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**HenryN** · December 19, 2007, 12:01 PM

Re: New swine flu has avian flu genes

New Swine Flu Has Avian Flu Genes

By Staff
(AXcess News) Washington - Researchers have identified a new strain of swine influenza--H2N3--which belongs to the group of H2 influenza viruses that last infected humans during the 1957 pandemic. This new strain has a molecular twist: It is composed of avian and swine influenza genes.
Agricultural Research Service (ARS) veterinarians Juergen Richt, Amy Vincent, Kelly Lager and Phillip Gauger conducted this research with Iowa State University (ISU) visiting scientist Wenjun Ma, ISU veterinarian Bruce Janke and other colleagues at the University of Minnesota and St. Jude Children?s Research Hospital. The ARS veterinarians work at the agency's National Animal Disease Center in Ames, Iowa.
The research team studied an unknown pathogen that in 2006 infected two groups of pigs at separate production facilities. Both groups of pigs used water obtained from ponds frequented by migrating waterfowl.
Molecular studies indicated the unknown pathogen was an H2N3 influenza virus that is closely related to an H2N3 strain found in mallard ducks. But this was the first time it had been observed in mammals.
Influenza viruses have eight gene segments, all of which can be swapped between different virus strains. Two of these gene segments code for virus surface proteins that help determine whether an influenza virus is able to infect a specific host and start replicating--the first step in the onset of influenza infection.
In the newly isolated swine H2N3, the avian H2 and N3 gene segments mixed with gene segments from common swine influenza viruses. This exchange--and additional mutations--gave the H2N3 viruses the ability to infect swine. Lab tests confirmed that this strain of H2N3 could also infect mice and ferrets.
These findings provide further evidence that swine have the potential to serve as a "mixing vessel" for influenza viruses carried by birds, pigs and humans. It also supports the need to continue monitoring swine--and livestock workers--for H2-subtype viruses and other influenza strains that might someday threaten swine and human health.
Results of this study were published online this week in the Proceedings of the National Academy of Sciences of the United States of America.
ARS is the U.S. Department of Agriculture's chief scientific research agency.

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**HenryN** · December 19, 2007, 12:04 PM

Re: New swine flu has avian flu genes

Published online before print December 18, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0710286104

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MICROBIOLOGY
Identification of H2N3 influenza A viruses from swine in the United States
Wenjun Ma*,, Amy L. Vincent, Marie R. Gramer, Christy B. Brockwell,?, Kelly M. Lager, Bruce H. Janke*, Phillip C. Gauger, Devi P. Patnayak, Richard J. Webby, and J?rgen A. Richt,||
*Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011; Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Ames, IA 50010; Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Minnesota , St. Paul, MN 55108; St. Jude Children's Research Hospital, Memphis, TN 38018; and ?Interdisciplinary Program, University of Tennessee Health Science Center, Memphis, TN 38163
Communicated by Robert G. Webster, St. Jude Children's Research Hospital, Memphis, TN, October 31, 2007 (received for review August 30, 2007)
Abstract
Although viruses of each of the 16 influenza A HA subtypes are potential human pathogens, only viruses of the H1, H2, and H3 subtype are known to have been successfully established in humans. H2 influenza viruses have been absent from human circulation since 1968, and as such they pose a substantial human pandemic risk. In this report, we isolate and characterize genetically similar avian/swine virus reassortant H2N3 influenza A viruses isolated from diseased swine from two farms in the United States. These viruses contained leucine at position 226 of the H2 protein, which has been associated with increased binding affinity to the mammalian 2,6Gal-linked sialic acid virus receptor. Correspondingly, the H2N3 viruses were able to cause disease in experimentally infected swine and mice without prior adaptation. In addition, the swine H2N3 virus was infectious and highly transmissible in swine and ferrets. Taken together, these findings suggest that the H2N3 virus has undergone some adaptation to the mammalian host and that their spread should be very closely monitored. 

avian | reassortant | interspecies transmission
<HR align=left width="50%" noShade SIZE=1>Footnotes

Author contributions: W.M., A.L.V., K.M.L. and J.A.R. designed research; W.M., A.L.V., M.R.G., C.B.B., K.M.L., B.H.J., P.C.G., D.P.P., R.J.W. and J.A.R. performed research; W.M., A.L.V., M.R.G., K.M.L., B.H.J., R.J.W. and J.A.R. analyzed data; and W.M., A.L.V., M.R.G., K.M.L., R.J.W. and J.A.R. wrote the paper. 
The authors declare no conflict of interest. ||To whom correspondence should be addressed at: National Animal Disease Center, 2300 Dayton Avenue, Ames, IA 50010. E-mail: juergen.richt@ars.usda.gov

**HenryN** · December 19, 2007, 12:18 PM

Re: New swine flu has avian flu genes

Data deposition: The sequences reported in this paper have been deposited in the GenBank
database [accession nos. EU258935–EU258942 (A/Sw/2124514) and EU258943–EU258950

(A/Sw/4296424)].

**Shannon Bennett** · December 19, 2007, 12:25 PM

Re: New swine flu has avian flu genes

PubMed

http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&uid=7684877&cmd=showdetailview&indexed=google

PubMed® comprises more than 39 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full text content from PubMed Central and publisher web sites.

<INPUT id=UidCheckBox type=checkbox value=7684877 name=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPa nel.Pubmed_RVAbstractPlus.uid sid="1">1: Virology. 1993 Jun;194(2):781-8. <SCRIPT language=JavaScript1.2></SCRIPT>Links
<DD class=abstract>Origin of the pandemic 1957 H2 influenza A virus and the persistence of its possible progenitors in the avian reservoir.

Sch?fer JR, Kawaoka Y, Bean WJ, S?ss J, Senne D, Webster RG.
St. Jude Children's Research Hospital, Department of Virology/Molecular Biology, Memphis, Tennessee 38105.
H2N2 influenza A viruses caused the Asian pandemic of 1957 and then disappeared from the human population 10 years later. To assess the potential for similar outbreaks in the future, we determined the antigenicity of H2 hemagglutinins (HAs) from representative human and avian H2 viruses and then analyzed the nucleotide and amino acid sequences to determine their evolutionary characteristics in different hosts. The results of longitudinal virus surveillance studies were also examined to estimate the prevalence of avian H2 isolates among samples collected from wild ducks and domestic poultry. Reactivity patterns obtained with a large panel of monoclonal antibodies indicated antigenic drift in the HA of human H2 influenza viruses, beginning in 1962. Amino acid changes were clustered in two regions of HA1 that correspond to antigenic sites A and D of the H3 HA. By contrast, the antigenic profiles of the majority of avian H2 HAs were remarkably conserved through 1991, resembling the prototype Japan 57 (H2N2) strain. Amino acid changes were distributed throughout HA1, indicating that antibodies do not play a major role in the selection of avian H2 viruses. Phylogenetic analysis revealed two geographic site-specific lineages of avian H2 HAs: North American and Eurasian. Evidence is presented to support interregion transmission of gull H2 viruses. The human H2 HAs that circulated in 1957-1968 form a separate phylogenetic lineage, most closely related to the Eurasian avian H2 HAs. There was an increased prevalence of H2 influenza viruses among wild ducks in 1988 in North America, preceding the appearance of H2N2 viruses in domestic fowl. As the prevalence of avian H2N2 influenza viruses increased on turkey farms and in live bird markets in New York City and elsewhere, greater numbers of these viruses have come into direct contact with susceptible humans. We conclude that antigenically conserved counterparts of the human Asian pandemic strain of 1957 continue to circulate in the avian reservoir and are coming into closer proximity to susceptible human populations.
PMID: 7684877 [PubMed - indexed for MEDLINE]
</DD>

**Shannon Bennett** · December 19, 2007, 12:32 PM

Re: New swine flu has avian flu genes

http://vir.sgmjournals.org/cgi/content/full/80/12/3167

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Transmission of Eurasian avian H2 influenza virus to shorebirds in North America

N. V. Makarova1,2, N. V. Kaverin1, S. Krauss2, D. Senne3 and R. G. Webster2

The D. I. Ivanovsky Institute of Virology, Gamaleya Str. 16, Moscow 123098, Russia1
St Jude Children?s Research Hospital, Department of Virology and Molecular Biology, 332 N. Lauderdale, Memphis, Tennessee 38105, USA2
Avian Viruses Section, Diagnostic Virology Laboratory, National Veterinary Service Laboratories, APHIS, United States Department of Agriculture, PO Box 844, Ames, Iowa 50010, USA3

Author for correspondence: Natalia Makarova (at The D. I. Ivanovsky Institute of Virology). Fax +7 095 5165314. e-mail finmed@glasnet.ru<SCRIPT type=text/javascript></SCRIPT>

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Influenza A virus of the H2 subtype caused a serious pandemic in 1957 and may cause similar outbreaks in the future. To assess the evolution and the antigenic relationships of avian influenza H2 viruses, we sequenced the haemagglutinin (HA) genes of H2 isolates from shorebirds, ducks and poultry in North America and derived a phylogenetic tree to establish their interrelationships. This analysis confirmed the divergence of H2 HA into two geographical lineages, American and Eurasian. One group of viruses isolated from shorebirds in North America had HA belonging to the Eurasian lineage, indicating an interregional transmission of the H2 gene. Characterization of HA with a monoclonal antibody panel revealed that the antigenicity of the Delaware strains differed from the other avian strains analysed. The data emphasizes the importance of avian influenza surveillance. 

<TABLE cellSpacing=0 cellPadding=0 width="100%" bgColor=#e1e1e1><TBODY><TR><TD vAlign=center align=left width="5%" bgColor=#ffffff></TD><TH vAlign=center align=left width="95%"> Main text </TH></TR></TBODY></TABLE><TABLE cellPadding=5 align=right border=1><TBODY><TR><TH align=left>TOP
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Influenza is a re-emerging epidemic disease, and during the last century there have been several human pandemics. Three influenza virus subtypes, H1N1, H2N2 and H3N2, were associated with these pandemics. Seroarcheological data suggest that H2 influenza virus was responsible for the influenza pandemic of 1889?1890 (Mulder & Masurel, 1958 ). There are no indications that influenza A viruses of the H2 subtype circulated in the human population during the 20th century until 1957, when there was a serious H2 influenza pandemic. The pandemic virus had haemagglutinin (HA), NA and PB1 genes derived from an H2N2 avian precursor; the remainder of its genes were derived from an H1N1 virus that circulated in the human population before 1957 (Kawaoka et al., 1989 ; Scholtissek et al., 1978 ). 
Influenza viruses of the H2 subtype circulated in the human population until 1968, after which they continued to be detected in avian populations (Tumova et al., 1975 ; Shortridge, 1979 ; Sinnecker et al., 1983 ; Wright et al., 1992 ). Most H2N2 viruses in wild and domestic birds are antigenically closely related to the viruses that circulated in the human population between 1957 and 1968, suggesting that viruses similar to the progenitor of the Asian/57 pandemic are still circulating in birds (Schafer et al., 1993 ). Serological data showed that the percentage of detection of anti-H2 antibodies in the sera of adults was low, and no anti-H2 antibodies were detected in the sera of children (Govorkova et al., 1993 ). These facts emphasize the importance of periodical surveillance of avian H2 influenza viruses and elucidation of the phylogenetic and evolutionary relationships among present and previously known avian H2 influenza viruses. 
The two distinct lineages of avian H2 influenza viruses, American and Eurasian, are distinguished by their geographical origins (Schafer et al., 1993 ). One virus isolated in the USA, A/Herring gull/Delaware/677/88, has been shown to belong to the Eurasian lineage, but that single observation could not be conclusively interpreted. To elucidate the evolutionary characteristics of recently isolated avian viruses of the H2 subtype, we investigated the antigenic and phylogenetic relationships among recent and previously described avian influenza H2 viruses. 
The viruses used in these studies (Table 1) were obtained as part of surveillance programs in the northeastern part of the USA and in Alberta, Canada, or from the virus repository at St Jude Children?s Research Hospital, Memphis, TN, USA. The shorebird and gull viruses were isolated from samples collected annually in mid-May from the Delmarva Peninsula region of the USA between 1985 and 1998 (Kawaoka et al., 1988 ). Influenza viruses from migratory ducks were isolated between 1977 and 1997 from samples collected annually in late July to early September in Alberta, Canada (Sharp et al., 1993 ). Viruses were propagated at low m.o.i. in the allantoic cavity of 11-day-old embryonated chicken eggs. 

<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>View this table:
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 </TD><TD vAlign=top align=left>Table 1. Influenza A viruses used for phylogenetic analysis
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Phylogenetic analysis was based on the nucleotide sequences of 15 newly sequenced HA genes (HA1 subunit) and the previously sequenced HA genes of avian H2 viruses (Table 1). The sequences were determined by reverse transcription (Huddleston & Brownlee, 1982 ), and PCR direct sequencing was performed by the Centre for Biotechnology at St Jude Children?s Research Hospital by using dye-terminator Cycle-Sequencing Ready-Reaction kits with AmpliTaq DNA polymerase FS (Perkin-Elmer, Applied Biosystems). Sequence data of each gene were analysed by the Wisconsin Package version 9.0, Genetics Computer Group, Madison, WI, USA. Phylogenetic analysis of new sequences, together with sequences from GenBank, was performed by a combination of the Neighbour-Joining method (Saitou & Nei, 1987 ) for detection of distances and the Maximum-Parsimony method (Fitch, 1970 ) for generation of a phylogenetic tree using PHYLIP (the PHYLogeny Inference Package) version 3.57c. The phylogenetic tree is rooted to the H5 HA1 sequence from A/Chicken/Pennsylvania/1/83 (H5N1) (J04325) because of the high similarity (74%) between H2 and H5 serotypes (Air, 1981 ; Nobusawa et al., 1991 ). 

The phylogenetic tree (Fig. 1) confirms the divergence of H2 influenza A viruses into two distinct geographical lineages: American and Eurasian. All newly sequenced HA1 genes from domestic poultry were of the American lineage. However, a large group of recent American isolates from shorebirds in Delaware Bay belonged to the Eurasian lineage. As reported previously (Schafer et al., 1993 ), the A/Herring gull/Delaware/677/88 strain isolated in Delaware Bay also is of the Eurasian lineage. Together, the viruses isolated in Delaware Bay composed a divergent sublineage in the Eurasian section of the tree. All of these viruses were isolated from seabirds (gulls and shorebirds). Interestingly, two viruses previously isolated from gulls in North America (A/Gull/Maryland/19/77 and A/Laughing gull/New Jersey/75/85) were of the American lineage but diverged from other isolates of that lineage. A/Peking duck/Potsdam/1689-4/85 was the Eurasian virus most closely related to the group of American viruses with Eurasian HA. These data suggest that Eurasian H2 was transmitted from Eurasian to American avian hosts. 

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 </TD><TD vAlign=top align=left>Fig. 1. Phylogenetic tree of the HA1 genes of H2 influenza A viruses. The tree is rooted to the H5 HA sequence from A/Chicken/Pennsylvania/1/83 (accession no. J04325). Horizontal distances are proportional to the number of nucleotide changes in HA1. Strain abbreviations are listed in Table 1.
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The rates of evolution were determined from the nucleotide sequences of the HA1 of H2 influenza viruses using GeneDoc (Multiple sequence alignment editor and shading utility version 2.3000, 1997) for statistical analysis of the relationships between pairs of sequences. In the Delaware Bay group of viruses, the evolution rate was 2?47?0?23 nucleotide substitutions per year, a rate significantly greater than that of the Eurasian viruses (1?57?0?23 substitutions per year) but less than that of the American viruses (3?8?0?5 substitutions per year). The differences are statistically significant at P0?05. In the group of Delaware Bay viruses, 34?5% of all nucleotide substitutions led to amino acid replacements. In the American lineage, 25?6% of nucleotide substitutions resulted in amino acid replacements, and in the Eurasian lineage, 20?4% of nucleotide substitutions resulted in amino acid replacements. Thus, although the Delaware Bay group falls between the Eurasian and the American viruses in the rate at which it acquires nucleotide substitutions, it has the highest percentage of nucleotide substitutions that result in amino acid changes. In the human H2 viruses having circulated in 1964?1968 (A/Korea/426/68, A/Izumi/5/65, A/Berlin/3/64, A/Berkeley/1/68), a comparable percentage (35?7%) of nucleotide substitutions led to amino acid changes. 

As shown previously, human influenza viruses evolve rapidly because of the pressure of the neutralizing antibodies of the host (Both et al., 1983 ). Avian species produce humoral and cell-mediated responses to influenza virus infection, but their antibody responses are short-lived (Kida et al., 1980 ); moreover, a large number of young susceptible birds are produced every year, eliminating the immune pressure among avian viruses. The high rate of HA evolution in Eurasian-type American H2 viruses suggests the existence of an unknown positive selection mechanism that favours amino acid changes in the transferred virus, probably connected with the transfer to the new environment. This finding is also at variance with our earlier findings of evolutionary stasis among influenza viruses in their natural reservoirs (Webster et al., 1992 ) and indicates that this may not apply to all aquatic birds. 
The higher percentage of amino acid replacements in the HA of the Delaware group of viruses may lead to changes in their antigenic reactivity pattern. To investigate this possibility, haemagglutination titrations and haemagglutination inhibition (HI) assays were performed as previously described (Rogers et al., 1983 ). Ascitic fluids from mice containing monoclonal antibodies (MAbs) to the HA of the H2 influenza subtype (Yamada et al., 1984 ) were used in the HI tests. The HA of avian viruses isolated in North America demonstrated two patterns of reactivity with the panel of MAbs (Table 2). However, the antigenic and phylogenetic groups did not coincide. The American viruses react with most MAbs in the panel. In contrast, the Delaware Bay (shorebird and gull) viruses reacted with only two or three MAbs. This pattern of reactivity, which had been reported earlier for one Delaware Bay shorebird strain (A/Herring gull/Delaware/677/88), extended to all of the four shorebird viruses characterized. However, the Delaware Bay strains are not unique in this respect. One Eurasian strain, A/Duck/GDR/72, and one American strain, A/Chicken/New York/29878/91, had shown a similar pattern of reaction (Schafer et al., 1993 ). 

<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>View this table:
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 </TD><TD vAlign=top align=left>Table 2. Haemagglutination inhibition by monoclonal antibodies
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The disparity between the antigenic and phylogenetic groupings suggests that most of the amino acid replacements have not been affecting antigenic specificity. However, the changes at position 137, 189 and 141?144 may be relevant to the antigenic variability of the H2 subtype. These substitutions are located in antigenic sites A and B as outlined for the 3D structure of H3 (Wiley et al., 1981 ). 

Several influenza A virus HA subtypes comprise geographically separate lineages (Garcia et al., 1997 ; Donis et al., 1989 ). These lineages may have emerged because of nonoverlapping migration routes. Most wild birds follow North?South migration routes that are separate for each hemisphere. Further, the birds that migrate across the Atlantic do so at times when North?South migrations are over. For example, the Canadian terns and gulls that cross the Atlantic (Curry-Lindahl, 1975 ) arrive in Europe after the European birds have migrated to Africa. On rare occasions, unusual weather conditions may bring the two populations into contact, allowing the interregional transmission of viruses. Turnstones, which are pelagic birds and whose migration is not fully resolved, may play a role in this transmission (Curry-Lindahl, 1975 ). However, such occasional transmissions would be unlikely to lead in each case to circulation of the transferred virus; otherwise, the phylogenetically distinct lineages would not have arisen. The circulation of Eurasian H2 virus in the Delaware shorebirds for at least 10 years does not necessarily suggest the existence of some specific, as yet unknown, conditions in the area that favour the virus: new Eurasian-type H2 viruses may be circulating in other parts of America as well. All of the sequenced H2 viruses isolated from gulls in other parts of America were isolated earlier than 1988. The first Delaware Eurasian-type virus was isolated in 1988. If the transfer occurred not long before 1988, it is possible that the Eurasian-type viruses are in fact not restricted to Delaware Bay but are instead restricted to shorebirds and gulls (Kawaoka et al., 1988 ). 
H2 virus is the only pandemic influenza virus subtype that has not circulated in the human population for the last 30 years. Therefore, the probability that H2 viruses will reappear in humans may be high. It is generally accepted that the 1957 and 1968 influenza pandemics were produced by reassortant human strains with HA genes that originated from avian influenza viruses. Although the details of the transfer of Eurasian H2 virus strains to North America are not yet clear, the existence of this transfer has important implications. The Eurasian avian influenza virus strains are those most closely related to human H2 viruses (Schafer et al., 1993 ) and are potential sources of genes for future pandemic influenza strains. These are compelling reasons for the further study and surveillance of avian H2 strains circulating in the Americas. 

<TABLE cellSpacing=0 cellPadding=0 width="100%" bgColor=#e1e1e1><TBODY><TR><TD vAlign=center align=left width="5%" bgColor=#ffffff></TD><TH vAlign=center align=left width="95%"> Acknowledgments </TH></TR></TBODY></TABLE>
The research described in this publication was made possible in part by award RN1-412 of the U. S. Civilian Research & Development Foundation for the Independent States of the Former Soviet Union (CRDF) and by Public Health Research Grant AI29680 and Cancer Centre Support (CORE) grant CA-21765 from the National Institutes of Health, and by the American Lebanese Syrian Associated Charities. We thank Sharon Naron for editorial assistance. 

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References
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**wetDirt** · December 19, 2007, 02:07 PM

Re: New swine flu has avian flu genes

The research team studied an unknown pathogen that in 2006 infected two groups of pigs at separate production facilities. Both groups of pigs used water obtained from ponds frequented by migrating waterfowl. Molecular studies indicated the unknown pathogen was an H2N3 influenza virus closely related to an H2N3 strain found in mallard ducks. However, this was the first time it had been observed in mammals.

This is interesting on several fronts. Interesting that in an industrialized country in 2006, swine at a production facility shared drinking water with wild ducks. Really? I thought that co-mingling of species, including humans, only happened in third-world countries.

Nobody ever observed a jump from birds to swine? Then they could hardly have been looking, there are lots of H1N1 sequences with regions of identity between birds, humans, and swine.

And finally, Iowa is on the Mississippi flyway. And there are speces that migrate between Asia and North America that don't stop in Alaska. This is not a reassuring article at all.

**HenryN** · December 19, 2007, 02:14 PM

Re: New swine flu has avian flu genes

Originally posted by wetDirt View Post

This is interesting on several fronts. Interesting that in an industrialized country in 2006, swine at a production facility shared drinking water with wild ducks. Really? I thought that co-mingling of species, including humans, only happened in third-world countries.

Nobody ever observed a jump from birds to swine? Then they could hardly have been looking, there are lots of H1N1 sequences with regions of identity between birds, humans, and swine.

And finally, Iowa is on the Mississippi flyway. And there are speces that migrate between Asia and North America that don't stop in Alaska. This is not a reassuring article at all.

There is a lot of recombination between swine and avian sequences (especially H5N1 and H9N2).

**HenryN** · December 19, 2007, 02:27 PM

Re: New swine flu has avian flu genes

ARS: New swine flu has avian flu genes
Dec. 19, 2007

Researchers have identified a new strain of swine influenza -- H2N3 -- which belongs to the group of H2 influenza viruses that last infected humans during the 1957 pandemic. This new strain has a molecular twist: It is composed of avian and swine influenza genes.

Agricultural Research Service (ARS) veterinarians Juergen Richt, Amy Vincent, Kelly Lager and Phillip Gauger conducted this research with Iowa State University (ISU) visiting scientist Wenjun Ma, ISU veterinarian Bruce Janke and other colleagues at the University of Minnesota and St. Jude Children's Research Hospital. The ARS veterinarians work at the agency's National Animal Disease Center in Ames, Iowa.

The research team studied an unknown pathogen that in 2006 infected two groups of pigs at separate production facilities. Both groups of pigs used water obtained from ponds frequented by migrating waterfowl.

Molecular studies indicated the unknown pathogen was an H2N3 influenza virus that is closely related to an H2N3 strain found in mallard ducks. But this was the first time it had been observed in mammals.

Influenza viruses have eight gene segments, all of which can be swapped between different virus strains. Two of these gene segments code for virus surface proteins that help determine whether an influenza virus is able to infect a specific host and start replicating -- the first step in the onset of influenza infection.

In the newly isolated swine H2N3, the avian H2 and N3 gene segments mixed with gene segments from common swine influenza viruses. This exchange -- and additional mutations -- gave the H2N3 viruses the ability to infect swine. Lab tests confirmed that this strain of H2N3 could also infect mice and ferrets.

These findings provide further evidence that swine have the potential to serve as a "mixing vessel" for influenza viruses carried by birds, pigs and humans. It also supports the need to continue monitoring swine -- and livestock workers -- for H2-subtype viruses and other influenza strains that might someday threaten swine and human health.

Results of this study were published online this week in the Proceedings of the National Academy of Sciences of the United States of America.

SOURCE: USDA news release.

http://www.agprofessional.com/show_story.php?id=50087

**wetDirt** · December 19, 2007, 02:32 PM

Re: New swine flu has avian flu genes

Originally posted by niman View Post

There is a lot of recombination between swine and avian sequences (especially H5N1 and H9N2).

That's what I thought. Is there some consistent preference in mixing by strain? Does it depend more on random chance and abundance, or do certain strains combine "better" than others because of structural similarities? Does the extent depend on the initial degree of similiarity between strains?

**HenryN** · December 19, 2007, 04:54 PM

Re: New swine flu has avian flu genes

INFLUENZA A (H2N3) VIRUS, SWINE - USA
*************************************
A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases
<http://www.isid.org>

Date: 17-18 Dec 2007
Source: Proc Natl Acad Science USA Early Edition [edited]
<http://www.pnas.org/cgi/content/abstract/0710286104v1?etoc>

[Below is the abstract of a paper in the online edition of the Proceedings
of the National Academy of Sciences of the USA (PNAS), which describes the
characterization of an influenza virus with potential to become the
precursor of a human pandemic virus.]

Identification of H2N3 influenza A viruses from swine in the United States
--------------------------------------------------------------------------
By Wenjun Ma, Amy L Vincent, Marie R Gramer, Christy B Brockwell, Kelly M
Lager, Bruce H Janke, et al. At the Department of Veterinary Diagnostic and
Production Animal Medicine, College of Veterinary Medicine, Iowa State
University, Ames, IA 50011; Virus and Prion Diseases of Livestock Research
Unit, National Animal Disease Center, Agricultural Research Service, United
States Department of Agriculture, Ames, IA 50010; Veterinary Diagnostic
Laboratory, College of Veterinary Medicine, University of Minnesota, St.
Paul, MN 55108; St. Jude Children's Research Hospital, Memphis, TN 38018;
and Interdisciplinary Program, University of Tennessee Health Science
Center, Memphis, TN 38163

Abstract
--------
Although viruses of each of the 16 influenza A HA subtypes are potential
human pathogens, only viruses of the H1, H2, and H3 subtype are known to
have been successfully established in humans. H2 influenza viruses have
been absent from human circulation since 1968, and as such they pose a
substantial human pandemic risk. In this report, we isolate and
characterize genetically similar avian/swine virus reassortant H2N3
influenza A viruses isolated from diseased swine from 2 farms in the United
States. These viruses contained leucine at position 226 of the H2 protein,
which has been associated with increased binding affinity to the mammalian
alpha-2,6Gal-linked sialic acid virus receptor. Correspondingly, the H2N3
viruses were able to cause disease in experimentally infected swine and
mice without prior adaptation. In addition, the swine H2N3 virus was
infectious and highly transmissible in swine and ferrets. Taken together,
these findings suggest that the H2N3 virus has undergone some adaptation to
the mammalian host and that their spread should be very closely monitored.

--
communicated by:
ProMED-mail <promed@promedmail.org>

[The current concentration of attention on the potential of avian influenza
A/H5N1 virus to evolve into a human pandemic pathogen should not divert
attention from the presence in the environment of other potential
precursors of influenza viruses with equal or perhaps greater potential to
become human pandemic pathogens. - Mod.CP]

[see also:
Avian influenza, human (113): pandemic prediction 20070726.2410
2005
---
Influenza virus, 1918 pandemic strain: reconstruction (02) 20051006.2919
Avian influenza, human - East Asia (111): pandemic preparedness 20050804.2264]

.................cp/msp/sh

**HenryN** · December 20, 2007, 09:05 AM

Re: New swine flu has avian flu genes

Commentary at

Swine H2N3

http://www.recombinomics.com/News/12200702/H2N3_Swine.html

Recombinomics Commentary

**Niko** · December 20, 2007, 09:15 AM

Re: New swine flu has avian flu genes

Does anyone know if the flu was ever typed for these two cases from August:

Page not found – Morning Journal

http://www.morningjournal.com/site/printerFriendly.cfm?brd=1699&dept_id=46371&newsid=18723075

<table border="0" cellpadding="2" cellspacing="0" width="100%"><tbody><tr><td style="font-weight: bold; font-size: 12px; font-family: serif;">08/18/2007</td></tr><tr><td style="font-weight: bold; font-size: 19px; font-family: serif;"> Cases of flu hit Huron County Fair </td></tr><tr><td style="font-weight: bold; font-size: 12px; font-family: serif;"> Morning Journal Staff </td></tr></tbody></table>
NORWALK -- There has been two confirmed cases of flu at the Huron County Fair that health officials are investigating to see if it was transmitted from pigs to humans.
The influenza A cases were confirmed, through rapid screening, in a fair exhibitor and the exhibitor's father, according to the Huron County General Health District. There has also been reports of flu-like symptoms in pigs at the county fairgrounds.

''At this point, no connection has been medically established between the swine and human cases,'' said Tim Hollinger, administrator of the Huron County General Health District.

No testing has been done yet to confirm what is causing the illness in the pigs, he said. Further testing will be done by the Ohio Department of Agriculture and the Ohio Department of Health to see if the two human cases can be matched to the illness in the pigs, according to the health department.

Fair veterinarians believe the pigs are past the contagious period, but the Huron County Fair Board has decided to close the pig barns to the public. Today, is the last day of the fair.

Type A influenza can be transmitted from pigs to humans, but it is rare. There had only been rare documented cases of human-to-human transmission of flu that originated from swine, according the health district.

**JJackson** · December 20, 2007, 09:28 AM

Re: New swine flu has avian flu genes

The articles do not make it clear if these were free-range with access to the pond (snout in the bird droppings - high viral load) or the water was being piped from the ponds to housed pigs. If anyone has seen this information please post. Thanks.

**HenryN** · December 20, 2007, 11:59 AM

Re: New swine flu has avian flu genes

Originally posted by Niko View Post

Does anyone know if the flu was ever typed for these two cases from August:

Page not found – Morning Journal

http://www.morningjournal.com/site/printerFriendly.cfm?brd=1699&dept_id=46371&newsid=18723075

<TABLE cellSpacing=0 cellPadding=2 width="100%" border=0><TBODY><TR><TD style="FONT-WEIGHT: bold; FONT-SIZE: 12px; FONT-FAMILY: serif">08/18/2007</TD></TR><TR><TD style="FONT-WEIGHT: bold; FONT-SIZE: 19px; FONT-FAMILY: serif">Cases of flu hit Huron County Fair </TD></TR><TR><TD style="FONT-WEIGHT: bold; FONT-SIZE: 12px; FONT-FAMILY: serif">Morning Journal Staff </TD></TR></TBODY></TABLE>
NORWALK -- There has been two confirmed cases of flu at the Huron County Fair that health officials are investigating to see if it was transmitted from pigs to humans.
The influenza A cases were confirmed, through rapid screening, in a fair exhibitor and the exhibitor's father, according to the Huron County General Health District. There has also been reports of flu-like symptoms in pigs at the county fairgrounds.

''At this point, no connection has been medically established between the swine and human cases,'' said Tim Hollinger, administrator of the Huron County General Health District.

No testing has been done yet to confirm what is causing the illness in the pigs, he said. Further testing will be done by the Ohio Department of Agriculture and the Ohio Department of Health to see if the two human cases can be matched to the illness in the pigs, according to the health department.

Fair veterinarians believe the pigs are past the contagious period, but the Huron County Fair Board has decided to close the pig barns to the public. Today, is the last day of the fair.

Type A influenza can be transmitted from pigs to humans, but it is rare. There had only been rare documented cases of human-to-human transmission of flu that originated from swine, according the health district.

In mIchigan it was H1N2. For the two in Ohio, the CDC didn't say

Three human cases of novel influenza A infection were reported from two states (Ohio (2) and Illinois (1)) in September. All three persons were infected with swine influenza A virus. Although human infection with swine influenza is uncommon, sporadic cases occur in many years, usually among persons in direct contact with ill pigs or who have been in places where pigs might have been present (e.g. agricultural fairs, farms, or petting zoos). The sporadic cases identified in recent years have not resulted in sustained human-to-human transmission or community outbreaks.