# 4070
In an announcement today Hong Kong authorities tell of a year-old boy hospitalized for 3 days last July who tested positive for the same mutation in the H1N1 virus as made headlines last week.
The amino acid change in the HA1 gene at position 222 (225 in influenza H3 numbering) from aspartic acid (D) to glycine (G) had been found in three cases of severe pandemic Influenza in Norway.
The assumption by some has been that this mutation must increase the virulence of the virus because it was found in several severe cases in Norway, some with fatal outcomes.
While it may indeed prove to be a factor in the virulence of H1N1, what we don’t have a good handle on is how many mild cases have occurred with this mutation?
Without knowing that, it is very difficult to assess the relative dangers of this single amino acid substitution.
The case announced today would appear only to have been of moderate severity, as the child was only hospitalized for 3 days and has fully recovered.
The other key point here is that of 123 samples tested in Hong Kong, only one showed the mutation.
Which would suggest it isn’t widespread in that community, and may simply be a spontaneous mutation.
Also, the boy’s family did not fall ill, and the virus remained sensitive to antivirals.
The significance of this mutation is not yet clear. But each day brings us more data which will hopefully give us a better idea in the weeks and months to come.
Two reports:
H1N1 flu virus mutation detected in HK
www.chinaview.cn
2009-11-24 07:33:52
HONG KONG, Nov. 23 (Xinhua) -- Hong Kong's Department of Health announced Monday that it had found the same mutation in a H1N1 flu virus sample as the one detected in Norway recently.
The department said that it had examined the genetic sequence of H1N1 flu viruses in its monitoring system. Out of the 123 sequences studied, one sample showed the same mutation as the Norway strain.
The virus was taken from a year-old boy who developed flu-like symptoms July 22. He was admitted to Prince of Wales Hospital July25 and discharged three days later. He has recovered.
Mutations are frequently encountered in influenza viruses. According to the World Health Organization, the same mutation of the virus has been found on the Chinese mainland and in other countries, including Brazil, Japan, Mexico, Ukraine and the United States.
The virus with this mutation remained sensitive to antiviral drugs, Tamiflu and Relenza. No evidence suggests these mutations are leading to an unusual increase in the number of H1N1 flu infections or a greater number of severe or fatal cases.
And an excerpt from the Hong Kong Standard
Mutated swine flu found in tot
Mary Ann Benitez
Tuesday, November 24, 2009
EXCERPT
The Department of Health announced last night that it found the same mutation in the boy, who developed symptoms on July 22 and tested positive for the virus on July 25 when he was admitted to Prince of Wales Hospital.
He was discharged on July 28 and recovered completely. His family members did not fall ill.
A department spokesman said: "The virus with this mutation remained sensitive to antiviral drugs oseltamivir [Tamiflu] and zanamivir [Relenza]."
The spokesman said there is no evidence that these mutations are leading to an unusual increase in the number of swine flu infections or a greater number of severe or fatal cases.
<SNIP>
Stene-Larsen added: "Based on what we know so far, it seems that the mutated virus does not circulate in the population, but might be a result of spontaneous changes."
