has developed a "nasty trick" - the ability to circumvent the human body's main defence against the disease, raising the prospect of a deadly global outbreak.

Scientists investigating 1997's Hong Kong flu have discovered it learnt how to bypass the immune system, and new flus have since been found with similar abilities.

"This is a really nasty trick that this virus has learnt: to bypass all the innate mechanisms that cells have for shutting down the virus," said Robert Webster, who led the study at St Jude Children's Research Hospital in Memphis, Tennessee. "It is the first time this mechanism has shown up and we wonder if it was not a similar mechanism that made the 1918 influenza virus so enormously pathogenic."

The 1918 virus killed 50 million people. Dr Klaus Stohr, the leader of the World Health Organisation's global flu program, called the 1997 outbreak "the last warning from nature" that the world faces a pandemic similar to 1918.

The Hong Kong virus, which killed six people, did not transmit easily from person to person, but other flu viruses with similar anti-immune abilities have since been identified. Dr Stohr said: "Imagine if that [Hong Kong] virus obtained a little additional capacity to be freely transmitted in humans - a large proportion of the population of the world would presumably have died."