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Role of passively administered systemic antibodies in protecting
piglets from PEDV
K Poonsuk, LG Giménez-Lirola, J Zhang, P Arruda, Q Chen, L Correa da Silva Carrion, R Magtoto, P Piñeyro, L Sarmento, C Wang, KJ
Yoon, J Zimmerman, R MainIowa State University
PEDV protection?• Maternal immunity important in protection• What is the role of colostral antibodies in
protecting piglets from PEDV?– Experimental model based on "passive antibody
transfer model", i.e., parenterally administered antibody.
Objective of the study• Identify effect of passively administered PEDV-
specific Ab on: 1) Body weight2) Body temperature3) Survival4) Fecal shedding5) Humoral immune response
Experimental design (overview)• Source of "passive antibody"
– Serum from PEDV Ab+ sows (n = 2)– Salt out/concentrate antibody
• Treatments (n = 6) randomized to piglets w/n litters – All litters received all treatments
• Piglets inoculated with PEDV– Observed/sampled for 14 days
PEDV immune sows (n = 2)
Euthanized
Preparation of "passive" antibody
Blood Serum
RBCs
Serum
Ab purification & concentration
Blood
PEDV Ab negative sows (n = 6)
(~110 days gestation)
Piglets (n = 62)
6 Treatment groups
IP inoculation-1 DPI
Anti-PEDVantibody
PEDV CHALLENGE1x 103 TCID50/ml
Challenge0 DPI
Animal study
DATA- Clinical outcomes- PEDV shedding in feces- Serum/milk Ab profile
WV IgG ELISA: S/P < 0.6IFA titer < 8
Treatments• Treatments randomized to piglets by sow– All litters received all treatments
• Randomized block design TREATMENT DilutionTreatment 1 0Treatment 2 1:80Treatment 3 1:160Treatment 4 1:320Treatment 5 1:640Treatment 6 1:1280
Treatments - all litters received all treatments
Litter No. of piglets
Treatments (no. piglets within treatments) Piglet age (days)
at DPI 01 2 3 4 5 6
1 13 2 3 2 2 2 2 52 11 2 1 2 2 2 2 43 9 1 2 1 2 2 1 44 10 2 1 2 1 1 3 45 10 2 2 1 2 2 1 46 9 2 2 2 1 1 1 4Σ 62 12 12 13 13 12 12
PEDV inoculum• PEDV USA/IN/2013/19338E (Vero cells)– 7th passage of the virus
• Inoculation– 1 x 103 TCID50 per ml– Mixed with milk replacer (1:4)– 5 ml given orally
Daily clinical assessment
• Survival• Piglet weight• Body temperature
Sample collection• Serum samples (-4, 0, 14)• Milk samples (daily)– centrifuge 13,000 x g, 15 min, 4 ⁰C
• Fecal samples (daily)– 1 g + 1 ml PBS (1X)
Testing• Antibody profile– Sow milk and piglet serum samples– PEDV FFN, IgG, and IgA ELISA assays
• PEDV shedding – Individual piglet fecal swab samples– PEDV real time RT-PCR
Data analysis• Linear mixed models– Body weight– Body temperature– Fecal shedding
(PEDV rRT-PCR Cq)• Hazard regression
analysis– Compare survival x trt
• Kruskal-Wallis test– Compare time to death
x litter • Wilcoxon rank test
– Antibody responses (WV ELISA IgA, IgG)
Data analysis• Linear mixed models– Body weight– Body temperature– Fecal shedding
(PEDV rRT-PCR Cq)• Hazard regression
analysis– Compare survival x trt
• Kruskal-Wallis test– Compare time to death
x litter • Wilcoxon rank test
– Antibody responses (WV ELISA IgA, IgG)
Data analysis1. Treatment defined as 6 groups
• 5 different PEDV Ab levels (trt. 2 to 6)• 1 antibody-negative control (trt. 1)
IF NO DIFFERENCE DETECTED … then 2. Treatment defined as 2 groups
• Group 1: Antibody-positive (trt. 2+3+4+5+6)• Group 2: Antibody-negative control (trt. 1)
Piglet weight (lb)
Piglet weight (lb)
NO SIGNIFICANT DIFFERENCE AMONG TREATMENTS
Piglet body temperature (F)
Piglet body temperature (F)NO SIGNIFICANT DIFFERENCE AMONG 6 TREATMENTS
Piglet body temperature (F)
Feces qRT-PCR (converted CT)
Feces qRT-PCR (converted CT)
NO SIGNIFICANT DIFFERENCE AMONG TREATMENTS
Survival (%)
Assay (piglet serum) TreatmentDay post inoculation
-4 0a 14
FFN arithmetic mean
1 <1:8 <1:8 1:642 <1:8 1:5.3 1:19.73 <1:8 1:6.1b 1:19.74 <1:8 1:8.0b 1:32.05 <1:8 1:17.1b 1:11.36 <1:8 1:32.0b 1:16.0
PEDV IgA ELISA least square mean S/P
1 0.5 0.2 2.22 0.7 0.7 2.03 0.6 1.1 1.94 0.6 1.8b 1.35 0.6 2.8b 1.26 0.7 3.3b 1.4
PEDV IgG ELISA least square mean S/P (SE)
1 0.6 0.5 1.72 0.7 0.7b 1.03 0.7 0.7b 1.54 0.7 0.8b 1.35 0.7 1.1b 1.06 0.7 1.4b 0.9
a 24 hours following intraperitoneal administration of concentrated PEDV antibody
a 24 hours following intraperitoneal administration of concentrated PEDV antibody
Assay (piglet serum) TreatmentDay post inoculation
-4 0a 14
FFN arithmetic mean
1 <1:8 <1:8 1:642 <1:8 1:5.3 1:19.73 <1:8 1:6.1b 1:19.74 <1:8 1:8.0b 1:32.05 <1:8 1:17.1b 1:11.36 <1:8 1:32.0b 1:16.0
PEDV IgA ELISA least square mean S/P
1 0.5 0.2 2.22 0.7 0.7 2.03 0.6 1.1 1.94 0.6 1.8b 1.35 0.6 2.8b 1.26 0.7 3.3b 1.4
PEDV IgG ELISA least square mean S/P (SE)
1 0.6 0.5 1.72 0.7 0.7b 1.03 0.7 0.7b 1.54 0.7 0.8b 1.35 0.7 1.1b 1.06 0.7 1.4b 0.9
a 24 hours following intraperitoneal administration of concentrated PEDV antibody
Assay (piglet serum) TreatmentDay post inoculation
-4 0a 14
FFN arithmetic mean
1 <1:8 <1:8 1:642 <1:8 1:5.3 1:19.73 <1:8 1:6.1b 1:19.74 <1:8 1:8.0b 1:32.05 <1:8 1:17.1b 1:11.36 <1:8 1:32.0b 1:16.0
PEDV IgA ELISA least square mean S/P
1 0.5 0.2 2.22 0.7 0.7 2.03 0.6 1.1 1.94 0.6 1.8b 1.35 0.6 2.8b 1.26 0.7 3.3b 1.4
PEDV IgG ELISA least square mean S/P (SE)
1 0.6 0.5 1.72 0.7 0.7b 1.03 0.7 0.7b 1.54 0.7 0.8b 1.35 0.7 1.1b 1.06 0.7 1.4b 0.9
Assay (piglet serum) TreatmentDay post inoculation
-4 0a 14
FFN arithmetic mean
1 <1:8 <1:8 1:642 <1:8 1:5.3 1:19.73 <1:8 1:6.1b 1:19.74 <1:8 1:8.0b 1:32.05 <1:8 1:17.1b 1:11.36 <1:8 1:32.0b 1:16.0
PEDV IgA ELISA least square mean S/P
1 0.5 0.2 2.22 0.7 0.7 2.03 0.6 1.1 1.94 0.6 1.8b 1.35 0.6 2.8b 1.26 0.7 3.3b 1.4
PEDV IgG ELISA least square mean S/P (SE)
1 0.6 0.5 1.72 0.7 0.7b 1.03 0.7 0.7b 1.54 0.7 0.8b 1.35 0.7 1.1b 1.06 0.7 1.4b 0.9
b Treatment 2-6 showed
Ab levels significantly
different from treatment 1
(p < 0.02)
a 24 hours following intraperitoneal administration of concentrated PEDV antibody
Assay (piglet serum) TreatmentDay post inoculation
-4 0a 14
FFN arithmetic mean
1 <1:8 <1:8 1:642 <1:8 1:5.3 1:19.73 <1:8 1:6.1b 1:19.74 <1:8 1:8.0b 1:32.05 <1:8 1:17.1b 1:11.36 <1:8 1:32.0b 1:16.0
PEDV IgA ELISA least square mean S/P
1 0.5 0.2 2.22 0.7 0.7 2.03 0.6 1.1 1.94 0.6 1.8b 1.35 0.6 2.8b 1.26 0.7 3.3b 1.4
PEDV IgG ELISA least square mean S/P (SE)
1 0.6 0.5 1.72 0.7 0.7b 1.03 0.7 0.7b 1.54 0.7 0.8b 1.35 0.7 1.1b 1.06 0.7 1.4b 0.9
Assay (piglet serum) TreatmentDay post inoculation
-4 0a 14
FFN arithmetic mean
1 <1:8 <1:8 1:642 <1:8 1:5.3 1:19.73 <1:8 1:6.1b 1:19.74 <1:8 1:8.0b 1:32.05 <1:8 1:17.1b 1:11.36 <1:8 1:32.0b 1:16.0
PEDV IgA ELISA least square mean S/P
1 0.5 0.2 2.22 0.7 0.7 2.03 0.6 1.1 1.94 0.6 1.8b 1.35 0.6 2.8b 1.26 0.7 3.3b 1.4
PEDV IgG ELISA least square mean S/P (SE)
1 0.6 0.5 1.72 0.7 0.7b 1.03 0.7 0.7b 1.54 0.7 0.8b 1.35 0.7 1.1b 1.06 0.7 1.4b 0.9
a 24 hours following intraperitoneal administration of concentrated PEDV antibody
Conclusions• Passively administered antibody affected – Survival– Thermoregulation
• Did not affect– Body weight– PEDV shedding in feces– Antibody responses
IgA response sow milk
IgA response sow milkSows exposed to PEDV
contaminated piglet fecesSows responded differently
IgA response sow milkTreatments were randomized
to sows. This means "sow effect" is accounted for.
Milk IgA - % survival
Milk IgA - % survivalMost of the mortality occured before IgA
levels in sow milk increased
Conclusion• Passive ab protects piglets – Thermoregulation– Survivability
• “Sow effect” was accounted for by experimental design
• Results do not contradict mainstream ideas of PEDV immunity
How might circulating ab affect PEDV infection ?
1. Neutralized PEDV during viremia?2. Facilitated systemic humoral and/or CMI responses?3. Antibody-dependent cell-mediated cytotoxicity
(ADCC)?4. Transported IgG neutralized PEDV in the intestinal
lumen and/or assisted the GI humoral and CMI responses?
Acknowledgement• Funding from the National Pork Board• Thanks to collaborators– Luis G Giménez-Lirola– Marisa Rotolo– Qi Chen– Lucas Correa da Silva Carrion– Chris Olsen– Ronaldo Magtoto
Questions?
The 2015 North American PRRS Symposium wishes to thank the following sponsors for their generous
support: