Genetic Analysis of Swine Flu Virus Finds New Mixture of Diverse Parts: H1N1 May Be Amenable to Future Vaccine Development

Article excerpt

The H1N1 swine flu combines old viruses in a new mix.

A detailed genetic analysis, published online May 22 in Science, pinpoints the origins of each of the virus's components. Many have been circulating in human and swine populations for years, but the new H1N1 virus combines the bits and pieces in a way never before seen. The analysis suggests that current vaccines probably won't provide protection from the virus, but that it is susceptible to some antiviral drugs and will be amenable to new vaccine development.

A study of the Virus's neuraminidase protein (the Nin H1N1),published May 20 in Biology Direct, also shows that the virus is sensitive to some drugs but that parts of the protein important for vaccine development and antibody therapies are already changing.

Pigs are the likely origin of the virus, says Nancy Cox, chief of the influenza division at the Centers for Disease Control and Prevention in Atlanta and a coauthor of the paper in Science. But it is still unclear whether the virus jumped directly from pigs to humans or infected an intermediate host first.

CDC has sent candidate virus strains for vaccine development to several U.S. manufacturers, says Anne Schuchat, CDC's interim deputy director for the science and public health program. Though the number of new cases in the United States is falling, Schuchat says, the virus is still active in pockets of the country. "We don't want people to think we're out of the woods yet," she says. "It could come back in the fall in the worst way."

Genetic analysis of the H1N1 virus reveals that three of its genes, including the hemagglutinin gene (the H in H1N1), originally came from the 1918 Spanish influenza virus and have been present in pigs ever since. The genes have not changed much, probably because pigs do not live long enough to get reinfected with the same virus, Cox says. …