Flu News: What is the significance of D225G?
by ilene - November 25th, 2009 4:28 pm
Swine Flu News: What is the significance of D225G?
By Ilene
With the current rush of news about the swine flu virus morphing into more aggressive lung-shredding and tamiflu-resistant mutants, there is some confusion as to why these changes are being seen in people in "hotspots" around the world, with no clear connection to each other. Officials at the WHO and CDC suggest that the same mutations are arising spontaneously in multiple locations but this doesn’t quite make sense. To better understand how changes in the swine flu virus may be occurring, I contacted Dr. Henry L. Niman, founder and president of Recombinomics. Dr. Niman has been an active researcher in the evolution of flu virus. His latest thoughts on the ongoing progression of the flu pandemic may be found at his website, Recombinomics.
For a little background, the D222G mutation or D225G mutation (same mutation, different numbering system) was found in three cases in Norway ("Norway" mutation), and in other countries, including Brazil, China, Japan, Mexico, Ukraine, the United States, and more recently Hong Kong. The change in a single nucleotide results in an amino acid change in the virus’s receptor binding protein. This has the effect of allowing the virus to bind receptors in the lung tissue, rather than the more usual binding to cells in the upper airways. Theoretically, this may confer greater virulence to the virus, potentially leading to more severe disease as the infection invades deeper in the respiratory tract. This change was also seen in the 1918 flu pandemic, in some (but not all) cases.
Recombinomics
The name of Dr. Niman’s company "Recombinomics" is taken from the word "recombine" or "recombination" – the driver of rapid molecular evolution and the emergence of infectious agents. Recombination* is a mechanism whereby small bits of genetic information pass between viruses so that a virus may quickly acquire a genetic change that evolved previously over the years in other viruses. Recombination is similar to reassortment, but with less genetic material being exchanged.
Sporadic mutations do not usually lead to successful adaptive changes – often they have no effect or prove to be non-adaptive, with the mutation failing to be further replicated. In contrast, recombination allows viruses to quickly alter their characteristics by acquiring genetic material that already exists in the viral reservoir (i.e., the pool of viruses circulating in a population). This…