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Commentary
Low Reactor G158E In
2010 Swine Pandemic H1N1
Recombinomics
Commentary 12:50
March 11, 2010
Both sequences have a collection date of February 26, 2010, which represents the most current public 2010 pandemic H1N1 sequence and the first examples of G158E in swine pandemic H1N1. This polymorphism has been linked to a “low reactor” designation by Mill Hill and the CDC. It is also in the antigenic site associated with immunological escape from neutralizing monoclonal antibodies which react with 1918 and 2009 pandemic H1N1. The number of reported sequences with G158E is on the rise in Asia and Europe. Examples have also been reported in the United States although CDC has reported these examples as California/7 like, raising questions about recent antigenic characterizations. WHO has acknowledged inter-lab differences and has proposed a new standard using pooled human antibodies, which may produce uniform test results with lowered sensitivity.
The detection of G158E in February swine H1N1 isolates provides additional signals that the rate of H1N1 evolution is increasing. These sequences have D1381G, which is widely detected in human sequences including those in Ukraine and Norway with D225G (see list here). However, the Minnesota swine isolates have a number of non-synonymous changes which are largely limited to swine isolates See list here here here here). These may be present in human 2010 sequences, but release of such sequences is significantly delayed, and only a handful of human 2010 sequences have been released. The largest number were just released by Greece, and 3/9 had D225G, which is another polymorphism being reported at increasing frequencies.
The latest sequence from China, A/Beijing/22811/2009, was also just released. The December, 2009 isolate has 9 recently acquired non-synonymous changes in HA, once again signaling increased H1N1 evolution.
As H1N1 evolution is increasing, antigenic characterization tests are increasingly suspect. Similarly, the number of samples being collected and the release of data is on a decline, while the start of a new wave is being signalled.
The current degrading H1N1 surveillance is becoming increasingly hazardous to the world’s health.
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