New data show how bird flu quickly spreads

Aug. 18, 2006 at 3:45 PM

PITTSBURGH, Aug. 18 (UPI) -- New data indicate that the H5N1 virus that causes bird flu has been quicky spreading and evolving through a process called recombination.

Recombination occurs when viruses pick up new gene sequences to rapidly prolierate, and experts say both the bird flu and seasonal flu viruses have becoem quite adept at it.

The ability of viruses to achieve recombination makes it more difficult to develop vaccines to combat the bugs and also affects the timing and distribution of the vaccines, experts say.

Indonesian authorities recently released data that includes more than 400 human sequences that date back to July 2005, while Hong Kong University made public human sequences dating back to February of this year.

The Indonesian sequences revealed that all but one case outside of Karo have a novel cleavage site that does not match public poultry sequences. The human sequences from Indonesia also contain genetic sequences from both the Fujian and Qinghai H5N1 strains, which are experts say are "accelerating the evolution of the H5N1 viruses."

The sequences from Hong Kong are known as the Fujian strain, which has beeen blamed for recent outbreaks in China and which has now spread throughout Southeast Asia.

"The recently released sequences from Indonesia have significantly increased the influenza database available for analysis, which now provides some striking examples of H5N1's recombination-driven evolution," said Henry Niman, presdient of Recombinomics, a company that is analyzing the genetic changes to the H5N1 virus.

"The newly released sequences demonstrate the utility of a robust sequence database for tracing the origins of influenza and selecting new vaccine targets for current vaccine production against future and emerging strains," he said. The company will present its analysis Aug. 21 at the Targeted Immunotherapeutics & Vaccine Summit in Cambridge, Massachusetts.

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