CDC Mixes H1N1, H5N1 Viruses in Tests.More Deadly Swine Flu?
Sunday, October 25, 2009
CDC Mixes H1N1, H5N1 Viruses in Tests.More Deadly Swine Flu?
Public-health officials said that the H1N1 swine flu virus hasn’t mutated to become more deadly since emerging last spring. But what are the chances it will?
To find out, scientists at the CDC recently launched experiments in the agency’s labs in which they infected ferrets with both the new H1N1 virus and the highly lethal H5N1 avian flu virus to see if they might “reassort” to create a new hybrid.
The scientists want to know whether a combination of the H1N1 virus -– highly transmissible, but not terribly deadly -– and the H5N1 flu virus could create an easily transmissible, deadly scourge.
The two viruses could mix if they infected the same person simultaneously. While the experiments could produce viable combinations of the two viruses, the real question is whether any could create a virus that would spread, he said. “Viability is one thing,” he cautioned. “Whether it’s easily transmissible is another.”
Viruses can change through either mutation of genetic material, or by reassorting with another flu virus. In a research note published in late August on the Web site PloS Currents: Influenza, scientists infected ferrets both with the new H1N1 virus and common seasonal strains of H1N1 and H3N2 flu. The new H1N1 pandemic virus didn’t reassort.
The new virus is lacking certain characteristics that would allow it to mutate to become more virulent, said Nancy Cox, chief of the CDC’s influenza division. “It would be difficult for this virus to acquire some of those known virulence markers,” she said. Whatever any of the experiments show, CDC officials warn against drawing definitive conclusions. “Influenza is really unpredictable,” Cox said.
To find out, scientists at the CDC recently launched experiments in the agency’s labs in which they infected ferrets with both the new H1N1 virus and the highly lethal H5N1 avian flu virus to see if they might “reassort” to create a new hybrid.
The scientists want to know whether a combination of the H1N1 virus -– highly transmissible, but not terribly deadly -– and the H5N1 flu virus could create an easily transmissible, deadly scourge.
The two viruses could mix if they infected the same person simultaneously. While the experiments could produce viable combinations of the two viruses, the real question is whether any could create a virus that would spread, he said. “Viability is one thing,” he cautioned. “Whether it’s easily transmissible is another.”
Viruses can change through either mutation of genetic material, or by reassorting with another flu virus. In a research note published in late August on the Web site PloS Currents: Influenza, scientists infected ferrets both with the new H1N1 virus and common seasonal strains of H1N1 and H3N2 flu. The new H1N1 pandemic virus didn’t reassort.
The new virus is lacking certain characteristics that would allow it to mutate to become more virulent, said Nancy Cox, chief of the CDC’s influenza division. “It would be difficult for this virus to acquire some of those known virulence markers,” she said. Whatever any of the experiments show, CDC officials warn against drawing definitive conclusions. “Influenza is really unpredictable,” Cox said.
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