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Discussion:: H5N1 and Migratory Birds in North America

L

Laidback Al

Well-known member
Yesterday I posted an abstract of a scientific paper that essentially says that highly pathogenic (HP) avian viruses that originate in Asia will only rarely travel to North America with migratory birds. This is based solely on data from two testing locales in North America.

This obviously has implications for the timing and method of arrival of HP H5N1 in North America. Anyone with discussion or comments?
 
Re: Discussion:: H5N1 and Migratory Birds in North America

I think it's not the whole story. Niman has repeatedly shown that polymorphisms in HA and NA, the two outer "key for the lock" protiens, that are found in hi-path AI are already found in swine in North America. Hence my note in the Humor section about flying pigs over the Pacific. The Q subsequences in swine suggest that there is already some low-level interchange, but the big wave hasn't hit. My suspiciion is that, in the time since the Q hi-path line got established, we have simply not had a big El Nino event that would create a huge increase in breeding habitat for mallards and pintails in the area between Alaska and central Canada down the upper Mississippi valley, in the Prairie Pothole geographic region. The dry weather is holding things up. I think we will see it when we get a really good breeding year for the wild ducks.
 
Re: Discussion:: H5N1 and Migratory Birds in North America

Pintails and mallards breed in Alaska - there is no lack of moisture here - there are massive wetlands that have been attracting birds from around the globe for eons.

That being said, global warming is melting some permafrost and we've lost about 10,000 "ponds" and small lakes in the last 30 years. That may force migratory birds to share the habitat, which should INCREASE pathogen exchanges.

UAF ornithologic scientists speculate that disease carrying birds simply don't arrive at their destination because they shut down parts of their immune system as a means of conserving energy for the long trip.

The 2006 Alaska testing did find H3N8 with Indonesian mammalian H5N1 internal segments.

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Re: Discussion:: H5N1 and Migratory Birds in North America

AlaskaDenise said:
That being said, global warming is melting some permafrost and we've lost about 10,000 "ponds" and small lakes in the last 30 years. That may force migratory birds to share the habitat, which should INCREASE pathogen exchanges.
Click to expand...
What this sounds like to me is that breeding conditions have not been optimal for a while.
UAF ornithologic scientists speculate that disease carrying birds simply don't arrive at their destination because they shut down parts of their immune system as a means of conserving energy for the long trip.
Click to expand...
What this sounds like to me is that they think H5N1 isn't getting through.

The 2006 Alaska testing did find H3N8 with Indonesian mammalian H5N1 internal segments.
Click to expand...
What this and Niman's swine travelogs suggest is that it is getting through just fine, and that the testing program has failed to detect it, possibly because the viral load is so low that it is below the threshold of the test. This would be a 'false negative', and would not require the assumption of tinkering with immune systems to explain it.
 
Re: Discussion:: H5N1 and Migratory Birds in North America

What this sounds like to me is that breeding conditions have not been optimal for a while.
Click to expand...
Many species - avian and mammalian are responding by moving further north, where food sources & habitat meet their needs.
What this sounds like to me is that they think H5N1 isn't getting through.
Click to expand...
Yes - but it's a BIG state and they can't test everywhere. They were so confident that it wouldn't be found that they weren't even doing field PCR tests (not good for hunters). However, there have been no unusual bird deaths.

What this and Niman's swine travelogs suggest is that it is getting through just fine, and that the testing program has failed to detect it, possibly because the viral load is so low that it is below the threshold of the test. This would be a 'false negative', and would not require the assumption of tinkering with immune systems to explain it.
Click to expand...
Yes to all of the above.

Thinking about how virus work, they have no reason to invoke the immune evasion mechanism of novel antigens, until the internal parts are all assembled and ready to deliver a high path payload. Influenza is a good poker player. :D Since Alaska has no high volume poultry industry, there is no opportunity/need to develop a strain with polybasic cleavage site.

2 summers ago, I was concerned when some local farmers had sick swine and influenza-infected family members. The piglet supplier to the entire state is in the interior area - beside grain fields and under the Mississippi flyway. The combination of Asian birds, Canadian-H5-infected migratory birds, sick swine, and flu-infected humans could prove an effective mixing vessel for HPAI via migratory birds to reach North America. However, there are only 2 species of Asian birds that come that far into Alaska - one of which prefers hilltops over fields.

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Re: Discussion:: H5N1 and Migratory Birds in North America

AlaskaDenise said:
... HPAI via migratory birds to reach North America. However, there are only 2 species of Asian birds that come that far into Alaska - one of which prefers hilltops over fields.
Click to expand...

I looked up pintails in a guide to ducks, geese, and swans, and found a reference to pintalis bearing Chinese bands found in California. The guy across the back of my cubicle has talked to hunters who have come across other duck bands from China. These birds had to have come over the Aleutians and Coastal Alaska at least to get there.
 
Re: Discussion:: H5N1 and Migratory Birds in North America

Global Patterns of Influenza A Virus in Wild Birds

Bj?rn Olsen,<SUP>1</SUP><SUP>,2</SUP> <NOBR>Vincent J. Munster,<SUP>3</SUP></NOBR> <NOBR>Anders Wallensten,<SUP>4</SUP><SUP>,5</SUP></NOBR> <NOBR>Jonas Waldenstr?m,<SUP>6</SUP></NOBR> <NOBR>Albert D. M. E. Osterhaus,<SUP>3</SUP></NOBR> <NOBR>Ron A. M. Fouchier<SUP>3</SUP><SUP>*</SUP></NOBR>
The outbreak of highly pathogenic avian influenza of the H5N1<SUP> </SUP>subtype in Asia, which has subsequently spread to Russia, the<SUP> </SUP>Middle East, Europe, and Africa, has put increased focus on<SUP> </SUP>the role of wild birds in the persistence of influenza viruses.<SUP> </SUP>The ecology, epidemiology, genetics, and evolution of pathogens<SUP> </SUP>cannot be fully understood without taking into account the ecology<SUP> </SUP>of their hosts. Here, we review our current knowledge on global<SUP> </SUP>patterns of influenza virus infections in wild birds, discuss<SUP> </SUP>these patterns in the context of host ecology and in particular<SUP> </SUP>birds' behavior, and identify some important gaps in our current<SUP> </SUP>knowledge.
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<SUP>Genetic Variation of Influenza Viruses in Wild Birds </SUP>
<SUP>

Evolution of avian influenza viruses in their natural hosts is slow, but not negligible. Avian influenza viruses can be divided into two lineages, Eurasian and American (Fig. 2), probably as a result of long-term ecological and geographical separation of hosts. However, the avifauna of North America and Eurasia are not completely separated; some ducks and shorebirds cross the Bering Strait during migration or have breeding ranges that include both the Russian Far East and northwestern North America (6). The majority of tundra shorebirds from the Russian Far East winter in Southeast Asia and Australia, but some species winter along the west coast of the Americas (22). The overlap in distribution of ducks is not as profound as that of shorebirds, but a few species (e.g., Northern Pintail, Anas acuta) are common in both North America and Eurasia (6) and could also provide an intercontinental bridge for influenza virus. Indeed, influenza viruses carrying a mix of genes from the American and Eurasian lineages have been isolated, indicating that allopatric speciation is only partial (23?25). The partial ecological isolation of influenza virus hosts seems sufficient to facilitate divergent evolution of separate gene pools, but allows occasional spillover of gene segments from one gene pool to the other.
<!-- null -->


<CENTER><TABLE cellSpacing=0 cellPadding=0 width="95%"><TBODY><TR bgColor=#e1e1e1><TD><TABLE cellSpacing=2 cellPadding=2><TBODY><TR bgColor=#e1e1e1><TD vAlign=top align=middle bgColor=#ffffff> </TD><TD vAlign=top align=left>Fig. 2. Phylogenetic tree for the matrix gene of influenza A viruses from a variety of hosts. Nucleotide sequences were selected from public databases and aligned, after which a maximum likelihood tree was generated using influenza virus A/Equine/Prague/57 (H7N7) as outgroup. Sequences were selected from each host to reflect the longest possible time frame and variation in locations of virus isolation. The avian influenza viruses are divided in an American lineage (pink) and a Eurasian lineage (yellow), and there are no clear patterns of host, temporal, or spatial correlation within these lineages. In contrast, the human influenza A virus lineage (light blue), the Eurasian swine lineage (purple), and the HPAI H5N1 lineage (orange) display clear temporal patterns of virus evolution. <NOBR>[View Larger Version of this Image (21K GIF file)]</NOBR> </TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE></CENTER>
<SUP></SUP>
Within each genetic lineage, multiple sublineages of viral genes<SUP> </SUP>cocirculate, but there appear to be no consistent temporal or<SUP> </SUP>spatial correlations. Moreover, genetic data from duck and shorebird<SUP> </SUP>influenza virus isolates from the Americas suggest an active<SUP> </SUP>interplay between these host species (20, 21). Although certain<SUP> </SUP>HA subtypes are reported to be more prevalent in either shorebirds<SUP> </SUP>or ducks in North America, this also does not seem to have resulted<SUP> </SUP>in differences in the genetic composition of influenza viruses<SUP> </SUP>obtained from these two reservoirs (19, 26).
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<SUP></SUP>
</SUP><SUP></SUP>
<SUP></SUP>
<SUP></SUP>
<SUP></SUP>
 
Re: Discussion:: H5N1 and Migratory Birds in North America

wetDirt said:
I looked up pintails in a guide to ducks, geese, and swans, and found a reference to pintalis bearing Chinese bands found in California. The guy across the back of my cubicle has talked to hunters who have come across other duck bands from China. These birds had to have come over the Aleutians and Coastal Alaska at least to get there.
Click to expand...

The area I'm referring to (Delta Junction) is in the Interior part of Alaska, with no connection to the Pacific flyway (Aleutians & Coastal AK).

Yes, I've heard of birds going both ways - I wonder what % do that?

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Re: Discussion:: H5N1 and Migratory Birds in North America

After giving this more thought, I realized that other migratory species are very adherant to a particular territory. Perhaps that's why they don't mix with their other-hemisphere friends.

Caribou stay within a given herd their entire migratory route and rarely (occasionally a juvenile male) mix with other herds. Same with Salmon - those born in a particular stream will swim up a precise unique route along major rivers to return to their spawning areas. I've helped plot bear territories and they are remarkably unique & consistant, especially when it comes to creekside fishing spots.

So if birds usually follow the same logic -voila - no pathogen gift exchanges with their Asian cousins.

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Re: Discussion:: H5N1 and Migratory Birds in North America

AlaskaDenise said:
Global Patterns of Influenza A Virus in Wild Birds

...
Phylogenetic tree for the matrix gene of influenza A viruses from a variety of hosts. Nucleotide sequences were selected from public databases and aligned, after which a maximum likelihood tree was generated using influenza virus A/Equine/Prague/57 (H7N7) as outgroup. Sequences were selected from each host to reflect the longest possible time frame and variation in locations of virus isolation. The avian influenza viruses are divided in an American lineage (pink) and a Eurasian lineage (yellow), and there are no clear patterns of host, temporal, or spatial correlation within these lineages. In contrast, the human influenza A virus lineage (light blue), the Eurasian swine lineage (purple), and the HPAI H5N1 lineage (orange) display clear temporal patterns of virus evolution. <NOBR
Click to expand...


Well, nuts, they don't include North American Swine, where there is a lot of action with ducks. Wonder why not?
 
Re: Discussion:: H5N1 and Migratory Birds in North America

article was dated: 21 April 2006 > Olsen et al. , pp. 384 - 388

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Re: Discussion:: H5N1 and Migratory Birds in North America

niman niman is offline
Resident

Join Date: Feb 2006
Posts: 8,126
Default Re: Wild Duck H5N2 Sequence from Canada
Quote:
Originally Posted by AlaskaDenise
I assume that's the swine with human H3N2 Neuraminidase?

Are we brewing a unique American BF?

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No, its H1N2

DQ826532 A/mallard/BC/373/2005 2005 H5N2
DQ280250 A/swine/Ontario/11112/04 2004 H1N1
DQ447187 A/swine/Taiwan/CO935/2004 2004 H1N2
DQ431990 A/swine/Taiwan/CO935/2004 2004 H1N2
AY129156 A/Swine/Korea/CY02/02 2002 H1N2
AY233393 A/Duck/NC/91347/01 2001 H1N2
DQ058215 A/swine/Guangdong/2/01 2001 H1N1
AF455682 A/Swine/Illinois/100084/01 2001 H1N2
AF455681 A/Swine/Illinois/100085A/01 2001 H1N2
AF455679 A/Swine/Iowa/930/01 2001 H1N2
AY060050 A/Swine/MN/16419/01 2001 H1N2
AY060048 A/Swine/MN/23124-S/01 2001 H1N2
AY060047 A/Swine/MN/23124-T/01 2001 H1N2
AY060051 A/Swine/MN/34893/01 2001 H1N2
AF455677 A/Swine/North Carolina/93523/01 2001 H1N2
AF455675 A/Swine/Ohio/891/01 HA (4) 2001 H1N2
AF455680 A/Swine/Indiana/P12439/00 2000 H1N2
AF455678 A/Swine/Minnesota/55551/00 2000 H1N2
AF250124 A/Swine/Indiana/9K035/99 1999 H1N2
AF222035 A/Swine/Wisconsin/458/98 1998 H1N1
AF222036 A/Swine/Wisconsin/464/98 1998 H1N1
AF222026 A/Swine/Wisconsin/125/97 1997 H1N1
AF222027 A/Swine/Wisconsin/136/97 1997 H1N1
AF222032 A/Swine/Wisconsin/235/97 1997 H1N1
AF222033 A/Swine/Wisconsin/238/97 1997 H1N1
U53162 A/Wisconsin/4754/94 1994 H1N1
U53163 A/Wisconsin/4755/94 1994 H1N1
S67220 A/Swine/Nebraska/1/92 1992 H1N1
L09063 A/Swine/Nebraska/1/92 1992 H1
L24362 A/Maryland/12/91 1991 H1N1
U46783 A/Swine/Beijing/47/91 1991 H1N1
U11857 A/Swine/St-Hyacinthe/106/91 1991 H1
M81707 A/Swine/Indiana/1726/88 1988 H1N1
DQ508905 A/Wilson-Smith/1933 1933 H1N1
J02176 A/WSN/33 1933 H1N1
Click to expand...

There are lots of examples of sequences flipping from N.Am swine to people to birds. Now the quoted paper looked at the matrix protein, which perhaps is more conserved than H and NA, I don't remember exactly but I think most of the variability is on the surface protiens.
 
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