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Porcine Interferon α(IFN-α)
ELISA Kit
? This immunoassay kit allows for the in vitro quantitative determination of porcine
IFN-α concentrations in serum, plasma.
? Expiration date six months from the date of manufacture
? FOR RESEARCH USE ONLY. NOT FOR USE IN DIAGNOSTIC PROCEDURES.
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INTRODUCTION
Interferons (IFNs) are natural cell-signaling proteins produced by
the cells of the immune system of most vertebrates in response
to challenges such as viruses, parasites and tumor cells.
Interferons belong to the large class of glycoproteins known as
cytokines. Interferons are produced by a wide variety of cells in
response to the presence of double-stranded RNA, a key
indicator of viral infection. Interferons assist the immune
response by inhibiting viral replication within host cells, activating
natural killer cells and macrophages, increasing antigen
presentation to lymphocytes, and inducing the resistance of host
cells to viral infection. There are three major classes of
interferons that have been described for humans according to
the type of receptor through which they signal: type I, II and III
IFNs.
PRINCIPLE OF THE ASSAY
The microtiter plate provided in this kit has been pre-coated with
an antibody specific to IFN-α. Standards or samples are then
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added to the appropriate microtiter plate wells with a Horseradish
Peroxidase (HRP)-conjugated monoclonal antibody preparation
specific for IFN-α and incubated. Then substrate solution A and
B are added to each well. Only those wells that contain IFN-α,
HRP-conjugated antibody will exhibit a change in color. The
enzyme-substrate reaction is terminated by the addition of a
sulphuric acid solution and the color change is measured
spectrophotometrically at a wavelength of 450 nm ± 2 nm. The
concentration of IFN-α in the samples is then determined by
comparing the O.D. of the samples to the standard curve.
DETECTION RANGE
The standard curve concentrations used for the ELISA’s were
1000 pg/ml, 500 pg/ml, 250 pg/ml, 125 pg/ml, 50 pg/ml, 25pg/ml.
SPECIFICITY
This assay recognizes recombinant and natural porcine IFN-α.
No significant cross-reactivity or interference was observed.
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SENSITIVITY
The minimum detectable dose of porcine IFN-α is typically less
than 12.5 pg/ml. The sensitivity of this assay, or Lower Limit of
Detection (LLD) was defined as the lowest concentration that
could be differentiated from zero.
MATERIALS PROVIDED
Reagent Quantity
Assay plate 1
Standard(S1-S6) 6
HRP-conjugate 1 x 6 ml
Wash Buffer
1 x 15 ml
(20×concentrate)
Substrate A 1 x 6 ml
Substrate B 1 x 6 ml
Stop Solution 1x 6 ml
Standard S1 S2 S3 S4 S5 S6
Concentration
(pg/ml)
25 50 125 250 500 1000
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STORAGE
1. Unopened test kits should be stored at 2-8?C upon receipt
and the microtiter plate should be kept in a sealed bag. The
test kit may be used throughout the expiration date of the kit,
provided it is stored as prescribed above. Refer to the
package label for the expiration date.
2. Opened test plate should be stored at 2-8?C in the aluminum
foil bag with desiccants to minimize exposure to damp air. The
kits will remain stable until the expiring date shown, provided it
is stored as prescribed above.
3. A microtiter plate reader with a bandwidth of 10 nm or less
and an optical density range of 0-3 OD or greater at 450nm
wavelength is acceptable for use in absorbance
measurement.
REAGENT PREPARATION
1. Bring all reagents and plate to room temperature for at least
30 minutes before use. Unused wells need store at 2-8°C and
avoid sunlight.
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2. Wash Buffer If crystals have formed in the concentrate,
warm to room temperature and mix gently until the crystals
have completely dissolved. Dilute 15 ml of Wash Buffer
Concentrate into deionized or distilled water to prepare 300 ml
of Wash Buffer.
Precaution: The Stop Solution provided with this kit is an acid solution. Wear
eye, hand, face, and clothing protection when using this material.
OTHER SUPPLIES REQUIRED
? Microplate reader capable of measuring absorbance at 450
nm, with the correction wavelength set at 540 nm or 570 nm.
? Pipettes and pipette tips.
? Deionized or distilled water.
? Squirt bottle, manifold dispenser, or automated microplate
washer.
? An incubator which can provide stable incubation conditions
up to 37°C±0.5°C.
SAMPLE COLLECTION AND STORAGE
? Serum Use a serum separator tube (SST) and allow
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samples to clot for 30 minutes before centrifugation for 15
minutes at 1000 g. Remove serum and assay immediately or
aliquot and store samples at -20°C. Centrifuge the sample
again after thawing before the assay. Avoid repeated
freeze-thaw cycles.
? Plasma Collect plasma using citrate, EDTA, or heparin as
an anticoagulant. Centrifuge for 15 minutes at 1000 g within
30 minutes of collection. Assay immediately or aliquot and
store samples at -20°C. Centrifuge the sample again after
thawing before the assay. Avoid repeated freeze-thaw cycles.
Note: Grossly hemolyzed samples are not suitable for use in this assay.
ASSAY PROCEDURE
Bring all reagents and samples to room temperature before use. It is
recommended that all samples, standards, and controls be assayed in duplicate.
All the reagents should be added directly to the liquid level in the well. The
pipette should avoid contacting the inner wall of the well.
1. Set a Blank well without any solution. Add 100μl of Standard
or Sample per well. Standard need test in duplicate.
2. Add 50μl of HRP-conjugate to each well (not to Blank well).
Mix well and then incubate for 2 hours at 37°C.
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3. Complete remove the liquid. Then fill each well with Wash
Buffer (about 200μl), stay for 10 seconds and Spinning.
Repeat the process for a total of three washes. Complete
removal of liquid at each step is essential to good
performance. After the last wash, remove any remaining
Wash Buffer by aspirating or decanting. Invert the plate and
blot it against clean paper towels.
4. Add 50μl of Substrate A and 50μl of Substrate B to each
well, mix well. Incubate for 15 minutes at 37°C. Keeping the
plate away from drafts and other temperature fluctuations in
the dark.
5. Add 50μl of Stop Solution to each well. If color change does
not appear uniform, gently tap the plate to ensure thorough
mixing.
6. Determine the optical density of each well within 10 minutes,
using a microplate reader set to 450 nm.
CALCULATION OF RESULTS
Using the professional soft "Curve Exert 1.3" to make a standard curve is
recommended, which can be downloaded from our web.
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Average the duplicate readings for each standard, control, and
sample and subtract the average zero standard optical density.
Create a standard curve by reducing the data using computer
software capable of generating a four parameter logistic (4-PL)
curve-fit. As an alternative, construct a standard curve by plotting
the mean absorbance for each standard on the y-axis against
the concentration on the x-axis and draw a best fit curve through
the points on the graph. The data may be linearized by plotting
the log of the IFN-α concentrations versus the log of the O.D.
and the best fit line can be determined by regression analysis.
This procedure will produce an adequate but less precise fit of
the data. If samples have been diluted, the concentration read
from the standard curve must be multiplied by the dilution factor.
LIMITATIONS OF THE PROCEDURE
? The kit should not be used beyond the expiration date on the
kit label.
? Do not mix or substitute reagents with those from other lots or
sources.
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? If samples generate values higher than the highest standard,
dilute the samples with the appropriate Diluent and repeat the
assay.
? Any variation in operator, pipetting technique, washing
technique, incubation time or temperature, and kit age can
cause variation in binding.
? This assay is designed to eliminate interference by soluble
receptors, binding proteins, and other factors present in
biological samples. Until all factors have been tested in the
Quantikine Immunoassay, the possibility of interference
cannot be excluded.
TECHNICAL HINTS
? Centrifuge vials before opening to collect contents.
? When mixing or reconstituting protein solutions, always avoid
foaming.
? To avoid cross-contamination, change pipette tips between
additions of each standard level, between sample additions,
and between reagent additions. Also, use separate reservoirs
for each reagent.
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? When using an automated plate washer, adding a 30 second
soak period following the addition of wash buffer, and/or
rotating the plate 180 degrees between wash steps may
improve assay precision.
? To ensure accurate results, proper adhesion of plate sealers
during incubation steps is necessary.
? Substrate Solution should remain colorless or light blue until
added to the plate. Keep Substrate Solution protected from
light. Substrate Solution should change from colorless or light
blue to gradations of blue.
? Stop Solution should be added to the plate in the same order
as the Substrate Solution. The color developed in the wells
will turn from blue to yellow upon addition of the Stop Solution.
Wells that are green in color indicate that the Stop Solution
has not mixed thoroughly with the Substrate Solution.
