Figure 1. Specialized personnel killing chickens infected with appropriate equipment to avoid human contagion. Figure taken from chinadaily.com.cn/china/2013h7n9/
The H7N9
influenza virus caused severe human infections and deaths. The virus emerged in
China in 2013. A study carried out by Shi and colleagues evaluated the
evolution of H7N9 viruses isolated from avian species between 2013 and 2017. They
found 23 different genotypes. Surprisingly, some H7N9 viruses acquired an
inclusion of four amino acids in their hemagglutinin (HA). This inclusion
leaded to making the virus lethal in chickens, but not in mice or ferrets. The H7N9
virus rapidly obtained a mutation 627K or 701N in its PB2 segments, causing it
to become extremely lethal to mice and ferrets. In china exist persons that acquired
the H7N9 viruses having the HA insertion and PB2 627K mutation. This study
indicates the capability that new H7N9 mutants have to be lethal to chickens
and the extreme threat they present to humans. The eradication of H7N9 is
immensely important to prevent a pandemic.
Shi J, Deng G, Kong H, Gu C, Ma S, Yin X, et al. (2017). H7N9 virulent mutants detected in chickens in China pose an increased threat to humans, Nature; e-pub ahead of print 24 October 2017, doi: 10.1038/cr.2017.129
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