Dr. Darin Madson - Porcine Epidemic Diarrhea Virus Update

Veterinary Diagnostic LaboratoryIowa State University

Porcine Epidemic Diarrhea Virus Update

Darin MadsonISU-VDL

[email protected]


Porcine Epidemic Diarrhea Virus

• Coronavirus– TGE-like outbreaks England 1971

• Multiple European Countries» Most often in nursery/grow finish pigs

• More recently an issue in Asia» China» Japan» Korea

– Severe epizootic outbreaks

Other swine coronaviruses1. TGE2. PRCV3. HEV



• Difficult to propagate in cell culture• Vero cells with trypsin

– African green monkey kidney cells

• Only one serotype known– European isolates similar to Asian isolates

• US isolate(s)• 99.8% similar to 2012 china isolate in genbank



• Enveloped, single-stranded RNA virus• 7 open reading frames encode 4

structural proteins– Spike protein (S gene)– Membrane (M)– Envelope (E)– Nucleoprotein (N gene)

• Highly conserved; best for testing Dr. E. Burrough





• Transmission– Only infectious to swine

– Not humans or other species

– Fecal-oral transmission• Outbreaks with 4-5 days after pig movements

• Pig-to-pig transmission– Shedding for 7-9 days – No long term virus carriers have been reported to date

• Biosecurity– Trucks, boots, fomites, etc.– Similar to TGE



• Outcomes of infection

– Endemic• Lactogenic immunity is protective to piglets

– Eliminated



• Pathogenesis

– Viral attack of mature villous enterocytes• Diffusely through the small intestine• Cytoplasmic replication• Incubation time = 12-18 hrs• Severe diarrhea at 24-36 hrs (maximum effect)

– Post infection

• Rare detection in colonocytes– No destruction though



Villous to crypt ratio 7:1







Villous to crypt ratio 3:1







• PEDV has not been detected outside the intestinal tract

• Previous reports, anyway• Lung and mesenteric lymph node?

• PEDV is supposedly less severe than TGE

• ISU cases support similar severity to TGE



• Clinical disease– Watery diarrhea

• Smells like TGE (literally if you can smell TGE)• Suckling pigs most severely affected• ~100% morbidity in acute cases• ~50% mortality from dehydration

– Vomiting (possible)





• Properties– Stable between a pH of 5-9– Heat inactivated at 60°C of 30 mins– Moderately stable at 50°C



Pospischil et al 2002



• The story………………..

Case Date Location Farm type

1 04/29/13 Iowa Sow

2 05/01/13 Iowa Sow

3 05/06/13 Iowa Nursery

4 05/06/13 Iowa Nursery

5 05/07/13 Indiana Sow

6 05/08/13 Indiana Sow



• All cases had severe diarrhea – Some vomiting

• All TGE negative– Samples sent to SDSU and Minnesota as well

• Severe atrophic enteritis• Sent feces to NVSL for Election

microscopy (EM)– Positive for coronavirus-like particle (5-10-13)



• NVSL PCR testing for PEDV– Positive on 5-11-2013

• Announcement – 5-17-2013

• My life changed 5-17-2003






Available PEDv Diagnostics

• PCR• Multiple PCR tested• S gene, N gene, and nested• Currently running

– N gene real-time– S gene gel based is the back up– Nested is the third confirmatory test

• PCR samples– Feces, intestine, oral fluids, feed, Swiffer

Retrospective testing – 800+ samples


Available PEDv Diagnostics

• Immunohistochemistry– Fixed samples

• Not as sensitive as PCR

• Serology– IFA (very soon)

• Dr. Yoon’s Lab has been able to culture the virus

– ELISA not yet

IHC development 5-25-2013No retrospective testing to date


PEDv Research and Hearsay

• Feed; potential infection source??????– Numerous samples tested

• Whole feed, premixes, plasma sources, etc.

• 2 samples positive on multiple PCRs– Vitamin premix– Plasma product

• Infectivity unknown– Swine bioassays needed


PEDv Research

• Pathogenesis studies underway– Weaned pig study– Neonatal pig study

• Evaluating• Shedding• Oral fluid detected• Microscopic lesions • Clinical signs


PEDv Research

Weaned Pig Study• Diarrhea 2-3 days post

inoculation• Little vomiting @ 3-4 days• Extensive diarrhea @ 4-6

days post inoculation• Recovery @ 8 days; no

depression with scant diarrhea

• No weight gain for 7 days• PCR testing N/A yet

Neonatal pig study• Diarrhea at 24 hours post

inoculation• Severe diarrhea at 36

hours; all pigs• Severe emaciation and

dehydration @ 48 hours• Mortality 36-72 hours

Preliminary data


PEDv Research

Weaned pigs DPI 3


PORCINE EPIDEMIC DIARRHEA VIRUS

What is next?????

Questions???Acknowledgments

Dr. Drew MagstadtDr. Paulo ArrudaDr. YoonDr. Stevenson

Health & Medicine

Dr. Darin Madson - Porcine Epidemic Diarrhea Virus Update