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Commentary
Severe and Fatal H1N1 Cases Increase In Chihuahua Mexico
Recombinomics
Commentary 01:30
April 7, 2011
24 people have been reported in hospitals in the Health Services Chihuahua, four in hospitals belonging to the Chihuahua Institute of Health, one was attended in the ISSSTE, 11 by the IMSS and 5 in private clinics.
The municipalities that have more cases are Chihuahua and Ciudad Juarez with 17 to 28 respectively .
The above translation describes the 45 lab confirmed H1N1 cases in Chihuahua, Mexico. Not included is the first fatality (26M) who was the partner of the first lab confirmed fatality (36M). These two fatalities were part of a cluster of cases in the traffic department in Juarez, which also included a critical case. The HA and NA sequences from the fatal case (36M) were recently released and the HA sequence, A/Mexico/InDRE1945/2011, contains D225N. Two other HA sequences, (A/Mexico/InDRE1946/2011 and A/Mexico/InDRE1947/2011), from nonfatal cases were also released. They were closely related to the fatal case, but neither had D225N. One exactly matched with fatal cases with the exception of D225N. The other sequence had two synonymous differences. Thus, at the protein level all three sequences were identical, other than the presence of D225N in the fatal case. One of the newly acquire polymorphisms in this sub-clade was A189T.
Thus, there major sub-clade circulating in North America had S186P, S188T, or A189T. The changes, which are adjacent to receptor binding position 190 are similar to changes in seasonal H1N1 which emerged in 2008. Virtually all isolates had A193T along with at least one change at positions 187, 189, or 196, raising concerns that the changes in pandemic H1N1 will facilitate immunological escape.
In the fatal case, the combination of A189T with D225N is similar to the H3N2 combination of S193F and D225N, which is the combination that drove the fixing of adamantine resistance (S31N in M2) and has been dominant in H3N2 ever since.. Thus, the H1N1 combination may lead to dominance of that sub-clade, and D225N on a pandemic H1N1 background may lead to more severe and fatal cases as seen in the recently released sequence. Moreover, the presence of D225N in the nasopharyngeal swab sample may signal increased transmission. In the Ukraine, D225N and D225N were frequently detected in lung autopsy samples.
The high frequency of hospitalized and fatal cases is supported by the above figures for Chihuahua. More sequences from these severe and fatal cases would be useful.
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