One-Step Influenza A Test
Cat. No.: RH0210A
One Step Influenza A Test is a rapid qualitative assay that detects
influenza type A (including the subtype H1N1) nucleoprotein antigen
extracted from the nasal swab specimen. The device is used to aid
in the diagnosis of influenza type A infection.
For in vitro diagnostic use only. For professional use only.
Influenza (commonly known as ‘flu’) is a highly contagious, acute
viral infection of the respiratory tract. It is a communicable
disease that is easily transmitted through the coughing and
sneezing of aerosolized droplets containing live virus. Influenza
outbreaks occur each year during the autumn and winter months.
There are three types of influenza viruses: A, B, and C. Only
influenza A viruses are further classified by subtype on the basis
of the two main surface glycoproteins hemagglutinin (HA) and
neuraminidase (NA). Influenza A subtypes and B viruses are further
classified by strains.
Humans can be infected with influenza types A, B, and C viruses.
Subtypes of influenza A that are currently circulating among people
worldwide include H1N1, H1N2, and H3N2 viruses. Influenza B viruses
can cause morbidity and mortality among humans, but in general are
associated with less severe epidemics than influenza A viruses.
Although influenza type B viruses can cause human epidemics, they
have not caused pandemics. Influenza type C viruses cause mild
illness in humans and do not cause epidemics or pandemics.
One Step Influenza A Test is a rapid immunochromatographic test for
the visual detection of influenza type A antigen (nucleoprotein)
extracted from the nasal swab specimen. The test adopts double
antibody sandwich method.
When the extracted specimen is added into the test device, the
specimen is absorbed into the device by capillary action, mixes
with antibody-dye conjugate, and flows across the membrane
pre-coated with influenza type A monoclonal antibody.
When the influenza type A antigen levels are at or above the target
cutoff (the detection limit of the test), type A antigen in the
specimen binds to the specific antibody-dye conjugate and are
captured by influenza type A monoclonal antibody immobilized in the
relative site of test region “T” of the device. This produces a
colored test band in the test region. When the influenza type A
antigen levels are zero or below the target cut off, there is not a
visible colored band in the test region of the device. This
indicates a negative result for influenza type A.
To serve as a procedure control, a colored line will appear at the
control region (C), if the test has been performed properly.
- This kit is for in vitro use only. Do not swallow.
- Do not mix components from different kit lots.
- Do not use test kit beyond the expiration date.
- Do not use the kit if the pouch is punctured or not well sealed.
- Keep out of the reach of children.
- Discard after use. The test device cannot be used more than once.
- The extraction tube and nasal swab are single use items – do not
use with multiple specimens.
- All specimens should be treated as potentially infectious diseases.
Protection glove should be worn when handling the specimen. Wash
hands thoroughly afterwards.
- Avoid splashing or aerosol formation.
- DISPOSAL OF THE DIAGNOSTIC: The used device, swab and extraction
tube have the infectious risk. The process of disposing the
diagnostic must follow the local infectious disposal law or
1.20 Individual sealed pouches, each containing
2. 20 Extraction tubes.
3.20 Nasal swabs.
4. Two dropper bottles of extraction buffer (each 5mL): 0.1M
phosphate buffer saline (PBS).
5. Leaflet with instructions for use.
Material Required But Not Provided
STORAGE AND STABILITY
- Store at 4ºC ~ 30 ºC in the sealed pouch up to the expiration date.
- Keep away from sunlight, moisture and heat.
- DO NOT FREEZE.
SPECIMEN COLLECTION AND PREPARATION
1.Take out the nasal swab provided. Tilt the head of the patient
backwards to the angle of 70° and gently insert the nasal swab into
the nostril which shows the most secretion.
2.Very gently rotate and push the swab until resistance is met at
level of the turbinate. Gently rotate the swab against the nasal
wall for a few times.
3.Patient samples perform best if tested immediately after
If immediate testing is not possible, the swab should be placed in
a dry, sterile plastic tube (not provided) and stored at 2ºC-4ºC
for up to 8 hours.
Allow the test device, specimen, and extraction buffer to
equilibrate to room temperature (10°C ~30°C) prior to testing.
- Use an extraction tube (provided) for each specimen to be tested,
and label each tube appropriately.
- Hold the extraction buffer bottle upside down vertically, then add
8 drops (about 400μl) of extraction buffer to the extraction tube.
- Place the specimen swab in the tube and swirl the swab for 10 times
while pressing the swab head against the inside of the tube to
release the specimen in the swab.
- Remove the swab while squeezing the swab head against the inside of
the collection tube as you remove it to expunge as much liquid as
possible from the swab. Discard the swab. Cap the tube and mix
contents by gently swirling. The extraction specimen must be tested immediately.
- Remove the test device from its sealed foil pouch by tearing at the
notch. Dispense 3~4 drops (80μl~100μl) of extraction specimen from
the extraction tube into the sample well of the test device by
inverting and squeezing the tube as shown.
- Read the test results at 15~20 minutes. DO not read test results after 30 minutes.
INTERPRETATION OF RESULTS
Colored bands are visible in both the control region and the test
region. It indicates a positive result for influenza type A
A colored band is visible only in the control region. No color band
appears in the test region. It indicates that the concentration of
the influenza type A antigen is zero or below the detection limit
of the test.
No visible band at all, or there is a visible band only in the test
region but not in the control region. Repeat with a new test kit. I
Note: There is no meaning attributed to line color intensity or width.
A procedural control is included in the test. A colored line
appearing in the control region (C) is considered an internal
procedural control. It confirms sufficient specimen volume,
adequate membrane wicking and correct procedural technique.
Good laboratory practice recommends the use of the control
materials. Users should follow the appropriate federal state, and
local guidelines concerning the frequency of assaying external
quality control materials.
LIMITATIONS OF PROCEDURE
- This test has been developed for testing nasal swab specimen only.
- As it is with any diagnostic procedure, a confirmed diagnosis
should only be made after all clinical and laboratory findings have
- A negative test result may occur if the level of antigen in a
sample is below the detection limit of the test, or from improper
- Negative test results are not intended to rule-out other
non-influenza viral infections.
- Positive test results do not rule out co-infections with other
pathogens and does not identify specific influenza A virus
The lowest detectable limit
For influenza type A : 5.1×105TCID50/ml
A comparison study of One Step Influenza A Test and another
commercial influenza test (Colloidal gold method) was carried out
in several medical institutions. Nasal swab samples were collected
from adult and child patients exhibiting influenza-like symptoms.
One swab was used to perform the One Step Influenza A Test and one
swab was used for another commercial influenza test analysis.
Compare the sensitivity and specificity between the two tests. The
results are summarized in Table 1.
Table 1: Comparison results
|One Step Influenza A Test||The reference test||Total|
|Influenza A positive||Influenza A negative|
|Influenza A positive||284||37||321|
|Influenza A negative||27||745||772|
(1) Sensitivity of One Step Influenza A Test is: 284/311×100％＝91.3％
(2) Specificity of One Step Influenza A Test is: 745／782×100％＝95.7％
One Step Influenza A Test was tested with the following influenza A
viral strains listed in Table 2. All showed positive results.
Although the specific influenza A strains causing infection in
humans can vary year to year, all contain the conserved
nucleoproteins targeted by the One Step Influenza A Test.
Table 2: Influenza A viral trains
|Influenza type A|
To determine the analytical specificity (cross-reactivity) of the
One Step Influenza A Test, 27 commensal and pathogenic
microorganisms (16 bacteria, and 11 viruses) that may be present in
the nasal cavity were tested. All of the following microorganisms
were negative when tested at concentrations ranging from 104 to 108 TCID50/ml (viruses), 107 to 108 organisms/ml (bacteria).
|Escherichia coli||Cytomegalovirus (CMV)|
|Haemophilus influenzae||Human influenza type B virus|
|Lactobacillus casei||Human influenza type C virus|
|Moraxella catarrhalis||Mumps virus|
|Neisseria meningitidis||Parainfluenza 1|
|Neisseria sicca||Parainfluenza 2|
|Pseudomonas aeruginosa||Parainfluenza 3|
|Staphylococcus aureus||Respiratory syncytial virus (RSV)|
|Streptococcus, Group A|| |
|Streptococcus, Group B|
|Streptococcus, Group C|
|Streptococcus, Group F|
Within and between run precision was determined by using 10
replicates of one influenza A positive sample in 3 different lots
of test devices. The negative and positive values were correctly
identified 100% of the time.
BIBLIOGRAPHY OF SUGGESTED READING
- Ruef C.: Diagnosing influenza-clinical assessment and/or rapid
antigen testing?. Infection 2007; 35: 49–50.
- P. Pothier, G. A. Denoyel etc.: Use of Monoclonal Antibodies for
Rapid Detection of Influenza A Virus in Nasopharyngeal Secretions.
Eur. J. Clin. Microbiol., June 1986, p. 336-339.
- Constance T. Pachucki, MD.: Rapid Tests for Influenza. Current
Infectious Disease Reports 2005, 7:187–192
- B. A. Cunha: The Clinical Diagnosis of Severe Viral Influenza A. Infection 2008; 36: 92–93.
- Kilbourne ED: The influenza viruses and influenza. Academic Press,
Bell, D. M., Walsh, E. E., ttruska, J. F., Sehnabel, K. C., Hall,
B.C.: Rapid detection of respiratory syncytical virus with a
monoclonal antibody. Journal of Clinical Microbiology 1983, 17:
Span Biotech Ltd. is a research based company for rapid tests, with
strong support from National Key Laboratory of Technology Projects
of 10th and 11th Five-Year Plan and Faculty of Life Sciences of HuBei University.
SpanBio also housed a R&D team that is developing gene
recombination, cell cultivation and protein purification
techniques. SpanBio pays strict attention on rapid tests for human
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