Transcript Slide 1

Tanja Opriessnig
The Roslin Institute, University of Edinburgh, UK
Veterinary Diagnostic and Production Animal Medicine
Iowa State University, USA
PEDV
Background
PRDC
• Discovered in 1971 in the UK
– Acute outbreaks of diarrhea in feeder pigs and fattening pigs
– Suckling pigs did not become sick
– Oldham et al., 1972
• Family Coronaviridae
– Enveloped, positive stranded RNA viruses
– Subfamilies: Coronavirinae & Torovirinae
– Important for pigs:
• Genus Alphacoronavirus
– PEDV, TGEV: Diarrhea
– PRCV: Respiratory disease
• Genus Betacoronavirus
– Porcine haemaggluination encrophalomyelitis virus (HEV): Encephalomyelitis
• Genus Deltacoronavirus
– Porcine deltacoronavirus (PDCV): Diarrhea (?)
Background
PEDV
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3397359
Spike
PRDC
Nucleocapsid
• Structure:
Envelope protein E
– Nucleocapsid (N) protein
• Highly conserved: Best for testing
– Spike (S) protein
– Integral membrane (M) protein
– Small envelope (E) protein
Membrane protein M
Age
group
PEDV
Diarrhea
Mortality
Suckling pigs
++++
100% in
naïve
populations
Nursery pigs
+++
++
Grow-finish pigs
++
-
Adults
+
-
PRDC
PEDV Shedding
PEDV
PRDC
Fecal shedding:
• Up to at least 2835 + days post
infection
(neonatal and
nursery pigs)
• Large amounts
• Possible contribution factors:
–
–
–
–
Age dependency
Differences in virulence between isolates?
Cross-protection between strains?
Interaction with other pathogens?
Viremia:
• Short (days)
• Low amounts
PEDV
Global Importance
PRDC
USA:
PEDV still spreading
Europe:
Epidemics until the
late 80ies; Reports
after 2000 are rare
1971
2013
1982
1993
China:
Severe epidemics
in recent years
• Only infectious for pigs
– No role in public health
PEDV
USA Discovery Timeline
PRDC
MON
TUE
WED
THU
FRI
SAT
SUN
April 15
April 16
April 17
April 18
April 19
April 20
April 21
April 22
April 23
April 24
April 25
April 26
April 27
April 28
April 29
April 30
May 1
May 2
May 3
May 4
May 5
Diarrhea
IA
Diarrhea
IA
May 6
May 7
May 8
May 9
May 10
May 11
May 12
EM-CoV
Diarrhea
CO
Pan-CoV
PCR +
May 18
May 18
Diarrhea
IA
Diarrhea
IA
May 13
Diarrhea
IN
May 14
NVSL
Sequencing
Source: ISU-VDL 2013
May 15
May 16
May 17
Sequencing
PEDV China
NVSL
confirms
USDA
announces
PEDV
U.S. Pig Inventory 2007
PRDC
Density Level
http://www.factoryfarmmap.org/#animal:hogs;location:US;year:2007
PEDV
April 2013
PRDC
IA
IN
Introduction of PEDV into the USA
OH
TIMELINE
PEDV
May 2013
PRDC
MN
SD
MI
IA
IL
CO
IN
OH
PA
MO
OK
Introduction of PEDV into the USA
TIMELINE
PEDV
June 2013
PRDC
MN
SD
MI
NY
IA
CO
IL
KS
PA
MO
OK
Introduction of PEDV into the USA
IN
OH
NC
TIMELINE
PEDV
July 2013
PRDC
MN
SD
WI
MI
NY
IA
IL
CO
IN
OH
PA
MO
KS
OK
TN
NC
TX
Introduction of PEDV into the USA
TIMELINE
PEDV
October 2013
PRDC
MN
SD
WI
MI
NY
IA
IL
CO
IN
MO
KS
OH
PA
MD
KY
OK
TN
NC
TX
Introduction of PEDV into the USA
TIMELINE
PEDV
December 2013
PRDC
MN
SD
WI
MI
WY
NY
IA
NE
IL
CO
CA
IN
MO
KS
OH
PA
MD
KY
OK
TN
NC
TX
Introduction of PEDV into the USA
TIMELINE
PEDV
January 2014
PRDC
MN
SD
WI
WY
MI
NY
IA
NE
IL
CO
IN
OH
MD
MO
KS
PA
KY
CA
OK
AZ
TN
NC
SC
TX
Introduction of PEDV into the USA
TIMELINE
PEDV
February 2014
PRDC
ND
MT
MN
SD
ID
WI
WY
MI
NY
IA
NE
IL
CO
IN
OH
MD
MO
KS
PA
KY
CA
OK
TN
SC
AZ
NC
TX
Introduction of PEDV into the USA
TIMELINE
PEDV
March 2013
PRDC
ND
MT
MN
ID
SD
WY
VT
WI
MI
NE
NY
IA
IL
CO
IN
OH
MD
MO
KS
PA
KY
CA
OK
TN
NC
SC
AZ
MS
TX
Introduction of PEDV into the USA
TIMELINE
PEDV
Distribution of PEDV in the U.S
PRDC
Source: AASV
PEDV
Total Number of Positive Pig Samples
PRDC
15-Jun-13 to 8-May-14:
Age group
No.
Suckling
1,366/2,343 (49.3%)
Nursery
1,183/2,817 (36.8%)
Grow/finisher
1,199/3,123 (28.3%)
Sows/Boars
558/1,380 (28.6%)
TOTAL
4,306/9,663 (44.6%)
29 (30) States are affected to date
Image Source: ISU-VDL 2013
PEDV
2013 Genotyping
PRDC
Emerging
PEDVs in Asia
and the US
Historical PEDVs in
Europe and Asia
Source: Huang Y et al. mBio 2013; doi 10.1128/mBio.00737-13
PEDV
Origin of the U.S. PEDV strains
PRDC
Source: Huang Y et al. mBio 2013; doi 10.1128/mBio.00737-13
PEDV
Evidence of 2nd PEDV Introduction
2014
PRDC
Whole genome
sequencing
Spike
protein
sequencing
Source: Wang et al. Emerging Infectious Disease 2014; No. 5, May 2014
Diagnostics
PEDV
PRDC
• Diagnostic Specimens
– Intestines (Fresh)
– Feces
– Oral fluids
– Intestines (Fixed)
– Serum
Virus isolation
Real-time RT-PCR
Electron microscopy
Immunohistochemistry
Indirect Fluorescent Antibody, ELISA
Sequencing
PEDV
Total Number of Positive Pig Samples
Weekly Basis
PRDC
Source: AASV
PEDV
PRDC
Cumulative Number of Positive
Samples
7000
6000
5000
4000
3000
2000
1000
0
Source: AASV
6,421
PEDV Economic Impact
PEDV
PRDC
• Approximately 5 million pigs have died in
the U.S.
– About 4.5% of the animals sent to processing
plants last year in the U.S
– Source: AgriTrends
• It is estimated 12.5 million fewer pigs will
be slaughtered in 2014, which will result in
an overall U.S. pork production decline of
6-7%
– Largest estimated decrease in 30 years
– Source: Rabobank
PEDV
Economic Impact of PEDV
•PRDC
Estimated shortfall in market hogs from PEDV
to North American slaughters
0%
• ((Source: Rabobank)
Canada
US
-5%
Mexico
-10%
-15%
-20%
-25%
Dec 13
Mar 14
Jun 14
Sep 14
Dec 14
Mar 15
Jun 15
Sep 15 Dec 15
Porcine Deltacoronavirus (PDCV)
PEDV
PDCV
PRDC
• Initially discovered in Hong Kong in
2009 (Woo et al., 2012)
• Described in the U.S. in 2014
– Associated with diarrhea in sows and
their litters
– No experimental data to date
– Precise pathogenesis and role of PDCV
is currently unknown
PEDV
PDCV
Distribution of PDCV in the U.S.
PRDC
Source: AASV
PEDV
PRDC
PEDV versus PDCV
Cumulative US results
Positive Accessions
Total Accessions tested
PEDV
6,421
17,468
PDCV
142
1,091
%
Positive States
36.8%
29 (30)
13.0%
14
PEDV
PEDV Transmission
What is known so far
PRDC
• Rapidly spread across U.S.
– Transport vehicles
• PEDV negative trucks returning from
abattoirs positive (Lowe et al., 2014)
– Animal movement
– Aerosol transmission?
Source: Dr. Darin Madson
PEDV Transmission
PEDV
Role of Feed
PRDC
• Detection of PEDV RNA in feed
– Confirmation of PEDV RNA in porcine plasma derived
products
– Relationship with PEDV outbreaks in Canada?
• Recall of pelleted nursery feeds containing plasma
ingredients in Ontario
– CFIA (18-Feb-14); Feedstuffs (20-Feb-14)
– 4-Mar-14: CFIA could not confirm live virus in feed pellets
containing blood plasma
• Ban of spray-dried porcine plasma products in the UK (Vet
Rec, May 2014)
• Centre de développement due pork du Québec Inc (CDPQ)
risk analysis
– Feed is medium risk for PEDV transmission
– Study by Scott Dee, Pipestone Applied Research
PEDV
2014 ISU Experiment
PRDC
Group
Designation
No. of
pigs
Diet
Inoculation
NEG-CONTROL
SDPP-CONTROL
8
8
No SDPP
5% SDPP
Dpi 0
PBS
PBS
PEDV-CONTROL
8
No SDPP
PEDV
Viremia only in PEDV-CONTROL group
Seroconversion only in PEDV-CONTROL group
Conclusion:
No evidence of infectivity of the PEDV present in the investigated plasma lot
Summary
PEDV
PRDC
• PEDV is now prevalent in the majority of swine
producing states in the USA
• Epidemic situation
Endemic situation?
• Lesion learned: Constant awareness
– Globalization increases the risk of pathogen
introductions
– Need to invest in rapid epidemiological studies to
document how PEDV was introduced to the US and
learn from this situation
– Need much more work on advancing understanding
of transmission routes
• Pigs, people, trucks, fomites, feed, air, water etc…
STOP
PEDV