1. IDEXX PRRS OF Ab Test
Test With Confidence™
Testing swine oral fluids is a convenient and
cost-effective method for PRRS monitoring and
surveillance in commercial herds
By collecting the oral fluids remaining after Testing oral fluids provides a more comprehensive picture of herd status
a pig chews on a rope hanging within the compared to bleeding a random selection of the herd. It is also a less
pen, individual or groups of pigs can be invasive means of sample collection. In this comparison, results show that
surveyed for exposure to the Porcine the new IDEXX PRRS OF Ab Test is optimized for the detection of antibodies
Reproductive & Respiratory Syndrome to PRRSV from individual or collected samples of swine oral fluids (Figure 1),
(PRRS) virus. in less than four hours.
• Cost-effective and convenient Figure 1. Comparison of test protocols
• ess invasive sample collection
L
• Optimized for detection of antibodies in
PRRS X3 Ab Test
less than four hours
Swine Serum
• 98% specificity and sensitivity 2.5µL sample input/well Read at
substrate 650 nm
• For disease monitoring and surveillance conjugate
30 min 30 min 15 min STOP
HR P
HR P
HRP
P
HRP
HRP
P
HRP
HR P
HRP
P
HRP
HR
HR
HR
PRRS
Antigen
2h 30 min 15 min STOP
Swine Oral Fluid Read at
50µL sample input/well 450-650 nm
IDEXX PRRS OF Ab Test

2. IDEXX PRRS OF Ab Test
Protocol Field Studies
This assay follows the same protocol Sample Set 1
as the IDEXX PRRS X3 Ab Test with the Oral fluids reference standards: These reference standards are composed
following protocol modifications: of a temporal series of pooled oral fluids collected from pens of pigs
• ample input is 50 μl/well (diluted 1:2 in
S vaccinated with type 2 modified live vaccine (Ingelvac® PRRS® MLV,
sample diluent to a final volume of 100 μl) Boehringer Ingelheim Vetmedica Inc.) and collected at at 0, 10, 15, 20, 28,
35, 41, 49, 56, 75, and 91 days postvaccination (DPV).2
• here is a 2-hour sample incubation step at
T
room temperature. Sample Set 2
• he final substrate color changes from blue to
T Oral fluids from individual boars: Samples of swine oral fluids paired with
yellow, so final absorbance is read at 450 nm serum from boars sampled at -7 to 0 days pre-inoculation (confirmed
with a reference wavelength (Aref) of seronegative status) and 21 days post-inoculation (confirmed seropositive
620 nm to 650 nm (A450 - Aref) status) were tested with the IDEXX PRRS OF Ab Test and compared with
results obtained in paired serum using the PRRS X3 Ab Test. The boar
An S/P ≥0.4 is considered a positive result. population comprised sets of 24 animals vaccinated with modified live
vaccine (MLV), 22 animals inoculated with type I PRRSV strain, 24 animals
inoculated with type II PRRSV strain3, and an additional set of 10 Austrian
pigs vaccinated with type I.
Sample Set 3
Oral fluids from a pen prevalence study: Analysis of performance on pen
samples according to prevalence of antibody-positive pigs in a pen was
based on a study of 500 pigs divided into pens of 25 pigs each.4 Briefly,
pigs vaccinated with modified live vaccine 14 days prior to the day of the
study (at peak of seroconversion for antibodies) were introduced into
pens of pigs seronegative for PRRS antibodies at a different prevalence
of antibody-positive pigs (0%, 4%, 12%, 20%, and 36%), with five pens for
each of the prevalence values. All pigs were bled for confirmation of serum
antibody titers. Oral fluids were collected from each pen by hanging a
cotton rope on the pen for 30 minutes. Five successive 30-minute replicate
collections were done per pen by hanging a separate new rope for each
collection event.
Pen-based oral fluid samples were collected at various levels of prevalence
(0%, 4%, 12%, 20%, and 36%) of vaccinated pigs introduced at 14 days
post-vaccination into pens of PRRS-negative pigs (Sample set 3). The IDEXX
PRRS OF Ab Test detects anti-PRRS antibodies in ≥96% of all collection
events in pens of at least 20% prevalence, and ≥85% in pens of 12%
prevalence (Figure 2).
Figure 2. Performance Analysis
Sample Set 1 7
New IDEXX PRRS OF Ab Test
6 Standard Overnight Protocol 2
5
S/P
4
3
2
1
0
0 10 20 30 40 50 60 70 80 90
DPI (Days Post Infection) Cut-off S/P =0.4

3. Figure 3-1 through Figure 3-4. Type I and Type II Strains Conversion in Both Serum and Oral Fluids
Figures 3-1 through 3-4 show a selection of pigs individually inoculated with type I and II strains, representing the typical conversion of antibodies in both serum and oral fluids.
Analysis indicate little difference between the time of detection of anti-PRRSV antibodies in serum as in oral fluids, as well as similar ability to detect both type I and II strains.
Oral Fluids Serum
IDEXX PRRS OF Ab Test Sample Set 2 Figure 3-1 IDEXX PRRS X3 Sample Set 2 Figure 3-2
PRRS Type I PRRS Type I
7 2.5
6
Boar 26 2.0 Boar 26
Boar 31 Boar 31
5
Boar 48 Boar 48
1.5
S/P
S/P
4
3 1.0
2
0.5
1
0 0.0
0 5 10 15 20 0 5 10 15 20
Oral Fluids Serum
IDEXX PRRS OF Ab Test Sample Set 2 Figure 3-3 IDEXX PRRS X3 Sample Set 2 Figure 3-4
PRRS Type II PRRS Type II
7 2.5
6
Boar 50 2.0 Boar 50
Boar 56 Boar 56
5
Boar 65 Boar 65
1.5
S/P
S/P
4
3 1.0
2
0.5
1
0 0.0
0 5 10 15 20 0 5 10 15 20
DPI (Days Postinfection) DPI (Days Postinfection)
Cutoff S/P =0.4 (same for oral fluids or serum) Cutoff S/P =0.4 (same for oral fluids or serum)
Figure 4. Performance Based on Prevelance
Sample Set 3
Prevalence level #of pens # of collection Average serum Oral fluids: rate of pos events (%)
(rate of PRRS (# of rope collection events S/P of prevalence level
antibody-pos events per pen) vaccinated pigs
IDEXX PRRS OF Standard Overnight
pigs % of pen) (from PRRS X3)
Procedure2
0 5(5) 25 0 0/25(0%) 0/25(0%)
4 5(5) 25 1.57 8/25(32%) 2/25(8%)
12 4(5) 20 1.3 17/20(85%) 12/20(60%)
20 5(5) 25 1.49 24/25(96%) 22/25(88%)
32-36 5(5) 25 1.33 24/25(96%) 22/25(88%)

4. IDEXX PRRS OF Ab Test
Figure 5. Sensitivity and Specificity
Figure 5 summarizes the performance of Sample Set 2
the new IDEXX PRRS Oral Fluids ELISA
compared to results obtained with PRRS X3 Exposure Status
IDEXX PRRS X3 Ab Test
on paired samples of serum and oral fluids,
collected individually from vaccinated or +
Totals –
PRRSV inoculated pigs before and after PRRSV + 78 1 79
PRRS OF Ab Test
exposure (Sample Set 2). The new IDEXX PRRS
– 0 76 76
Oral Fluids ELISA had a sensitivity of 100.0%
and a specificity of 98.7% (with minimum Totals 78 77 155
sensitivity and specificity of 94.2 and 92.2%, 95% Confidence Limits
respectively, at 95% confidence interval). Low CL High CL
Sensitivity 100.0 94.2 100.0
Specificity 98.7 92.2 100.0
Summary
The IDEXX PRRS OF Ab Test accurately References:
detects PRRS antibodies in oral fluid samples 1. Prickett JR and Zimmerman JJ. The development of oral fluid-based diagnostics and applications in veterinary medicine.
Anim Health Res Rev, 11: 207-216 (2010).
providing results in less than four hours, from 2. Kittawornrat A, et al. Detection of porcine reproductive and respiratory syndrome virus (PRRSV) antibodies in oral fluid
non invasive sampling. specimens using a commercial PRRSV serum antibody enzyme-linked immunosorbent assay. J Vet Diagn Invest,
24(2):262-9 (2012).
3. Kittawornrat A, Prickett J, Chittick W, etal. Porcine reproductive and respiratory syndrome virus (PRRSV) in serum and oral
fluid samples from individual boars: will oral fluid replace serum for PRRSV surveillance Virus Res.154(1-2):170-6 (2010).
4. Olsen C, et al. Probability of detecting PRRSV infection using pen-based swine oral fluid specimens as a function of
within-pen prevalence. Manuscript in preparation.
For more information about the IDEXX PRRS OF Ab Test, please
contact your IDEXX representative or visit idexx.com/prrs.
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