Evaluation of seven SARS-CoV-2 rapid IgM/IgG tests

RESUMEN Introducción: A finales de 2019, se detectó un nuevo coronavirus en China que provocó una enfermedad respiratoria aguda conocida como COVID-2019. Objetivo: Evaluar siete sistemas comerciales para la detección rápida de anticuerpos para determinar su sensibilidad, especificidad y robustez en nuestras condiciones para ser utilizados por el Sistema Nacional de Salud. Métodos: Se evaluaron siete sistemas para la detección de anticuerpos IgM/IgG. Se conformó un panel de evaluación con muestras de individuos negativos, sueros de otras afecciones previas a la pandemia y de pacientes positivos con la enfermedad. Resultados: Las cifras de sensibilidad general oscilan entre el 25 % y el 88 %, siendo los sistemas Realy Tech y Deep Blue los que mostraron los mejores resultados. La especificidad para ambos fue del 100 %. La tasa de IgM positiva según Realy Tech o Deep Blue aumentó a 94,1 % o 81,8 % en la etapa tardía de la enfermedad. Conclusiones: Los sistemas Realy Tech y Deep Blue detectaron IgM/IgG en suero y en sangre total con adecuada sensibilidad y especificidad. La reactividad cruzada no parece ser un problema. La serología en el caso de COVID-19 no puede utilizarse como diagnóstico pero permite a la vigilancia epidemiológica conocer el estado inmunológico de las poblaciones. Es fundamental analizar la respuesta inmune frente a la infección para realizar la caracterización epidemiológica y potencialmente informar el riesgo individual de futuras enfermedades y el estudio de posibles vacunas.

ABSTRACT Introduction: In late 2019, a new coronavirus was detected in China causing an acute respiratory illness known as COVID-2019. Objective: Evaluate seven commercial systems for the rapid detection of antibodies to determine their sensitivity, specificity and robustness in our conditions to be used by the National Health System. Methods: Seven systems were evaluated for the detection of IgM/IgG antibodies. Evaluation panel with samples from negative individuals, sera from other pathologies prior to the pandemic and from positive patients with the disease were conformed. Results: General sensitivity figures range between 25 and 88%, with the Realy Tech and Deep Blue systems showed the best results. The specificity for both was 100%. The IgM positive rate according to Realy Tech or Deep Blue increased to 94.1 or 81.8% in the late stage of the disease. Conclusions: Realy Tech and Deep Blue systems detected IgM/IgG in serum and in whole blood with adequate sensitivity and specificity. Cross-reactivity does not seem to be a problem. Serology in the case of COVID-19 cannot be used as a diagnostic but it allows epidemiological surveillance to know the immune status of populations. It's essential to analyze the immune response against the infection to carry out epidemiological characterization and potentially inform individual risk of future disease and the study of potential vaccines.

Challenges To The Management Of Psychiatric Hospitals Caused By The Continued Positive Antibodies Of Patients With Schizophrenia After Covid-19: Two Case Reports

@#In the context of the global pandemic of COVID-19, with the epidemic epicenter located in the Wuhan City, China, patients with severe mental illness have also been deeply affected by the epidemic. In this paper, two patients with schizophrenia who recovered from COVID-19 were reported. Because of the long-term positive results of the SARS-CoV-2 serum antibody IgM test, they had to undergo medical isolation and social restrictions for a long time. After the situation was effectively identified by the medical staff and they were eliminated as a potential virus carrier and released from the medical isolation center. Since psychiatrists often lack systematic knowledge of infectious diseases, the authors hope that this paper can provide a reference to avoid unnecessary wastage of medical resources and prevent placing serious mental burden on such patients in the future.

Detection of antibodies against SARS-CoV-2 as a serologic marker of infection in patients with COVID-19 / 中国输血杂志

【Objective】 To investigate the diagnostic value of severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) specific antibodies IgM and IgG on coronavirus disease 2019 (COVID-19). 【Methods】 1) The test results of SARS-CoV-2 IgM/IgG antibodies and nucleic acid(NAT), which were tested by colloidal gold test and fluorescent quantitative PCR respectively, were collected from 145 febrile outpatients during early March, 2020, named Fever group, in which retrospective analysis and paired chi-square test were performed. 2) 612 cases of SARS-CoV-2 IgM/IgG antibodies test results, which were done on March 5, 2020, were collected. They were named COVID-19 group (Our hospital was provisionally assigned as a specialized hospital for COVID-19, and 1500 COVID-19 patients admitted to our hospital from February 12, 2020 to March 18, 2020). The SARS-CoV-2 IgM/IgG antibodies and NAT were respectively tested on the 30th and the 60th day after the date of discharge. The clinical application values of the antibodies was clarified by statistical analysis. 【Results】 1) In the fever group, the positive rate of SARS-CoV-2 IgM, IgG and IgM+ IgG antibodies were 26.21% (38/145), 54.48% (79/145) and 26.21% (38/145), respectively(P<0.01), and the positive rate of NAT was 4.14% (6/145), which was lower than that of antibody (P<0.01). One (1/145, 0.69%) positive NAT was implicated in initially negative IgM and IgG antibodies samples. 2) In the COVID-19 group, the positive rate of IgM antibody was low (5%) and IgG antibody was high (65%) during 2~14 days after infection, and stably increased during the 15~56 days [IgM 47.68%(277/581) vs IgG 94.15% (547/581) ], then both decreased after 57 days. The positive rates of IgM antibody and IgG antibody were 45.8% (280/612) and 93.1% (570/612) in 612 patients during hospitalization. 15 patients′ data after dischange were not collected as they were later transferred to Huoshenshan Hospital for treatment. The coronavirus NAT results of the rest 597 COVID-19 patients, tested on the 30th and 60th days after the date of discharge, were negative, and the positive rates of IgG antibody and IgM antibody were still ≥80% and ≥40% respectively at the second month after discharge. 【Conclusion】 IgM, IgG antibody against SARS-CoV-2 can be well detected by Colloidal gold method(Innovita), whose positive rate is higher than that of NAT. IgG antibody is produced earlier than IgM, and it keeps high positive rate and persists for a long time. The combination of colloidal gold antibody test and NAT can improve the diagnose rate of COVID-19 and the exclusion of suspected cases.

Pre-evaluation assessment of serological-based COVID-19 point-of-care lateral flow assays in Kenya

Background: Timely testing is a key determinant of management outcomes of coronavirus disease 2019 (COVID-19). Real-time reverse transcription polymerase chain reaction tests are currently the mainstay for COVID-19 testing. However, serological point-of-care tests (PoCTs) can be useful in identifying asymptomatic and recovered cases, as well as herd immunity. Objective: The aim of this study was to assess COVID-19 PoCTs in Kenya to support the emergency use authorisation of these tests. Methods: Between March 2020 and May 2020, 18 firms, of which 13 were from China, submitted their PoCTs to the national regulatory authority, the Pharmacy and Poison Board, who in turn forwarded them to the Kenya Medical Research Institute for pre-evaluation assessment. The tests were run with real-time reverse transcription polymerase chain reaction COVID-19-positive samples. Pre-COVID-19 plasma samples that were collected in June 2019were used as negative samples. The shelf lives of the PoCTs ranged from 6 to 24 months. Results: Only nine (50%) tests had sensitivities ≥ 40% (range: 40% ­ 60%) and the ability of these tests to detect IgM ranged from 0% to 50%. Many (7/18; 38.9%) of the kits had very weak IgM and IgG band intensities (range: 2­3). Conclusion: Serological-based PoCTs available in Kenya can only detect COVID-19 in up to 60% of the infected population.

Kinetics of viral RNA, immunoglobulin-M & G antibodies in Kyasanur forest disease

Background & objectives: Kyasanur forest disease (KFD) is an infectious disease discovered in Karnataka State of India in 1957; since then, the State has been known to be enzootic for KFD. In the last few years, its presence was observed in the adjoining five States of the Western Ghats of India. The present study was conducted to understand the kinetics of viral RNA, immunoglobulin M (IgM) and IgG antibody in KFD-infected humans for developing a diagnostic algorithm for KFD. Methods: A prospective follow up study was performed among KFD patients in Sindhudurg district of Maharashtra State, India. A total of 1046 suspected patients were tested, and 72 KFD patients were enrolled and followed for 17 months (January 2016 to May 2017). Serum samples of KFD patients were screened for viral RNA, and IgM and IgG antibodies. Results: KFD viral positivity was observed from 1st to 18th post-onset day (POD). Positivity of anti-KFD virus (KFDV) IgM antibodies was detected from 4th till 122nd POD and anti-KFDV IgG antibodies detected from 5th till 474th POD. A prediction probability was determined from statistical analysis using the generalized additive model in R-software to support the laboratory findings regarding viral kinetics. Interpretation & conclusions: This study demonstrated the presence of KFD viral RNA till 18th POD, IgM antibodies till 122nd POD and IgG till the last sample collected. Based on our study an algorithm was recommended for accurate laboratory diagnosis of KFDV infection. A sample collected between 1 and 3 POD can be tested using KFDV real-time reverse transcriptase polymerase chain reaction (RT-PCR); between 4 and 24 POD, the combination of real-time RT-PCR and anti-KFDV IgM enzyme-linked immunosorbent assay (ELISA) tests can be used; between POD 25 and 132, anti-KFDV IgM and IgG ELISA are recommended.

Detection methods of non-Gal xenoantibody in human serum / 器官移植

Objective To investigate the optimal condition for the detection of anti-non-galactose (Gal) xenoantigen and antibody in human serum.Mehtods Peripheral blood mononuclear cell (PBMC) obtained from Wuzhishan miniature pig models with α-1,3-galactosyltransferase gene knockout (GTKO) were used as target cells,mixed and incubated with healthy human serum of different concentrations (4.8％,16.7％ and 100％) for 0.5,1.0,2.0,3.0 and 6.0 h,respectively.The abilities of PBMC to bind with IgM and IgG were detected by flow cytometry.Results At the serum concentration of 16.7％,the ability ofnon-Gal IgM to bind with PBMC was significantly enhanced from 0.5 h to 3.0 h incubation (P＜0.01),whereas no statistical significance was noted in terms of IgG (P＞0.05).Increasing serum concentration could also enhance the ability of non-Gal IgM to bind with PBMC.At the serum concentration of 100％ and incubation for 3 h,the ability of IgM to bind with PBMC was the highest among all groups (P＜0.01).At the serum concentration of 100％ and incubation for 6 h,the ability of IgG to bind with PBMC was significantly enhanced (P＜0.05).Prolonging incubation time and increasing serum concentration did not affect the activity of PBMC.Conclusions The optimal condition for detection of anti-non-Gal xenoantigen and antibody is determined.A quantity of 1×105 PBMC from pig should be incubated with 100％ human serum for 3 h for detection of IgM level,or incubated with 100％ human serum for 6 h for measurement of IgG level.This optimized condition contributes to screening the donor pigs which lowly express non-Gal antigen.

Detection of NS1 antigen, IgM antibody for the diagnosis of dengue infection in patients with acute febrile illness.

Background: Dengue is an endemic viral disease affecting tropical and subtropical regions around the world. Infection with any 1 of 4 dengue viruses produces with spectrum of clinical illness ranging from a mild undifferentiated febrile illness to dengue fever (DF) to dengue haemorrhagic fever (DHF), a potentially life threatening disease. The mortality and morbidity of DHF can be reduced by early diagnosis, hospitalisation and careful supportive care. Detection of non-structural antigen (NS1 Ag), IgM and IgG antibody may help in the early diagnosis. Methods: The present study was taken from the Pt J N M Medical College, Raipur (CG.) department of Microbiology. The one year study from August 2014 to July 2015 detection of NS1 Ag and IgM antibody. Elisa were tested a penal compared of 1637 serum specimens collected from acute febrile patients. Out of 1637 patients 538_were found to have acute dengue infection by detection of NS1Ag and anti-dengue IgM Elisa. Results: Out of 1637 patients 538- were found to acute dengue infection. Out of 538– NS1 161—IgM 294 positive. Males are more affected than females and 21 to 30 year age group were more infected. Dengue illness were more in rainy and post rainy season. Conclusions: The present study showed that dengue serological tests have a significant role in the early diagnosis of dengue fever, Hence, it is recommended to do the serological tests (NS1 Ag, IgM, IgG Ab) early in all suspected dengue cases so that, we can diagnosis early and initiate necessary treatment.

The Usefulness of PCR and Early Antigen Immunostaining as a Rapid Identification Method of Cytomegalovirus Infection / 대한임상병리학회지

BACKGROUND: Cytomegalovirus infection is an important cause of morbidity and mortality after organ transplantation. Thus, rapid, sensitive and specific laboratory test, such as CMV antigenemia assay and polymerase chain reaction (PCR) is necessary to determine a patient's risk of CMV disease and to monitor the effectiveness of antiviral therapy. We compared the results of CMV-PCR and CMV early antigen immunostaining (CMV-EA) with CMV-specific IgM antibody to evalutate clinical usefulness for the early diagnosis of CMV infection and monitoring of antiviral therapy. METHODS: We analyzed 170 samples submitted for CMV tests between September 1995 and April 1996 in Yonsei University College of Medicine Severance Hospital. CMV-PCR and CMV-EA were performed with buffy coat cells and detection of CMV-specific IgM antibody was performed by enzyme-linked fluorescent assay (ELFA). RESULTS: One hundred and seventy samples of 159 patients were tested and analyzed. The concordance rate of CMV-PCR, CMV-EA and CMV-specific IgM in the same blood sample was 75.3%. The total incidence of CMV disease was 2.5%. The sensitivity and specificity based on the patients' clinical status of PCR were 100% and 91.6% respectively. In CMV-EA immunostaining method, they were 75.0% and 100% respectively. And, for CMV-specific IgM antibody ELFA, the sensitivity was only 50.0% and the specificity was 96.4%. CONCLUSIONS: CMV-PCR and CMV-EA immunostaining are reliable methods as rapid early detection of CMV infection. The sensitivity and specificity are very high comparing to CMV- specific IgM antibody. It could also be concluded that they have advantages not only for early diagnosis but also monitoring or follow-up of a therapeutic course as quantitative assays.