Tuesday, February 07, 2017

EID Journal: HPAI H5N8 In Migratory Birds - Qinghai Lake, 2016


Four times over the past 11 years (2005-2016) large die offs of migratory birds at Qinghai lake - the largest lake in the People's Republic of China - have figured prominently in the evolution and spread of Highly Pathogenic H5 avian viruses.

The first three involved H5N1, while the most recent - in May of 2016 - was H5N8.

The first - in May of 2005 - heralded the first major expansion of H5N1 beyond Southeast Asia and raised concerns worldwide as pictures of the massive die off of birds went viral (see H5N1 Influenza Continues To Circulate and Change 2006 by Webster et. al.).
Suddenly, and unexpectedly, waterfowl (brown headed gulls, cormorants, ducks, geese, etc.) were dying by the thousands from the H5N1 virus. What emerged at Qinghai Lake - and quickly spread via migratory birds into Europe, Africa, and the Middle east - was clade 2.2 (aka QH05) of the H5N1 virus. 

In 2009 researchers found evidence of another emerging clade  - (2.3.2) - (see 2011 EID Journal New Avian Influenza Virus (H5N1) in Wild Birds, Qinghai, China), found once again in dead birds around the lake.  
As in 2005, in short order the 2.3.2 clade began to show up in migratory birds, and poultry, from Japan to India, supplanting the old 2.2 clade in many regions.
In January of 2015 we saw another `Qinghai-like' die off of birds in China (see H5N1 Detected In Swan Die Off In Henan Province) which was followed a few months later by a die off at Qinghai Lake. This virus was subsequently identified as clade (see Novel H5N1 Reassortment Detected In Migratory Birds - China).

A few months later we learned that the H5N1 virus that reappeared in West Africa in late 2014 after a seven year absence was also clade (see EID Journal: H5N1 In Nigerian Poultry – 2015).

In June of last year, in OIE: Russia - HPAI H5 In Wild & Migratory Birds, we saw a report of a number of birds taken by hunters earlier that month in and around Ubsu-Nur Lake in Russia that had tested positive for HPAI H5.  Some dead birds were also reported.
Three months later it was confirmed by FAO/EMPRES to be H5N8 Clade, which went on to warn  of its potential threat to Europe, the Middle East, and Africa based largely on the events that followed the three previous H5N1 die offs at Qinghai lake.
What we are learning from the EID Journal today is that same virus also turned up at Qinghai Lake in May of 2016, sparking another large die off in waterfowl. This Qinghai/ Ubsu-Nur virus closely matches the H5N8 virus that arrived in Europe last fall (see EID Journal: Reassorted HPAI H5N8 Clade - Germany 2016), sparking the largest avian epizootic in European history.

As studies published in the past few weeks have shown, the H5N8 virus that spread out of Russian and China last summer - while still a clade virus - had changed genetically from the H5N8 viruses that emerged in South Korea and made their way to North America and Europe 2 years ago. 
These new H5N8 viruses - that recently arrived in Europe - are classified as group B (Gochang1-like) of clade,  while the viruses that dominated previously were group A (Buan2-like).
This new group B virus is also a novel reassortant, having acquired genes from several other LPAI avian viruses, all of which probably helps to explain both its increased virulence and transmissibility in wild birds.

I've only excerpted a small portion of the report, so you'll want to follow the link to read it in its entirety.  
Volume 23, Number 4—April 2017

Highly Pathogenic Avian Influenza A(H5N8) Virus in Wild Migratory Birds, Qinghai Lake, China

Mingxin Li1, Haizhou Liu1, Yuhai Bi1, Jianqing Sun1, Gary Wong, Di Liu, Laixing Li, Juxiang Liu, Quanjiao Chen, Hanzhong Wang, Yubang He, Weifeng Shi, George F. Gao, and Jianjun ChenComments to Author


In May 2016, a highly pathogenic avian influenza A(H5N8) virus strain caused deaths among 3 species of wild migratory birds in Qinghai Lake, China. Genetic analysis showed that the novel reassortant virus belongs to group B H5N8 viruses and that the reassortment events likely occurred in early 2016.

Since 2003, the A/Goose/Guangdong/1/96 lineage (Gs/Gd-lineage) of highly pathogenic avian influenza (HPAI) A(H5N1) viruses has been evolving into diverse clades and subclades (1). A novel subclade of HPAI A(H5N8),, which evolved from a clade 2.3.4 H5N1 variant, was initially isolated from domestic ducks in eastern China in 2010 (2) and caused outbreaks in domestic ducks and migratory birds in South Korea in early 2014 (3,4). In late 2014, several countries in Europe and East Asia experienced an invasion of HPAI H5N8 virus (5). This HPAI H5Nx (H5N8, H5N2, and H5N1) lineage subsequently emerged in North America, causing fatalities among wild birds and outbreaks in domestic poultry (5).

Available evidence strongly suggests that the HPAI H5N8 subclade viruses were introduced and spread across the globe by migratory birds (6–8). Currently, 2 distinct H5N8 virus groups have been identified: group A (Buan2-like) and group B (Gochang1-like) (3). Group A H5N8 viruses predominate and have further evolved into 3 distinct subgroups: icA1, icA2, and icA3 (6). We report the emergence of a group B H5N8 virus in Qinghai Lake, China, a key breeding and stopover site for waterfowl along the Central Asian Flyway.



We show that a group B H5N8 virus emerged in Qinghai Lake, China, causing deaths in wild migratory birds. Phylogenetic analysis indicates that the QH-H5N8 virus is the descendant of an unidentified triple-reassortant strain (Figure 2). The reassortment event may have occurred in waterfowl, and can be traced back to early 2016. However, we cannot infer the geographic region where the reassortant virus was generated, because the gene constellation of the virus originated from different locations.

The absence of domestic poultry in the vicinity of Qinghai Lake strongly suggests that the virus was introduced to the area by wild birds. The deaths in Qinghai Lake occurred during May−June 2016, which corresponds with the breeding season for the affected species. In late May 2016, similar H5N8 strains were detected in wild migratory birds at Ubsu-Nur Lake, 1,600 km north of Qinghai Lake (9,10). This finding suggests that the early summer movement of wild migratory birds from unknown southern sites to northern breeding grounds resulted in the introduction of H5N8 to Qinghai Lake and to Ubsu-Nur Lake, infecting a diverse population of breeding waterbirds.

Currently, we know of 3 HPAI H5N1 virus clades that have been introduced to wild migratory birds in Qinghai Lake, which is located near multiple migratory flyways: clade 2.2 in 2005 (11,12), clade 2.3.2 in 2009 (13,14), and clade in 2015 (15). On all 3 occasions, similar viruses were subsequently detected in other regions. Therefore, when wild birds left the breeding location for their wintering sites in the autumn of 2016, H5N8 virus could potentially have spread to other regions along the flyway. HPAI H5N8 viruses have already caused fatalities among wild birds or poultry in South Asia, Europe, the Middle East, and Africa (http://www.oie.int/) since late October 2016. Available genetic information shows that H5N8 strains isolated in other countries are highly similar to the QH-H5N8-like virus, suggesting that the QH-H5N8-like viruses may have already disseminated to other areas along the migratory flyways.
(Continue . . . )

The great advantages that influenza viruses have is their ability to re-invent themselves - via reassortment (antigenic shift) or antigenic drift - allowing them to adapt and survive, even in the face of acquired host immunity or vaccines.
A sobering reminder that Nature's laboratory is open 24/7, it runs millions of simultaneous field experiments every day, and it isn't burdened by red tape, regulations, or budgetary concerns.  

Making influenza a most formidable foe.

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