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Evaluation of A Rapid IgM-IgG Combined Antibody Test for SARS-CoV-2 Infection: Single Italian Center Study

Authors:
  • Altamedica Fetal–Maternal Medical Centre

Abstract

The need for timely establishment of diagnostic assays of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is demanded in laboratories worldwide. We evaluated the performance of a flow immunoassay which can detect IgM an IgG antibodies simultaneously against SARS-CoV-2 virus in human blood within 15 min. Among the 132 positive novel Coronavirus Disease 19 (COVID-19) cases, 126 tests were consistent with previous quantitative Real Time PCR (qRT-PCR) assays. Among the 62 negative cases, 60 were consistent with qRT-PCR assays except for 2 cases. In this study, 2019-nCOV/COVID-19 IgG/IgM Rapid Test Device showed 95.5% sensitivity and 96.8% specificity. In conclusion, Rapid IgM-IgG Combined Antibody Test showed high detection consistency among all analysed samples. Suggesting that could be used for the rapid screening of SARS-CoV-2 carriers, either symptomatic or asymptomatic.
© 2020 Katia Margiotti, Marina Cupellaro, Sabrina Emili, Alvaro Mesoraca and Claudio Giorlandino. This ope n access
article is distributed under a Creative Commons Attribution (CC -BY) 3.0 license.
American Journal of Infectious Diseases
Research Notes
Evaluation of A Rapid IgM-IgG Combined Antibody Test for
SARS-CoV-2 Infection: Single Italian Center Study
1Katia Margiotti, 2Marina Cupellaro, 2Sabrina Emili, 1Alvaro Mesoraca and 1,2,3Claudio Giorlandino
1Human Genetics Lab, Altamedica Main Centre, Viale Liegi 45, 00198 Rome, Italy
2Department of Biochemistry, Altamedica Main Centre, Viale Liegi 45, 00198 Rome, Italy
3Department of Prenatal Diagnosis, Altamedica, Fetal-Maternal Medical Centre, Viale Liegi 45, 00198 Rome, Italy
Article history
Received: 01-04-2020
Revised: 22-05-2020
Accepted: 20-06-2020
Corresponding Author:
Katia Margiotti
Human Genetics Lab,
Altamedica Main Centre,
Viale Liegi 45,
00198 Rome, Italy
Tel: +39 06 8505805
Fax: +39 068505815
Email: katia.margiotti@artemisia.it
Abstract: The need for timely establishment of diagnostic assays of Severe
Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is demanded in
laboratories worldwide. We evaluated the performance of a flow
immunoassay which can detect IgM an IgG antibodies simultaneously
against SARS-CoV-2 virus in human blood within 15 min. Among the 132
positive novel Coronavirus Disease 19 (COVID-19) cases, 126 tests were
consistent with previous quantitative Real Time PCR (qRT-PCR) assays.
Among the 62 negative cases, 60 were consistent with qRT-PCR assays
except for 2 cases. In this study, 2019-nCOV/COVID-19 IgG/IgM Rapid
Test Device showed 95.5% sensitivity and 96.8% specificity. In conclusion,
Rapid IgM-IgG Combined Antibody Test showed high detection consistency
among all analysed samples. Suggesting that could be used for the rapid
screening of SARS-CoV-2 carriers, either symptomatic or asymptomatic.
Keywords: Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2),
Rapid IgM-IgG Combined Antibody Test, Novel Coronavirus Disease 19
(COVID-19)
Introduction
On December 31th, 2019 China reported first cases
of atypical pneumonia in Wuhan, the capital of Hubei
province. The causative virus was found to be a
betacoronavirus, closely related to the Severe Acute
Respiratory Syndrome Coronavirus (SARS-CoV-1) from
2003 and similar to Sarbecoviruses isolated from bats
(Wu et al., 2020; Zhou et al., 2020). It was therefore
termed SARS-CoV-2 and the disease it causes was
named Corona Virus Disease 2019 (COVID-19)
(CSGICTV, 2020). Several quantitative Real-Time RT-
PCR (qRT-PCT) protocols for detection of SARS-CoV-2
RNA have been developed and approved from Centers
for Disease Control and Prevention Nucleic acid in US
and are now widely employed to diagnose COVID-19
disease (Chu et al., 2020; Corman et al., 2020).
However, qRT-PCR take at least several hours to
complete and require certified laboratories, expensive
equipment and trained technicians to operate. Moreover,
these methods are dependent on the time‐window of
viral replication and they can potentially cause low
predictive rate results, thereby limiting the usefulness of
RT‐PCR in the field. Therefore, there is an urgent need
for additional tests, rapid and simple to use, to quickly
identify infected patients of SARS-CoV-2 virus,
especially by detecting IgM antibodies which are
observed about 12 day after infection, to prevent virus
transmission of infected patients (Infantino et al., 2020;
Okba et al., 2020; Zhao et al., 2020). However, it is
important to underline that the detection of
SARS‐CoV‐2 viral nucleic acid by RT‐PCR test is still
the current standard diagnostic method for COVID‐19.
At this time a great number of different rapid assays
have been proposed, but lack of analytical performance
and clinical validation are a major problem in terms of
reliability despite the easy access on the market of these
type of test (Rashid et al., 2020; Cassaniti et al., 2020).
The major type are serological assays based on colloidal
gold-labeled Immunochromatography (ICT) methods that
offer combination IgM and IgG detection (Rashid et al.,
2020). All these kits are based and use capture reaction
to detect SARS-CoV-2 IgM/IgG. For combination IgM
and IgG kit, the cassette has two detection bands (M and
G) and a quality control band (C). The M band is coated
with a monoclonal anti-human IgM antibody for
detecting SARS-CoV-2 antibody; the G line is fixed with
a reagent for detecting SARS-CoV-2 antibody; C line is
Katia Margiotti et al. / American Journal of Infectious Diseases 2020, 16 (2): 85.88
DOI: 10.3844/ajidsp.2020.85.88
86
fixed with a quality control antibody. All kits offer a
one-step method with results obtained within 15 min.
Samples that can be used are whole blood, serum or
plasma samples (Li et al., 2020). Recently, has been
reported that the detection accuracy of lateral flow
immunoassay anti-SARS-CoV-2 IgM and IgG antibodies
resulted in a sensitivity of 88.7% and a specificity of
90.6% (Li et al., 2020). The aim of this study was to
assess the diagnostic performance of a newly developed
lateral flow immunoassay anti-SARS-CoV-2 IgM and IgG
antibodies test, developed by using a combination of anti-
IgM-IgG Coronavirus 19 antibodies (2019-
nCOV/COVID-19 IgG/IgM Rapid Test Device,
Hangzhou Realy Tech Co., Ltd). Serological studies in
Italy and around the world appear to be still under
evaluation and reporting available laboratory data is
crucial in order to understand the utility of rapid antibody
detection during the course of SARS-CoV-2 infection.
Materials and Methods
Sample Collection
These samples were collected from various public
healthcare center and COVID-19 accredited healthcare
facilities in Italy, with oral consent from all participants
and approved by the local Ethics Committee of
Artemisia SPA. The 2019-nCOV/COVID-19 IgG/IgM
Rapid Test Device was conducted at Altamedica Medical
Centre (Rome, Italy) by clinical staffs who followed test
procedure described in the product inserts (2019-
nCOV/COVID-19 IgG/IgM Rapid Test Device,
Hangzhou Realy Tech Co., Ltd.)
Sample Testing
The IgM antibody and IgG antibody against SARS-
CoV-2 in blood samples were tested using 2019-
nCOV/COVID-19 IgG/IgM Rapid Test Device
(Hangzhou Realy Tech Co., Ltd) according to the
manufacturer’s instructions. These reagents are supplied
by Hangzhou Realy Tech Co., Ltd and resulted CE
marked and regularly registered with the Ministry of
Italian Health as an IVD Medical Device at N. 1923329.
Briefly, the pouched device was opened immediately
before use. Refrigerated blood samples used for the test,
are warmed to room temperature. During testing, 20 uL
whole blood sample are pipetted into the sample port
followed by adding 2 drops (about 20 uL) of dilution
buffer to drive capillary action along the strip. The entire
test took about 15 min to finish.
Data Analysis
The rapid SARS-CoV-2 IgG-IgM combined antibody
test kits were tested on blood samples coming several
hospitals and Italian COVID-19 accredited laboratories
in different provinces, with a total of 132 clinical
positive and 62 clinical negative patient blood samples.
The test performance was calculated with the Vassarstats
online calculator (http://www.vassarstats.net).
Results and Discussion
One hundred and thirty-two patients with qRT-PCR
positive SARS-CoV-2 and sixty-two qRT-PCR negative
SARS-CoV-2 infection were included in the study. No
clinical data were available along with the laboratory
results at that moment. The available characteristics of
the sample testing are reported in Table 1. All sample
were tested for viral antibody with a new 2019-
nCOV/COVID-19 IgG/IgM Rapid Test Device
(Hangzhou Realy Tech Co., Ltd). The sensitivity and
specificity of the rapid test newly developed were
verified in a total of 194 cases: 132 (positive) clinically
confirmed (by qRT-PCR test) SARS-CoV-2-infected
patients and 62 SARS-CoV-2 qRT-PCR negative cases.
In our study of the 132 SARS-CoV-2-infected patients,
126 resulted positive to the antibodies rapid test,
generating a sensitivity of 95.5% (CI95% 89.9-98.1), of
the 62 SARS-CoV-2 negative cases 2 tested positive,
generating a specificity of 95.8% (CI95% 87.8-99.4)
(Table 2). Moreover, the positive predictive value (PPV)
of antibodies test was 98.44% (126/128) and the
Negative Predictive Value (NPV) of antibodies test was
90.1% (60/66). It was also founded that 61.9% (78 out
of 126) of positive patients had both IgM and IgG
antibodies, while 7.9 % (10/126) where IgG positive
and 30% (38/126) where IgM positive. A singular IgM
response is an indication of a recent infection, while a
singular IgG response meaning that the infection was
encountered more than 2 months before the serological
test (Matricardi et al., 2020) (Table 2). Thus, the
antibody testing might play pivotal roles in the
following settings: (1) for suspected paucisymptomatic
patients, positive result of antibody increases the
confidence to make a COVID-19 diagnosis; (2) for
healthy subject, in this case of antibody positive result
the RNA should be tested more frequently and the close
contacts observed as well. Obviously, this test cannot
confirm virus presence, only provide evidence of recent
infection, but it provides an important immunological
evidence for physicians to make the exact diagnosis
along with other tests and to start treatment of patients.
Moreover, rapid laboratory diagnosis is essential for
commencement of infection control measures. Rapid
specific antigen tests have also been widely used in the
diagnosis of two other coronavirus infection disease,
Severe Acute Respiratory Syndrome (SARS) and
Middle East Respiratory Syndrome (MERS) (Lau et al.,
2004; Chen et al., 2016). Testing of specific antibodies
of SARS-CoV-2 in patient blood is a good choice for
rapid, simple, highly sensitive diagnosis of COVID-19.
Katia Margiotti et al. / American Journal of Infectious Diseases 2020, 16 (2): 85.88
DOI: 10.3844/ajidsp.2020.85.88
87
Table 1: Patient characteristics of the COVID-19 and control groups
Characteristics COVID-19 group
Age, years 35.5 (20.5-72.4)
Male sex 56 (42%)
Female sex 76 (58%)
Characteristics Control group
Age, years 32.1 (23.5-67.3)
Male sex 23 (37%)
Female sex 39 (63%)
Table 2: Detection sensitivity and specificity of 2019-nCOV/COVID-19 IgG/IgM rapid test device
qRT-PCR positive qRT-PCR negative
Sample Analysed 132 62
IgG&IgM Positive 78 0
IgG Positive 10 0
IgM Positive 38 2
Sensitivity 95.5% (CI95% 89.9-98.1)
Specificity 96.8% (CI95% 87.8-99.4)
There are some limitation to consider, like possible
cross-reactivity with other coronaviruses and flu viruses.
In fact, SARSCoV-2 belongs to betacoronavirus, in the
same family as SARS-CoV and MERS-CoV. Thus, there
is possibility of cross-reactivity with other coronaviruses
occurring and other bat-related SARS coronaviruses
remains to be clearly determined (Xiao et al., 2020).
Nevertheless, combination of nucleic acid qRT-PCR and
the IgM-IgG antibody test can provide more accurate
SARS-CoV-2 infection diagnosis. As today, only the
Cellex qSARS-CoV-2 IgG/IgM Rapid Test has been
validated by the US Food and Drug Administration (FDA)
in the Emergency Use Authorisation (EUA) category. The
objective of this study was to evaluate the overall clinical
performance and diagnostic value of a rapid serological
testing the 2019-nCOV/COVID-19 IgG/IgM Rapid Test
Device in detecting SARS-CoV-2-infected patients. Our
study represents a private clinical experience of the IgM-
IgG antibody test in an Italian laboratory for SARS-CoV-
2 antibodies detections. In our hands, the performance of
the 2019-nCOV/COVID-19 IgG/IgM Rapid Test Device
was comparable to that of recently published clinical
study, showing that viral serological testing is an effective
means of SARS-CoV-2 infection (Li et al., 2020).
Conclusion
A rapid 2019-nCOV/COVID-19 IgG/IgM Rapid Test
Device using lateral flow immune assay techniques was
evaluated. It takes less than 15 min to generate results
and determine whether there is recent SARS-CoV-2
infection. It is easy to use and no additional equipment is
required. Results from this study demonstrated that this
test is highly sensitive and specific. In conclusion, this
rapid test has great potential benefit for the fast screening
of SARS-CoV-2 infections and it has already generated
enormous interest in the medical community.
Author’s Contributions
Katia Margiotti: Provided insights on data analysis
and result and drafting the manuscript.
Marina Cupellaro and Sabrina Emili: Did the
laboratory analyses.
Alvaro Mesoraca and Claudio Giorlandino:
Conceived the study revised the manuscript.
All authors have approved the final article.
Ethics
The study was approved by the local Ethics
Committee of Artemisia SpA..
References
Cassaniti, I., F. Novazzi, F. Giardina, F. Salinaro and M.
Sachs et al., 2020. Performance of VivaDiag
COVID-19 IgM/IgG rapid test is inadequate for
diagnosis of COVID-19 in acute patients referring to
emergency room department. J. Med. Virol.
Chen, Y., K.H. Chan, C. Hong, Y. Kang and S. Ge
et al., 2016. A highly specific rapid antigen
detection assay for on-site diagnosis of MERS. J.
Infect., 73: 82-84.
DOI: 10.1016/j.jinf.2016.04.014
Chu, D.K.W., Y. Pan, S.M.S. Cheng, K.P.Y. Hui and P.
Krishnan et al., 2020. Molecular diagnosis of a
Novel Coronavirus (2019-NCoV) causing an
outbreak of pneumonia. Clin. Chem., 66: 549-555.
DOI: 10.1093/clinchem/hvaa029
Corman, V.M., O. Landt, M. Kaiser, R. Molenkamp and
A. Meijer et al., 2020. Detection of 2019 Novel
Coronavirus (2019-NCoV) by real-time RT-PCR.
Eurosurveillance.
DOI: 10.2807/1560-7917.ES.2020.25.3.2000045
Katia Margiotti et al. / American Journal of Infectious Diseases 2020, 16 (2): 85.88
DOI: 10.3844/ajidsp.2020.85.88
88
CSGICTV, 2020. The species severe acute respiratory
syndrome-related coronavirus: Classifying 2019-
NCoV and naming it SARS-CoV-2. Nature
Microbiol., 5: 536-544.
DOI: 10.1038/s41564-020-0695-z
Infantino, M., A. Damiani, F.L. Gobbi, V. Grossi and B.
Lari et al., 2020. Serological assays for SARS-CoV-
2 infectious disease: Benefits, limitations and
perspectives. Israel Med. Assoc. J., 22: 203-210.
PMID: 32286019
Lau, S.K.P., P.C.Y. Woo, B.H.L. Wong, H.W. Tsoi and
G.K.S. Woo et al., 2004. Detection of Severe
Acute Respiratory Syndrome (SARS) coronavirus
nucleocapsid protein in SARS patients by enzyme-
linked immunosorbent assay. J. Clin. Microbiol.,
42: 2884-2889.
DOI: 10.1128/JCM.42.7.2884-2889.2004
Li, Z., Y. Yi, X. Luo, N. Xiong and Y. Liu et al., 2020.
Development and clinical application of a rapid
IgM-IgG combined antibody test for SARS-CoV-2
infection diagnosis. J. Med. Virol.
DOI: 10.1002/jmv.25727
Matricardi, P.M., R.W. Dal Negro and R. Nisini, 2020.
The first, comprehensive immunological model of
COVID-19: Implications for prevention, diagnosis
and public health measures.
Okba, N.M.A., M.A. Muller, W. Li, C. Wang and C.H.
GeurtsvanKessel et al., 2020. SARS-CoV-2 specific
antibody responses in COVID-19 patients. Emerg.
Infect. Dis. DOI: 10.1101/2020.03.18.20038059
Rashid, Z.Z., S.N. Othman, M.N. Abdul Samat, U.K. Ali
and K.K. Wong, 2020. Diagnostic performance of
COVID-19 serology assays. Malaysian J. Pathol.,
42: 13-21.
Wu, F., S. Zhao, B. Yu, Y.M. Chen and W. Wang et al.,
2020. A new coronavirus associated with human
respiratory disease in China. Nature, 579: 265-269.
DOI: 10.1038/s41586-020-2008-3
Xiao, S.Y., Y. Wu and H. Liu, 2020. Evolving status of
the 2019 novel coronavirus infection: Proposal of
conventional serologic assays for disease diagnosis
and infection monitoring. J. Med. Virol., 92:
464-467. DOI: 10.1002/jmv.25702
Zhao, J., Q. Yuan, H. Wang, W. Liu and X. Liao et al.,
2020. Antibody responses to SARS-CoV-2 in
patients of novel coronavirus disease 2019. Clin.
Infect. Dis. DOI: 10.1093/cid/ciaa344
Zhou, P., X.L. Yang, X.G. Wang, B. Hu and L. Zhang
et al., 2020. A pneumonia outbreak associated with
a new coronavirus of probable bat origin. Nature,
579: 270-273. DOI: 10.1038/s41586-020-2012-7
... . All samples were tested for viral antibody with a 2019-nCOV/COVID-19 IgG/IgM Rapid Test Device (Hangzhou Realy Tech Co., Ltd.)[4]. The sample studied is shown inFigure 1, 5% (83/1586) of the analysed subjects resulted in SARS-CoV-2 virus infected, while 95% (1503/1586) had no positive results for the serological test(Table 1). ...
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The outbreak of the novel coronavirus disease (COVID‐19) quickly spread all over China and to more than 20 other countries. Although the virus (SARS‐Cov‐2) nucleic acid RT‐PCR test has become the standard method for diagnosis of SARS‐CoV‐2 infection, these real‐time PCR test kits have many limitations. In addition, high false negative rates were reported. There is an urgent need for an accurate and rapid test method to quickly identify large number of infected patients and asymptomatic carriers to prevent virus transmission and assure timely treatment of patients. We have developed a rapid and simple point‐of‐care lateral flow immunoassay which can detect IgM and IgG antibodies simultaneously against SARS‐CoV‐2 virus in human blood within 15 minutes which can detect patients at different infection stages. With this test kit, we carried out clinical studies to validate its clinical efficacy uses. The clinical detection sensitivity and specificity of this test were measured using blood samples collected from 397 PCR confirmed COVID‐19 patients and 128 negative patients at 8 different clinical sites. The overall testing sensitivity was 88.66% and specificity was 90.63%. In addition, we evaluated clinical diagnosis results obtained from different types of venous and fingerstick blood samples. The results indicated great detection consistency among samples from fingerstick blood, serum and plasma of venous blood. The IgM‐IgG combined assay has better utility and sensitivity compared with a single IgM or IgG test. It can be used for the rapid screening of SARS‐CoV‐2 carriers, symptomatic or asymptomatic, in hospitals, clinics, and test laboratories. This article is protected by copyright. All rights reserved.
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Since the SARS outbreak 18 years ago, a large number of severe acute respiratory syndrome-related coronaviruses (SARSr-CoV) have been discovered in their natural reservoir host, bats1–4. Previous studies indicated that some of those bat SARSr-CoVs have the potential to infect humans5–7. Here we report the identification and characterization of a novel coronavirus (2019-nCoV) which caused an epidemic of acute respiratory syndrome in humans in Wuhan, China. The epidemic, which started from 12 December 2019, has caused 2,050 laboratory-confirmed infections with 56 fatal cases by 26 January 2020. Full-length genome sequences were obtained from five patients at the early stage of the outbreak. They are almost identical to each other and share 79.5% sequence identify to SARS-CoV. Furthermore, it was found that 2019-nCoV is 96% identical at the whole-genome level to a bat coronavirus. The pairwise protein sequence analysis of seven conserved non-structural proteins show that this virus belongs to the species of SARSr-CoV. The 2019-nCoV virus was then isolated from the bronchoalveolar lavage fluid of a critically ill patient, which can be neutralized by sera from several patients. Importantly, we have confirmed that this novel CoV uses the same cell entry receptor, ACE2, as SARS-CoV.
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Emerging infectious diseases, such as SARS and Zika, present a major threat to public health1–3. Despite intense research efforts, how, when and where new diseases appear are still the source of considerable uncertainly. A severe respiratory disease was recently reported in the city Wuhan, Hubei province, China. Up to 25th of January 2020, at least 1,975 cases have been reported since the first patient was hospitalized on the 12th of December 2019. Epidemiological investigation suggested that the outbreak was associated with a seafood market in Wuhan. We studied one patient who was a worker at the market, and who was admitted to Wuhan Central Hospital on 26th of December 2019 experiencing a severe respiratory syndrome including fever, dizziness and cough. Metagenomic RNA sequencing4 of a bronchoalveolar lavage fluid sample identified a novel RNA virus from the family Coronaviridae, designed here as WH-Human-1 coronavirus. Phylogenetic analysis of the complete viral genome (29,903 nucleotides) revealed that the virus was most closely related (89.1% nucleotide similarity) to a group of SARS-like coronaviruses (genus Betacoronavirus, subgenus Sarbecovirus) previously sampled from bats in China. This outbreak highlights the ongoing capacity of viral spill-over from animals to cause severe disease in humans.
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Background: A novel coronavirus of zoonotic origin (2019-nCoV) has recently been identified in patients with acute respiratory disease. This virus is genetically similar to SARS coronavirus and bat SARS-like coronaviruses. The outbreak was initially detected in Wuhan, a major city of China, but has subsequently been detected in other provinces of China. Travel-associated cases have also been reported in a few other countries. Outbreaks in health care workers indicate human-to-human transmission. Molecular tests for rapid detection of this virus are urgently needed for early identification of infected patients. Methods: We developed two 1-step quantitative real-time reverse-transcription PCR assays to detect two different regions (ORF1b and N) of the viral genome. The primer and probe sets were designed to react with this novel coronavirus and its closely related viruses, such as SARS coronavirus. These assays were evaluated using a panel of positive and negative controls. In addition, respiratory specimens from two 2019-nCoV-infected patients were tested. Results: Using RNA extracted from cells infected by SARS coronavirus as a positive control, these assays were shown to have a dynamic range of at least seven orders of magnitude (2x10-4-2000 TCID50/reaction). Using DNA plasmids as positive standards, the detection limits of these assays were found to be below 10 copies per reaction. All negative control samples were negative in the assays. Samples from two 2019-nCoV-infected patients were positive in the tests. Conclusions: The established assays can achieve a rapid detection of 2019n-CoV in human samples, thereby allowing early identification of patients.