CIDRAP: Greek H5N6 Virus Appears Distinct From Asian Strain

Credit OIE

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Last Friday, in OIE Notification: HPAI H5N6 In Greece, we learned that an avian flu outbreak originally identified last month as H5N8 was, in fact, HPAI H5N6 - making it the first detection of this particular subtype in Europe.

Unknown on Friday, however, was the lineage of this particular virus. A question I addressed in Friday's blog:

What isn't clear from this report is whether this is a local reassortment - such as we've seen previously from H5N8 (generating H5N5 in Europe & H5N2 in North America) - or if this is the first arrival of  the Asian H5N6 virus, which has been spreading across China, South Korea, Japan, and Vietnam.

  
Last night, Lisa Schnirring - writing for CIDRAP News - shed some light on this question, in a report called:

Greek H5N6 virus appears distinct from Asian strain

Lisa Schnirring | News Editor | CIDRAP News

Mar 06, 2017

In international avian flu developments, scientists said an early look at the highly pathogenic H5N6 strain found recently in Greece suggests that it is different than the one triggering poultry outbreaks in Asia. Elsewhere, agriculture officials in several countries reported more outbreaks involving a variety of subtypes.

Early tests of Greek H5N6 strain

Late last week, Greek officials reported the first H5N6 outbreak to be detected outside of Asia, which involved backyard poultry in the country's northwest. The outbreak began on Feb 6 and was initially and mistakenly reported as H5N8 on Feb 16.

Yesterday, however, a virologist from Europe clarified the findings in comments submitted to ProMED Mail, the online e-mail list of the International Society for Infectious Diseases. Ian Brown, MIBiol, PhD, head of virology at the international reference lab at the Animal and Plant Health Agency in Weybridge, United Kingdom, said the virus doesn't appear to be the same as the current strain in far eastern Asia that has infected both poultry and people.

Writing on behalf of scientists from Greece and the Weybridge lab, Brown said a very preliminary analysis based on limited genetic sequences suggests that it is a result of further reassortment involving highly pathogenic H5N8 and endemic Eurasian viruses. "More details in due course," he added.

(Continue . . . )

Since the emergence of H5N5 (a reassorted spin-off of H5N8) in Europe late last year we've been told  to expect additional reassortments. The  FLI: Updated Risk Assessment On HPAI H5 has warned repeatedly that:

 `Generation of reassortants always must be expected when different high and low pathogenic influenza viruses are circulating in one population.'

While this particular outbreak of H5N6 appears to be a local reassortment, there is little to suggest that the Asian H5N6 (or any other avian subtype currently circulating in Asia), couldn't hitch a ride on migratory birds and begin to spread globally as we have seen already with H5N1 and H5N8.

A scenario the FAO warned about more than two years ago - before H5N8 made its big move into Europe and North America -in FAO-EMPRES Report On The Emergence And Threat Of H5N6.

For reasons that are less than clear, HPAI carriage by migratory birds appears to be on the ascendant these past few months, making the surveillance and study of how they are spreading and evolving of utmost importance.