Swine flu virus may not be the virulent type
Diana Clarke
The H1N1 swine flu may not be the virulent type of strain that has caused severe pandemics in the past, suggest researchers. Based on the genetic sequence of the H1N1 swine virus, when compared to the 1918 and the H5N1 avian virus, “There’s an amino acid missing in this, suggesting this may not be in its current form as lethal as some feared,” said Tim Johnson, M.D., ABC News. In addition, the current swine flu may be similar to the one that occurred in 1957 which is probably why older people with immunity haven’t become ill, said Dr. Johnson.
The H1N1 swine virus is so named based on the two proteins, Hemagglutinin (H) and neuraminidase (N), that are located on the exterior of the virus and bind to the host, allowing the virus to replicate.
The H1N1 flu virus attaches to receptors in the host’s nose and throat and causes the virus to spread easily through coughing and sneezing. On the other hand, the H5N1 avian flu virus attaches to receptors in the lungs, also spreading readily among birds, but only in rare instances, this virus infects humans. H1N5 can cause illness, such as pneumonia.
The other encouraging news involves the influenza A virus NS1 protein that binds to the human CPSF30 protein. The NS1 protein in the H1N1 swine flu virus does not appear to cause a strong immune response.
However, the NS1 protein has the potential to elicit an immune response in which case antibodies, the white blood cells-- T-cells and macrophages—flood the site of infection repeatedly. In the lungs, this action can be potentially lethal due to extreme inflammation, which can block the airways.
Researchers at the University of Texas at Austin and Rutgers University have discovered that altering an amino acid rendered the NS1 binding pocket incapable of attaching to the human host cell.
“These experiments validate the NS1 pocket as a target for antiviral drug discovery,” said Robert M. Krug, professor and chair of molecular genetics and microbiology, University of Texas at Austin.
Each year, up to 20% of the US population come down with the flu, and
the flu virus kills 36,000.
But in a Los Angeles Times article, Richard Webby, an influenza virologist at St. Jude Children’s Research Hospital, said: “This virus doesn't have anywhere near the capacity to kill like the 1918 virus.”
Yet scientists remain concerned. The 1918 virus was mild at first but returned months later as a lethal strain.
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Last modified: 05/01/09
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