[editing is mine]
November 19, 2012
CIDRAP
Most H5N1 avian influenza viruses in Egypt have two mutations that may
make them more transmissible in mammals, thus posing a greater threat of
sparking a human pandemic than H5N1 viruses elsewhere, according to
experts whose research on H5N1 transmissibility sparked a major
controversy in the past year. The finding was reported by Ron Fouchier,
PhD, Yoshihiro Kawaoka, DVM, PhD, and three other authors in an opinion
article published last week in PLoS Pathogens. Their conclusion
was based on an inspection of publicly available hemagglutinin (HA)
sequences from H5N1 viruses. Fouchier led a team that showed that as few
as five mutations could give H5N1 viruses airborne transmissibility in
ferrets, and Kawaoka's team showed that a hybrid virus containing H5 HA,
with certain mutations, also could be an airborne spreader in ferrets.
The studies were published in May and June after a long debate in
science and
government circles about whether the details should be released.
The studies revealed, among other things, that a mutation involving loss
of a glycosylation site at HA positions 154-156 appears to be critical
for H5 virus transmission in mammals, according to the PLoS Pathogens
article. When the team examined available HA sequences from avian H5N1
viruses, they found that more than 70% of Egyptian isolates lacked the
HA 154-156 glycosylation site, versus about 25% of isolates from Vietnam
and none from Indonesia. An analysis of human isolates from the three
countries revealed a similar pattern. In addition, the researchers say
the mutation PB2-627K, which is known to be involved in mammalian
adaptation of avian flu viruses, is found in most H5N1 isolates from
Egypt.
Nov 15 PLoS Pathogens article
http://www.cidrap.umn.edu/cidrap/content/influenza/avianflu/news/nov1912fluscan.html
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