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Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Swine Influenza – Host Range and Zoonotic Considerations.

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Presentation on theme: "Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Swine Influenza – Host Range and Zoonotic Considerations."— Presentation transcript:

1 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Swine Influenza – Host Range and Zoonotic Considerations R.B. Baker, DVM, MS Senior Clinician ISU Swine Section VDPAM 445

2 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Swine Influenza A (H1N1) Infection in Two Children — Southern California, March– April 2009 On April 17, 2009, CDC determined that two cases of febrile respiratory illness occurring in children who resided in adjacent counties in southern California were caused by infection with a swine influenza A (H1N1) virus. The viruses from

3 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University

4 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Swine Influenza (SI)  Acute and highly infectious single strand RNA viral disease of pigs and many other species  SI is a type A influenza in the family Orthomyxoviridae

5 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University

6 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State UniversityInfluenzaInfluenza Swine - (A)Swine - (A) Many Avian species – waterfowl (A)Many Avian species – waterfowl (A) Canines – (B)Canines – (B) Felids - Exotics and domestic (A)Felids - Exotics and domestic (A) Equine – (B)Equine – (B) Primates – Homo sapiens (A,B)Primates – Homo sapiens (A,B) Marine Mammals (A)Marine Mammals (A)

7 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Influenza Enveloped VirusEnveloped Virus Single strand, Negative sense RNA genomeSingle strand, Negative sense RNA genome Eight ORF – SegmentedEight ORF – Segmented Code for 10 (11) viral proteinsCode for 10 (11) viral proteins  HA – Hemagglutinin }  NA - Neuraminidase }  M - Matrix  NP - nucleoprotein  NS – nonstructural protein  PB1 - polymerase B1  PB2 – Polymerase B2  PA – Polymerase A

8 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State UniversityInfluenzaInfluenza HA and NA are imbedded in the envelopeHA and NA are imbedded in the envelope The major surface glycoprotein'sThe major surface glycoprotein's –Virulence –Immunity –Diagnostics

9 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State UniversityInfluenzaInfluenza HAHA –attaches to the host receptor NANA –Releases new virus from infected cells M2M2 –Uncoating and release of viral genetic material PA, PB1, PB2PA, PB1, PB2 –Virus replication

10 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University (Hinshaw et al Can. J. Microbiol. 26: ; Webster et al Virology 84: ) (V.S. Hinshaw) “SUBTYPE SOUP” N1 N2 N3 N4 N5 N6 N7 N8 N9 H1 H2 H3 H4 H5 H6 H7 H8 H9 H10 H11 H12 H13 H14 H15H16 Yoon

11 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Influenza Evolution Antigenic Drift: –Point mutations due to polymerase errors Minor antigenic changes over time Antigenic Shift: –Reassortment occurring when one cell is infected by two viruses, allowing for shuffling of the segmented genome Major antigenic changes Both can lead to immune evasion

12 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University SI Divergence  Three swine sub-types of H3N2 in US  Several swine H1N2 re-assortments  Numerous swine H1N1 drift and shift strains  15 H and 9 N possibilities  High and low Path in Poultry

13 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Host Specificity HA binds to sialic acid linked to galactose as its receptor –Human viruses prefer α-2,6 linkage on respiratory epithelium –Avian viruses prefer α-2,3 linkage on G.I. epithelium –Pig respiratory epithelium express both receptor linkages “Mixing vessel” for avian-human reassortant viruses with pandemic potential Human and quail also shown to express both receptor linkages

14 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Influenza A Avian and Swine Influenza A virusesAvian and Swine Influenza A viruses –Avian viruses infect humans but rarely human to human transmission to date –Why are we concerned about HP- H5N1? –Are we close to another Pandemic? Probably not from the H5N1 virusesProbably not from the H5N1 viruses

15 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Influenza Pandemics Spanish flu (H1N1) - world wide Asian flu (H2N2) - US Hong Kong flu (H3N2) – US Swine flu scare (Fort Dix, US) 1977 Russian flu scare 1997 Avian flu scare (H5N1, H9N2) (Smithsonian, January 1989) Slide complements of KJ Yoon

16 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Recycling of H1, H2, and H3 Subtypes Hilleman Vaccine 20: Slide Complements of Amy Vincent

17 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Influenza A –However, The stage is set: Significant global movement of peopleSignificant global movement of people Significant H5N1 activity in wild birds, domestic birdsSignificant H5N1 activity in wild birds, domestic birds Significant illegal and legal bird trade in AsiaSignificant illegal and legal bird trade in Asia Spread from East and Central Asian to Mediterranean/African and other domestic birdsSpread from East and Central Asian to Mediterranean/African and other domestic birds > 250 human mortalities globally> 250 human mortalities globally Multi-species involvement – virus appears species promiscuousMulti-species involvement – virus appears species promiscuous Disruption of global eco-systemsDisruption of global eco-systems –It all looks bleak?

18 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Influenza - (H5N1 & others) Slide complements of KJ Yoon

19 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University

20 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Zoonosis and SE Asia

21 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University THE “BIRD FLU” - ASIA, (AP, Kuwana) (Reuters, Sukplang) (AFP) (AP, Kambayashi) (Reuters, Stringer) Yoon

22 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University

23 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University High Path in Chickens

24 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Crested Eagles intercepted in Belgium with Thai-Viet H5N1 High Path

25 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Global Water Fowl Flyways

26 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University *Investigation of morbidity and mortality events *Surveillance of live wild birds *Surveillance of hunter-killed birds *Surveillance of sentinel species *Environmental sampling. 116,000 samples ,000 samples

27 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Avian Influenza Serological surveillanceSerological surveillance –Commercial Poultry (NPIP) poultry flocks (meat & layers)poultry flocks (meat & layers) Agent surveillance (targeted surveillance) – PCR basedAgent surveillance (targeted surveillance) – PCR based –Wildlife (USDA APHIS WS) migratory water fowls (geese, ducks, gulls)migratory water fowls (geese, ducks, gulls) pharynx or cloacal swabpharynx or cloacal swab –Backyard Poultry (IDALS) to expand surveillance efforts (AI and END) in poultryto expand surveillance efforts (AI and END) in poultry –Upland Gamebirds (Iowa Poultry Assoc, USDA APHIS VS) Dead bird surveillance – oropharyngeal and cloacal swabDead bird surveillance – oropharyngeal and cloacal swab Live bird surveillance – cloacal swabsLive bird surveillance – cloacal swabs U of GA Photo

28 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Testing Summary (2006) Wild birds – 418 –19 pool positive (M and/or H5) Positive species: Teal (AGWT), MALL, Wigeon (AMWI), Pintail (NOPI) County: Tama, Johnson, Emmet, Sac, Worth, Winnebago, Jackson, Louisa, Polk, Marion, Greene, Lucas Subtype of AIV found: H5N2 (LPAI), H6N1 and H6N5 (LPAI), H3N2, H4N6 Backyard poultry – 77 –5 positive (no H5 or H7) Gamebirds – 1 –All negative

29 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University History of SI - US  SI is now believed to be an outcome of the 1918 global pandemic  Prior to 1918 had not been reported in pigs  Remained very stable for 75 years  The US appears to be ~unique  Resurrection of the 1918 virus (2005)  This is a classic Zoonosis – bird to human – (to the pig?)

30 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Swine Influenza in North America 1930 Slide Complements of Amy Vincent

31 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Circulating SIV In North America H3N2 cH1N1 rH1N1 H1N2 huH1N1 huH1N2 Triple reassortant internal gene (TRIG) cassette Slide Complements of Amy Vincent

32 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University SI – Pathogenesis/lesions  Tropism for bronchial epithelium  Incubation very short < 24hrs.  Cranioventral to patchy diffuse pneumonia  Interlobular edema  Fibrinous exudate in bronchi  Sequelae is bacterial pneumonia and gastric ulcers

33 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Influenza Virus

34 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Swine Influenza

35 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Swine Influenza (SI)  Nomenclature  Type (A)  Host (swine - Sw)  Place first isolated  Strain # if there is one  Year of first isolation  Antigenic subtype  A/Sw/MN/02-Novel H1N1 w/avian internals

36 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University SI - Epidemiology  People to Pigs / waterfowl to pigs  Waterfowl to domestic birds to humans  In parts of Asia people, ducks, chickens, pigs, & wild animals/birds live together  In the US is water supply is important?  Cross protection between strains?  HI tests are misleading  Virus isolation and sequencing

37 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University H1 and H3 NC Swine SI Isolates H1N2-like and H1N2-VAX group Novel H1N1- like group and H1N1- like VAX group H3N2 group

38 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Iowa Swine Isolates

39 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University What’s Next? H5N1? H4N6 H2N3 Photo courtesy of Alex Ramirez

40 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University 2 “Untypable” SIV isolates Dr. Marie Gramer at MN-VDL –April 2006 and Sept farms with respiratory disease outbreaks in growing pigs (~5-12 weeks of age) –Isolates were not typable using SIV specific assays Virus isolation positive on MDCK cells and by NP RT-PCR Non-reactive with reference sera HA and/or NA RT-PCR negative

41 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University Case Histories 2 Missouri farms with different owners Multiple sow farms fed pigs into both sites 4 miles apart Did not share: –Pigs –Feed –Personnel –Trucks Both used surface pond water for drinking and cleaning Slide Complements of Amy Vincent

42 Food Supply Veterinary Services Veterinary Diagnostic and Production Animal Medicine Iowa State University 2007 County Fair Pigs and people sick Identical virus in pigs and people Pig virus highly virulent and transmissible in the NADC experimental model Nearly identical virus (whole genome) identified in Kansas finishing pigs 4 mos later ? Slide Complements of Amy Vincent


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