Influenza A (H5N6) Virus has reassorted (again)

Avian influenza A(H5N6) viruses have circulated among poultry in southern (Jiangxi, Guangdong) and western (Sichuan) provinces of China since 2013. In 2014, outbreaks of H5N6 virus infection occurred among poultry in China, Laos and Vietnam. In April 2014, the first case of highly pathogenic H5N6 infection among humans was detected in Sichuan Province; the second case was detected in December 2014 in Guangdong Province. In December 2015, four humans in Guangdong Province were infected with Influenza A (H5N6) Virus.

Since emerging in 2013, Influenza A (H5N6) Virus has managed to reassort with both Influenza A (H9N2) Virus and Influenza A (H6N6) Virus in Guangdong (China). Two of the three isolates examined also appear to have picked up genes for amantadine (an older antiviral) resistance, that was not present in 2014[1].

The authors suggested there may be other - as yet undetected - H5N6 reassortants in the wild and others may yet emerge.

Then, during the last week of November 2016, Korea's Ministry of Agriculture released a preliminary genetic analysis of four recently obtained Influenza A (H5N6) Virus samples from South Korean wild duck's feces and compared them to the same virus subtypes collected previously from Mainland China and Hong Kong[2].

The analysis showed the Korean Influenza A (H5N6) Virus has changed internally from its predecessors, and that its genetic evolution continues unabated. While Korea's Influenza A (H5N6) Virus' HA and NA genes are roughly a 99% match to earlier samples, some if its internal genes have changed - likely through reassortment - and at least one (PA gene) is only about a 92% match to previous samples. It seems very likely that the virus picked up these changes as it circulated among birds in their summer breeding areas of Siberia and Northern China.

Exactly how these genetic changes might affect the behavior of the virus – if at all – isn't yet known, although Korea's CDC is conducting tests to determine its potential pathogenicity in humans.


[1] Novel Reassortant Avian Influenza A(H5N6) Viruses in Humans, Guangdong, China, 2015 in Emerging Infectious Diseases – 2016
[2] MARFA: H5N6 type AI virus gene analysis Intermediate results (November 28th, 2016)