Friday, May 06, 2016

Arch Virol: Novel Reassortant H6N6 Isolated From Chinese Poultry

Credit NIAID


Until H7N9 unexpectedly emerged as a plausible pandemic threat in early 2013, our avian flu focus was primarily on HPAI H5N1 along with a few H7 viruses of lesser concern.  There were some `also rans' -  like H9N2 - but only H5 and H7 avian viruses were deemed worrisome enough to mandate reporting to the OIE.

As a result, some avian flu viruses get very little attention.

In May of 2013, the Taiwan CDC Reported A Human Infection With Avian H6N1) - the first ever detected - in a 20-year-old female, hospitalized with pneumonia. This was followed in 2014 by the discovery of  Influenza A(H6N1) In Dogs, Taiwan, which surprisingly found a seroprevalence of more than 2% in the dogs tested.

H6N1 has been circulating for decades in Chinese poultry (cite 2002 J Virol  Molecular evolution of H6 influenza viruses from poultry in Southeastern China by Webster, Webby, Shortridge  et al.), and it has been speculated that it may have even been involved in the genesis of H5N1 in Hong Kong in 1997.

Over the past couple of years, we've also seen the emergence of HPAI H5N6 - a reassortment between H5N1 and H6N6 - which has caused more than a dozen illnesses in China, and appears to be spreading in both poultry and wild birds (see EID Journal: Novel Reassortant H5N6 Viruses In Humans, Guangdong China).

After decades of relative obscurity, avian H6 viruses are now a topic of considerable interest to flu researchers (see EID Journal: Seropositivity For H6 Influenza Viruses In ChinaStudy: Adaptation Of H6N1 From Avian To Human Receptor-Binding).

All of which serves as prelude to a study, published a couple of weeks ago in the Archives of Virology, that finds novel reassortant H6N6 avian viruses circulating widely in Chinese poultry.

Once again - as we have with H5N1, H7N9, H10N8, and H5N6 - we find H9N2 (also ubiquitous in Asian poultry) to be involved in the evolution and reassortment of these avian viruses (see  Poultry carrying H9N2 act as incubators for novel human avian influenza viruses).

Although we only have the abstract available, this is another reminder that the constellation of novel avian flu viruses - particularly in China - continues to expand, and that we have more than just H5N1 and H7N9 to keep an eye on.

Arch Virol. 2016 Apr 21. [Epub ahead of print]
Isolation and genetic characterization of novel reassortant H6N6 subtype avian influenza viruses isolated from chickens in eastern China.


H6 subtype avian influenza viruses (AIVs) possess the ability to cross the species barrier to infect mammals and pose a threat to human health.

From June 2014 to July 2015, 12 H6N6 AIVs were isolated from chickens in live-poultry markets in Zhejiang Province, Eastern China. Phylogenetic analysis showed that these isolates received their genes from H6 and H9N2 subtype AIVs of poultry in China.
These novel reassortant viruses showed moderate pathogenicity in mice and were able to replicate in mice without prior adaptation. 

Considering that novel reassorted H6N6 viruses were isolated from chickens in this study, it is possible that these chickens play an important role in the generation of novel reassorted H6N6 AIVs, and these results emphasize the need for continued surveillance of the H6N6 AIVs circulating in poultry.