1. False-positive results of SARS-CoV-2 IgM/IgG antibody tests in sera stored before the 2020 pandemic in Italy
- Author
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Giuseppe Corritore, Nicola Andriulli, Anna Latiano, R. Fontana, Giuseppe Miscio, Grazia Anna Niro, Domenica Gioffreda, Fabrizio Bossa, Orazio Palmieri, Giuseppe Biscaglia, Francesca Tavano, Tiziana Latiano, Massimo Carella, Annamaria Gentile, Anna Panza, Lazzaro Di Mauro, and Maria Guerra
- Subjects
Adult ,Male ,0301 basic medicine ,Microbiology (medical) ,Adolescent ,Coronavirus disease 2019 (COVID-19) ,Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ,030106 microbiology ,Enzyme-Linked Immunosorbent Assay ,Antibodies, Viral ,Article ,Immunoglobulin G ,Virus ,COVID-19 Serological Testing ,lcsh:Infectious and parasitic diseases ,Serology ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,mental disorders ,Humans ,Medicine ,False Positive Reactions ,lcsh:RC109-216 ,030212 general & internal medicine ,Pandemics ,Aged ,Retrospective Studies ,Aged, 80 and over ,biology ,SARS-CoV-2 ,Serological tests ,business.industry ,COVID-19 ,Outbreak ,General Medicine ,Middle Aged ,Virology ,Infectious Diseases ,Immunoglobulin M ,Italy ,biology.protein ,Female ,Antibody ,IgM/IgG antibodies ,business - Abstract
Objectives: Aside from the outbreak of the coronavirus disease 2019 (COVID-19), serological tests are not well known for their diagnostic value. We assessed the performance of serological tests using stored sera from patients with a variety of pathologic conditions, collected before the 2020 pandemic in Italy. Methods: Rapid lateral flow tests and Enzyme-Linked Immunosorbent Assays (ELISA) that detect Immunoglobulin M (IgM) and Immunoglobulin G (IgG) antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were carried out using 1150 stored human serum samples that had been collected in 2018 and 2019. The tests were also run using samples from 15 control patients who had positive or negative oral swab test results, as assessed using real-time reverse transcription-polymerase chain reaction (rRT-PCR). The urea dissociation test was employed to rule out false-positive reactivity in the two antibody detection methods. Results: The lateral flow tests revealed 21 positive samples from the stored sera: 12 for IgM, four for IgG, and five for IgM/IgG. Among the nine rRT-PCR- positive controls, six individuals presented IgG and three IgM/IgG positivity. Using the urea (6 mol/L) dissociation test, two of the twelve stored samples that had shown IgM positivity were confirmed to be positive. The ELISA test detected four IgM-positive and three IgG-positive specimens. After treatment with 4 mol/L urea, the IgM-positive samples became negative, whereas the IgG positivity persisted. All of the rRT-PCR-positive controls were found to retain IgM or IgG positivity following the urea treatment. Conclusions: Our findings highlight the limited utility of serological testing for the SARS-CoV-2 virus based on the results of specimens collected before the outbreak of the infection.
- Published
- 2021
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