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AVIAN INFLUENZA & NEWCASTLE DISEASE ACTIVITIES
M I A K I M T O R C H E T T I , D V M M S P H D
S E C T I O N H E A D - AV I A N , D I A G N O S T I C V I R O LO G Y L A B O R ATO R YU . S . D E PA R T M E N T O F A G R I C U LT U R EA N I M A L A N D P L A N T H E A LT H I N S P E C T I O N S E R V I C EV E T E R I N A R Y S E R V I C E S
O C TO B E R 2 0 1 7
Part I – Year in Review◦ H5/H7 status
◦ Test protocol and reporting
Part II – Update◦ IAV and APMV-1 activity
◦ Test workflow
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Overview
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Historic global HPAI reports by subtype/year 1934-2017 (n=419; count by subtype and country)
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Predominated by gsGD H5
• HPAI reported at low frequency• Aquatic migratory birds found
to be natural hosts of low pathogenic strains
• HPAI not observed in natural hosts
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H5 H5 gsGD
H5 HPAI BY REGION N=375
Africa Americas Asia Australia Europe
What do we know about the genesis of HPAIV from LPAIV?
E R I C A S PA C K M A N , M A R Y PA N T I N - J A C K W O O D , D A V I D
S W AY N E , D A V I D S U A R E Z , D A R R E L K A P C Z Y N S K I
U S N AT I O N A L P O U LT R Y R E S E A R C H C E N T E R
U S D A - A R S , AT H E N S , G A
COURTESY OF E. SPACKMAN, ET AL, USDA NPRC, ATHENS, GA
Technically only applies to gallinaceous poultry
Highly pathogenic (HP) has always been an H5 or H7 subtype◦ Other subtypes?
◦ Some H4, H6 and H10 isolates (Brugh and Beck 1992; Capua et al.; Swayne et al. 1994; Wood et al. 1996) met the definition based on a IV lethality study, but not by a natural route of exposure
◦ LPAIV can also cause disease, low rates of mortality, and decreases in production
COURTESY OF E. SPACKMAN, ET AL, USDA NPRC, ATHENS, GA
First, what do we mean by highly pathogenic and low pathogenic?
Highly pathogenic: Systemic infection
Low pathogenic: Localized infection
What determines if the infection will become systemic?
– A very short protein sequence in the HA protein → the proteolytic cleavage site (PCS) – as defined for chickens
Chen, et al., Cell 95
(409-17). 1998
COURTESY OF E. SPACKMAN, ET AL, USDA NPRC, ATHENS, GA
The HA protein must be cut by an enzyme in the host cell so that the virus can replicate.
COURTESY OF E. SPACKMAN, ET AL, USDA NPRC, ATHENS, GA
Where cleavage occurs by enzymes only in the respiratory tract or intestinal tract = LPAI
Where cleavage occurs by enzymes available in many tissues = HPAI
HPAIVLPAIV
H5 or H7
The mutation from LPAIV to HPAIV occurs when LPAIV
circulates in chickens and turkeys
Selection pressure
Why does LPAIV mutate to HPAIV in chickens and turkeys?
COURTESY OF E. SPACKMAN, ET AL, USDA NPRC, ATHENS, GA
LPAIVH5 or H7
HPAIV
Can we predict which viruses will mutate?
COURTESY OF E. SPACKMAN, ET AL, USDA NPRC, ATHENS, GA
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The most sensitive and specific tools target conserved regions of the influenza Type A (IAV) protein or genome (e.g. matrix, nucleoprotein).
The virus pathotype is ‘presumptive’ based upon the clinical presentation of the flock compared to the USDA HPAI case definition and ‘confirmed’ based upon the HA cleavage site sequence.
What do the other tests tell us?
Diagnostic considerations
Target HA subtype NA subtype pathotype
IAV AGID/ELISA NP-Antibody W W W
IAV HI/NI HA-Antibody ✓ ✓ W
IAV-M PCR M-RNA W W W
H5/H7 PCR HA-RNA ✓ W W
Sequencing genome ✓ ✓ ✓
In vivo pathogenicty test in vivo W W ✓
✓ = test can determine
W = test cannot determine
NPIP AGID/ELISA
• Detect antibody to NP
NVSL HI
• H1-H16
• Confirm antibody to HA
NVSL NI
• N1-N9
• Confirm antibody to NA
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Serologic Test ProtocolEstablishes prior exposure
Test cannot determine pathotypeTest cannot determine virus status
How is the finding confirmed?
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Molecular Test Protocol
Establishes virus statusPCR cannot determine pathotype
Requires sequence or in vivo testing
NAHLN lab rRT-PCR
•FluA (M)
•Subtype (H)
NVSL rRT-PCR
•FluA (M)
•Subtype (H)
NVSL Sequence
•Pan HA (H)
•Pan NA (N)
•Full genome
NVSL Virus Isolation
• In vivo test
•Gen/ant.char
How is the finding confirmed?
How Test Results Contribute to Flock Status*
*Avian influenza-affected flock based upon non-negative antigen results or antibody detection at a NAHLN or NPIP lab.
Subtype: H5 or H7
Clinical presentation
NAHLN lab
NVSL
Presumptive by rRT-PCR
Cannot determine
Confirmed by molecular test orserology (HI/NI)
Pathotype: Low or highly
pathogenic
Clinical presentation
NAHLN/NPIP lab
NVSL
Presumptive (see case definition)
Test cannot determine
Confirmed by virus sequence and/or in vivo testing
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Reporting…simplified
Test confirmed SectorInternational
Reporting
HPAI or LPAI as confirmed by virus sequence
&/or isolation
HPAI – any LPAI – all except
BYDImmediate
H5/H7 PCR +/- antibody,no virus or sequence+ follow-up negative
Commercial Immediate
LBM and BYD6-month
+ bilateral trading partners
H5/H7 Antibody only, no PCR, virus or sequence
+ follow-up negativeAll
Only bilateral trading partners
2016-17 Poultry Events
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Date State Surv stream
Subtype
(AM=North American) Outcome
Jan-16 IN Commercial turkeysHPAI/LPAI H7N8, first H7N8
HPAI detection
Limited spread, mutation to
HPAI occurred at a single site
Apr-16 MO Commercial turkeys LPAI H5N1 Single premises with
no further spread
Jun-16 NJ, NY, PALBM - primarily
MuscovysLPAI H5N2
Traced to single
distributor/source flock
Mar-17 TN, AL, KY, GACommercial chickens
and backyards
LPAI AM H7N9
HPAI in TN only
Multiple point source LPAI
introductions; HPAI mutation
occurred at a single location
with lateral spread to one site
Mar-17 WI Commercial turkeys LPAI H5N2
Single premises with
no further spread; unrelated to
H5N2 from LBM
Apr-17 ID Backyard duck LPAI H5N2
Single premises with
no further spread;
unrelated to other recent H5N2
• Turkeys in Indiana – initial detection in response to clinical signs.
• LPAI>HPAI mutation occurred in a single flock.
• Data from a highly similar wild bird virus collected in KY 11/2015 (6/8 genes) allows estimate for both the timing and likely location of introduction, and is supported by epidemiologic data.
2016 January: AM H7N8
Virology, Volume 507, July 2017, Pages 216-219Dong-Hun Lee, Mia Kim Torchetti, Mary Lea Killian, David E. Swayne
2017 March: AM H7N9• Commercial chickens and backyard
flocks – initial detection in response to clinical signs.
• LPAI>HPAI mutation occurred once (later during circulation) with a single event of secondary spread.
• Data from a highly similar wild bird virus collected in WY 9/2016 (8/8 genes) allows estimate for timing andfrequency of introductions, and is supported by epidemiologic data.
• More than one independent introduction.
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HPAI
USDA-APHIS (2017). Epidemiologic and other analyses of avian influenza: April 27, 2017 Report. USDA:APHIS:VS:STAS:Center for
Epidemiology and Animal Health. Fort Collins, CO. April 2017. Doc #391.0317.
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H2N2 in Northeast LBMS since 2014LBM H2N2 2015 2016 2017
CT 3 4 8
MA 0 1 0
NJ 7 13 6
NY 8 5 80
PA 3 0 21
RI 0 1 0
H7N2 in Cats at NYC Shelter
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