For Research Use Only
Not for Diagnostic Use
Catalog #: WE7196
Two-step Incubation, Antibody Capture Principle
This HEV IgM kit is an enzyme-linked immunosorbent
assay (ELISA) for qualitative determination of IgM-class
antibodies to hepatitis E virus in human serum or plasma.
For Research Use Only
Hepatitis E virus (HEV) is a non-enveloped, singlestranded RNA virus identified in 1990. Infection with HEV
induces acute or sub-clinical liver diseases similar to
hepatitis A. HEV infections, endemic and frequently
epidemic in developing countries, is seen also in
developed countries in a sporadic form with or without a
history of traveling to endemic area. The overall casefatality is 0.5~3%, and much higher (15~25%) among
pregnant women. A hypothesis that HEV infection is a
zoonosis was presented in 1995. Then a swine HEV and
later an avian HEV were identified and sequenced
separately in 1997 and 2001. Since then, HEV infection
include anti-HEV, viremia and feces excretion of HEV was
seen in a wide variety of animals, i.e., swine, rodents, wild
monkeys, deer, cow, goats, dogs and chicken in both the
developing and developed countries. A direct testimony
was reported that the consumption of uncooked dear meat
infected with HEV led to acute hepatitis E in human. And
HEV genome sequences can be detected in pork livers
available in the supermarkets in Japan.
With the discovery of conformational epitopes in HEV, HEV
serology was further explored and understood. The
phenomenon of long-lasting and protective antibodies to
HEV was observed which greatly enhance the
understanding to the diagnosis, epidemiology, zoonosisrelated studies and vaccine development.
This kit is a two-step incubation, solid phase antibody
capture ELISA assay in which polystyrene microwell strips
are pre-coated with antibodies directed to human
immunoglobulin M proteins (anti-μ chain). The patient’s
serum/plasma sample is added and during the first
incubation step, any IgM-class antibodies will be captured
in the wells. After washing out all the other components of
the sample and in particular IgG-class antibodies, the
specific HEV IgM captured on the solid phase is detected
by the addition of recombinant HEV ORF2 antigens
conjugated to horseradish peroxidase (HRP-Conjugate).
During the second incubation, the HRP-conjugated
antigens will specifically react only with HEV IgM
antibodies and after washing to remove the unbound
HRP-Conjugate, Chromogen solutions are added into the
In presence of (anti-μ) - (anti-HEV-IgM) - (HEV Ag-HRP)
immunocomplex, the colorless Chromogens are
hydrolyzed by the bound HRP-Conjugate to a blue-colored
product. The blue color turns yellow after stopping the
reaction with sulfuric acid. The amount of color intensity
can be measured and is proportional to the amount of
antibody captured in the wells, and to the sample
respectively. Wells containing samples negative for HEV
IgM remain colorless.
96 Tests
1 plate
Blank microwell strips fixed on white strip holder. The plate
is sealed in aluminum pouch with desiccant. 8×12/12×8well strips wells per plate. Each well contains anti-IgM
antibodies (anti-μ chain). The microwell strips can be
broken to be used separately. Place unused wells or strips
in the plastic sealable storage bag together with the
desiccant and return to 2~8ºC.
1 vial
Blue-colored liquid filled in a vial with green screw cap.
0.5ml per vial.
Protein-stabilized buffer tested non
reactive for HEV IgM. Preservatives: 0.1% ProClin 300.
Ready to use as supplied. Once open, stable for one
month at 2-8ºC
1 vial
Red-colored liquid filled in a vial with red screw cap.
0.5ml per vial. Purified HEV IgM class antibodies diluted
in protein-stabilized buffer. Preservatives: 0.1% ProClin
300. Ready to use as supplied. Once open, stable for
one month at 2-8ºC.
1 vial
Blue liquid in a white vial with blue screw cap. 12ml per
vial. Serum base, casein, and sucrose solution. Ready to
use as supplied. Once open, stable for one month at 28ºC.
1 vial
Red-colored liquid in a white vial with red screw cap. 12ml
per vial. Horseradish peroxidase-conjugated recombinant
HEV antigens. Ready to use as supplied. Once open,
stable for one month at 2-8ºC
1 bottle
Colorless liquid filled in a clear bottle with white screw cap.
50ml per bottle. pH 7.4, 20 × PBS (contains detergent
DILUTE BEFORE USE -The concentrate must be diluted
1 to 20 with distilled/deionized water before use. Once
diluted, stable for one week at room temperature, or for
two weeks when stored at 2-8ºC.
1 vial
Colorless liquid filled in a white vial with green screw cap.
7ml per vial. Urea peroxide solution. Ready to use as
supplied. Once open, stable for one month at 2-8ºC
1 vial
Colorless liquid filled in a black vial with black screw cap.
TMB solution (Tetramethyl benzidine dissolved in citric
acid). 7ml per vial. Ready to use as supplied. Once
open, stable for one month at 2-8ºC
1 vial
Colorless liquid in a white vial with yellow cap. 7ml per
Diluted sulfuric acid solution (2.0M H2SO4). Ready to use
as supplied.
1 unit
For enclosing the strips not in use.
2 sheets
To cover the plates during incubation and prevent
evaporation or contamination of the wells.
1 copy
Freshly distilled or deionized water.
Disposable gloves and timer.
Appropriate waste containers for potentially
contaminated materials.
Disposable V-shaped troughs.
Dispensing system and/or pipette (single or
multichannel), disposable pipette tips.
Absorbent tissue or clean towel.
Dry incubator or water bath, 37±0.5ºC.
Microshaker for dissolving and mixing conjugate with
Microwell reader, single wavelength 450nm or dual
wavelength 450nm and 630nm.
Microwell aspiration/wash system.
freeze-thaw cycles should be avoided. For shipment,
samples should be packaged and labeled
accordance with the existing local and international
regulations for transport of clinical samples and
ethological agents.
Sample Collection: Either fresh serum or plasma
samples can be used for this assay. Blood collected
by venipuncture should be allowed to clot naturally
and completely – the serum/plasma must be
separated from the clot as early as possible as to
avoid hemolysis of the RBC. Care should be taken to
ensure that the serum samples are clear and not
contaminated by microorganisms. Any visible
particulate matters in the sample should be removed
by centrifugation at 3000 RPM for at least 20 minutes
at room temperature, or by filtration on 0.22u filters.
Plasma samples collected into EDTA, sodium citrate
or heparin may be tested, but highly lipaemic, icteric,
or hemolized samples should not be used as they
could give erroneous results in the assay. Do not
heat inactivate samples. This can cause sample
Transportation and Storage: Store samples at 28ºC. Samples not required for assaying within 3 days
should be stored frozen (-20ºC or lower).Multiple
A good washing procedure is essential to obtain
correct and precise analytical data.
It is therefore recommended to use a good quality
ELISA microplate washer, maintained at the best
level of washing performances. In general, no less
than 5 automatic washing cycles of 350-400μl/well
are sufficient to avoid false positive reactions and
high background.
To avoid cross-contaminations of the plate with
sample or HRP-conjugate, after incubation do not
discard the content of the wells but allow the plate
washer to aspirate it automatically.
Anyway, we recommend calibrating the washing
system on the kit itself in order to match the declared
analytical performances. Assure that the microplate
washer liquid dispensing channels are not blocked or
contaminated and sufficient volume of Wash buffer is
dispensed each time into the wells.
In case of manual washing, we suggest to carry out
5 cycles, dispensing 350-400μl/well and aspirating
the liquid for 5 times. If poor results (high
background) are observed, increase the washing
cycles or soaking time per well.
In any case, the liquid aspirated out the strips should
be treated with a sodium hypochlorite solution at a
final concentration of 2.5% for 24 hours, before
liquids are wasted in an appropriate way.
The concentrated Washing solution should be diluted
1 to 20 before use. For one plate, mix 50 ml of the
concentrate with 950ml of water for a final volume of
1000ml diluted Wash Buffer. If less than a whole
plate is used, prepare the proportional volume of
The components of the kit will remain stable through the
expiration date indicated on the label and package when
stored between 2-8 ºC, do not freeze. To assure
maximum performance of this HEV IgM ELISA kit, during
storage protect the reagents from contamination with
microorganism or chemicals.
This kit is intended FOR RESEARCH USE ONLY
The ELISA assay is a time and temperature sensitive
method. To avoid incorrect result, strictly follow the test
procedure steps and do not modify them.
Do not exchange reagents from different lots, or use
reagents from other commercially available kits. The
components of the kit are precisely matched as to
achieve optimal performance during testing.
Make sure that all reagents are within the validity
indicated on the kit box and are of the same lot.
Never use reagents beyond the expiry date stated
on reagents labels or on the kit box.
CAUTION - CRITICAL STEP: Allow the reagents
and samples to stabilize at room temperature (1830ºC) before use.
Shake reagent gently before, and return to 2-8ºC
immediately after use.
Use only sufficient volume of sample as indicated in
the procedure steps. Failure to do so may cause in
low sensitivity of the assay.
Do not touch the bottom exterior of the wells;
fingerprints or scratches may interfere with microwell
When reading the results, ensure that the plate
bottom is dry and there are no air-bubbles inside the
Never allow the microplate wells to dry after the
washing step. Immediately proceed to the next step.
Avoid the formation of air-bubbles when adding the
Avoid assay steps long time interruptions. Assure
same working conditions for all wells.
Calibrate the pipette frequently to assure the
accuracy of samples/reagents dispensing. Always
use different disposal pipette tips for each specimen
and reagents as to avoid cross-contaminations.
Never pipette solutions by mouth. The use of
automatic pipettes is recommended.
Assure that the incubation temperature is 37ºC
inside the incubator.
When adding samples, avoid touching the well’s
bottom with the pipette tip.
When reading the results with a plate reader, it is
recommended to determine the absorbance at
450nm or at 450nm with reference at 630nm.
All specimens from human origin should be
considered as potentially infectious.
Materials from human origin may have been used in
the kit. These materials have been tested with tests
kits with accepted performance and found negative
for antibodies to HIV ½, HCV, TP and HBsAg.
However, there is no analytical method that can
assure that infectious agents in the specimens or
reagents are completely absent. Therefore, handle
reagents and specimens with extreme caution as if
capable of transmitting infectious diseases. Strict
adherence to GLP (Good Laboratory Practice)
regulations can ensure the personal safety. Never
eat, drink, smoke, or apply cosmetics in the assay
Bovine derived sera may have been used in this kit.
Bovine serum albumin (BSA) and fetal calf sera
(FCS) are derived from animals from BSE/TSE freegeographical areas.
The pipette tips, vials, strips and sample containers
should be collected and autoclaved for 1hour at
121ºC or treated with 10% sodium hypochlorite for
30minutes to decontaminate before any further steps
for disposal.
The Stop solution (2M H2SO4 ) is a strong acid.
Corrosive. Use it with appropriate care. Wipe up
spills immediately or wash with water if come into
contact with the skin or eyes. ProClin 300 used as a
preservative can cause sensation of the skin.
The enzymatic activity of the HRP-conjugate might
be affected from dust, reactive chemical, and
substances like sodium hypochlorite, acids, alkalis
etc. Do not perform the assay in the presence of
such substances.
Materials Safety Data Sheet (MSDS) available upon
If using fully automated microplate processing
system, during incubation, do not cover the plates
with the plate cover. The tapping out of the
remainders inside the plate after washing, can also
be omitted.
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Reagents Preparation: Allow the reagents and
samples to reach room temperature. (18-30C)
for at least 15-30minutes.Check the Wash buffer
concentrate for the presence of salt crystals. If
crystals have formed in the solution, resolubilize
by warming at 37ºC until crystals dissolve. Dilute
the Wash buffer 1:19 with distilled or deionized
water. Use only clean vessels to dilute the Wash
buffer. Mark three wells as Negative control (e.g.
B1, C1, D1), two wells as Positive control (e.g.
E1, F1) and one Blank. (e.g. A1, neither samples
or HRP-Conjugate should be added into the
Blank well). If the results will be determined by
using dual wavelength plate reader, the
requirement for use of Blank well could be
omitted. Use only number of strips required for
the test.
Adding Diluent: Add 100l Specimen Diluent
into each well.
Adding Sample: Add 10μl of samples and 10μl
Positive and Negative controls and into their
respective wells. Note: Use a separate disposal
pipette tip for each specimen, Negative and
Positive Control as to avoid crosscontamination.
Incubating Sample (1): Cover the plate with the
plate cover and incubate for 30minutes at 37C.
It is recommended to use thermostat-controlled
water tank to assure the temperature stability and
humidity during incubation. If dry incubator is
used, do not open the door frequently.
Washing(2): After the end of the incubation
remove and discard the plate cover. Wash each
well 5 times with diluted Washing buffer. Each
time allow the microwells to soak for 30-60
seconds. After the final washing cycle, turn down
the plate onto blotting paper or clean towel and
tap it to remove any remainders.
Adding HRP-Conjugate: Add 100l of HRPConjugate Reagent into each well except for the Blank.
Step 7
Step 8
Step 9
Step 10
Step 11
Incubating HRP-Conjugate(2): Cover the plate
with the plate cover and incubate for 30minutes
at 37ºC.
Washing (2): Remove and discard the plate
sealer. Aspirate the liquid and rinse each well 5
times with Wash buffer (as step 5). After the final
washing cycle, turn the strips plate and tap out
any remainders.
Coloring: Add 50l of Chromogen A and 50l
Chromogen B solution into each well including
the Blank. Incubate the plate at 37ºC for 15
minutes avoiding light. The enzymatic reaction
between the Chromogen solutions and the HRPConjugate produces blue color in Positive control
and HEV IgM positive sample wells.
Stopping Reaction: Using a multichannel
pipette or manually, add 50l Stop solution into
each well and mix gently. Intensive yellow color
develops in Positive control and HEV IgM
positive sample wells.
Measuring the Absorbance: Calibrate the plate
reader with the Blank well and read the
absorbance at 450nm. If a dual filter instrument
is used, set the reference wavelength at 630nm.
Calculate the Cut-off value and evaluate the
results. (Note: read the absorbance within 5
minutes after stopping the reaction)
Each microplate should be considered separately when
calculating and interpreting results of the assay,
regardless of the number of plates concurrently
processed. The results are calculated by relating each
sample’s optical density (OD) value to the Cut-off value
(C.O.) of the plate. If the Cut-off reading is based on single
filter plate reader, the results should be calculated by
subtracting the Blank well OD value from the print report
values of samples and controls. In case the reading is
based on Dual filter plate reader, do not subtract the Blank
well OD from the print report values of samples and
1. Calculation of Cut-off value (C.O.) = *NC + 0.26
*NC = the mean absorbance value for three negative
If one of the Negative Control values does not meet the
1. Calculation of NC:
Well No
Negative controls OD value 0.02 0.012 0.016
2. Calculation of Cut-off : C.O.= 0.016 + 0.26=0.276
Quality control range specifications, it should be discarded
and the mean value is calculated again using the
remaining two values. If more than one negative control
OD value does not meet the Quality control range
specifications, the test is invalid and must be repeated.
2. Quality control range:
The test results are valid if the Quality control criteria are
verified. It is recommended that each laboratory must
establish appropriate quality control system with quality
control material similar to or identical with the patient
sample being analyzed.
1. The OD value of the Blank well, which contains only
Chromogens and Stop solution, is less than 0.080 at
450 nm.
2. The OD value of the Positive control must be equal to
or greater than 0.800 at 450/630nm or at 450nm after
3. The OD value of the Negative control must be less
than 0.100 at 450/630nm or at 450nm after blanking.
3. Interpretations of the results:
(S = the individual absorbance (OD) of each specimen)
Negative Results (S/C.O.<1) : Samples giving
absorbance less than the Cut-off value are negative for
this assay, which indicates that no IgM-class antibodies to
hepatitis E virus have been detected with this kit
Positive Results(S/C.O.≥1) : Samples giving an
absorbance equal to, or greater than the Cut-off value are
considered initially reactive, which indicates that IgM-class
antibodies to hepatitis E virus have probably been
detected using this HEV IgM ELISA kit. Retesting in
duplicates of any initially reactive sample is
recommended. Repeatedly reactive samples could be
considered positive for IgM-class antibodies to HEV
Borderline (S/C.O. =0.9-1.1) : Samples with absorbance
to Cut-off ratio between 0.9 and 1.1 are considered
borderline and retesting of these samples in duplicates is
recommended to confirm the results. Repeatedly positive
samples could be considered positive for IgM-class
antibodies to HEV.
1. Non-repeatable positive result may occur due to the
general biological and biochemical characteristics of
ELISA assays. The test is designed to achieve very
high performance characteristics of sensitivity and
specificity. However, antibodies may be undetectable
during the early stages of the disease and in some
immunosuppressed individuals.
2. If, after retesting of the initially reactive samples, the
assay results are negative , these samples should be
considered as non-repeatable (false positive) and
interpreted as negative. As with many very sensitive
ELISA assays, false positive results can occur due to
the several reasons, most of which are related but not
limited to inadequate washing step.
3. Common sources for mistakes: kits beyond the expiry
date, bad washing procedures, contaminated reagents,
incorrect assay procedure steps, insufficient aspiration
during washing, failure to add samples or reagents,
equipment, timing, volumes, sample nature and quality.
4. The prevalence of the marker will affect the assay’s
predictive values.
5. False negative results can occur from inhibition of
specific IgM in the presence of high titers of specific
IgG. The removal of IgG can be helpful to prevent false
negative results and methods for this are given
6. This is a qualitative assay and the results cannot be use
to measure antibodies concentrations.
Chin J Cell Mol Immunol, 2002, 18(6): 617-620
11. Li XL, Ren H, Liang XH, et al. Detection of anti-virus
antibody in sera from patients with hepatitis E after tenyear-infection.
1. Values of the Positive or Negative controls ,which are out
of the indicated Quality control range, are indicator of
possible deterioration of the reagents and/or operator or
equipment errors. In such case, the results should be
considered as invalid and the samples must be
retested. In case of constant erroneous results
classified as due to deterioration or instability of the
reagents, immediately substitute the reagents with new
2. If after mixing of the Chromogen A and B solutions into
the wells, the, the color of the mixture turns blue within
few minutes, do not continue carrying out the testing
and replace the reagents with fresh ones.
Please do not use this kit beyond the expiry
date indicated on the kit box and reagent
1. Reyes GR, Purdy MA, Kim JP, et al. Isolation of a
cDNA from the virus responsible for enterically
transmitted non-A, non-B hepatitis. Science 1990; 247:
2. Clayson E, Innis B, Myint K, et al. Detection of
hepatitis E virus infections among domestic swine in
the Kathmandu Valley of Nepal. Am J Trop Med
3. Meng XJ, Purcell RH, Halbur PG, et al. A novel virus in
swine is closely related to the human hepatitis E virus.
Proc Natl Acad Sci USA, 1997, 94: 9860–9865.
4. Tei S, Kitajima N, Takahashi K, et al. Zoonotic
transmission of hepatitis E virus from deer to human
beings. Lancet 2003; 362(9381):371
5. Zheng YJ, Zhang J, Xia NS. A debate about that
hepatitis E is a zoonosis. Chinese J Zoonosis (in press)
6. Wang YC, Zhang HY, Xia NS, et al. Prevalence,
Isolation, and Partial Sequence Analysis of Hepatitis E
Virus From Domestic Animals in China. J Med Virol
7. Zhang J, Ge SX, Huang GY, et al. Two Hepatitis E
Virus Neutralization Sites analyzed by monoclonal
antibodies raised against a recombinant peptide of
virus capsid protein. J Virol 2003(in press)
8. Zhang J, Ge SX, Huang GY, et al. Evaluation of
antibody based and nucleic acid based assays for
diagnosis of hepatitis E virus infection in a rhesus
monkey model. J Med Virol 2003 (in press)
9. Li SW, Zhang J, He ZQ, et al. The study of aggregate
of the ORF2 peptide of hepatitis E virus expressed in
10. Gu Y, Zhang J, Li SW, et al. Characterization of the
anti-HEV ORF2 monocloneal antibodies by biosensor.
Express Biotech International
P.O. BOX 458
Thurmont, MD 21788 USA
Tel: 301-228-2444 Fax: 301-560-6570
Toll Free: 888-562-8914
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