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J Infect Dis ; 225(6): 965-970, 2022 03 15.
Article in English | MEDLINE | ID: covidwho-1740882


Antibody responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in serum and cerebrospinal fluid (CSF) samples from 16 patients with coronavirus disease 2019 and neurological symptoms were assessed using 2 independent methods. Immunoglobulin G (IgG) specific for the virus spike protein was found in 81% of patients in serum and in 56% in CSF. SARS-CoV-2 IgG in CSF was observed in 2 patients with negative serological findings. Levels of IgG in both serum and CSF were associated with disease severity (P < .05). All patients with elevated markers of central nervous system damage in CSF also had CSF antibodies (P = .002), and CSF antibodies had the highest predictive value for neuronal damage markers of all tested clinical variables.

Antibodies, Viral/blood , COVID-19/diagnosis , Immunoglobulin G/blood , Nervous System Diseases/blood , Nervous System Diseases/cerebrospinal fluid , SARS-CoV-2/isolation & purification , Aged , Antibodies, Neutralizing/blood , Antibody Formation , Biomarkers/blood , Biomarkers/cerebrospinal fluid , COVID-19/blood , COVID-19/cerebrospinal fluid , COVID-19/complications , Female , Humans , Male , Middle Aged , Nervous System Diseases/diagnosis , Nervous System Diseases/etiology , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus
Viruses ; 13(6)2021 05 31.
Article in English | MEDLINE | ID: covidwho-1256670


The potential of rapid point-of-care (POC) tests has been subject of doubt due to an eventual risk of production errors. The aim was therefore to evaluate the two separate production lots of a commercial POC lateral flow test, intended for the detection of IgM and IgG against the SARS-CoV-2 spike protein (S1). Control samples consisted of serum from individuals with confirmed SARS-CoV-2 infection and pre-COVID-19 negative sera gathered from a biobank. The presence of anti-S1 IgM/IgG in the sera was verified by an in-house Luminex-based serological assay (COVID-19 SIA). One hundred samples were verified as positive for anti-S1 IgG and 74 for anti-S1 IgM. Two hundred samples were verified as negative for anti-S1 IgM/IgG. For the two lots of the POC-test, the sensitivities were 93.2% and 87.8% for IgM and 93.0% and 100% for IgG. The specificities were 100% for IgM and 99.5% for IgG. The positive predictive value was 100% for IgM and 98.9% and 99.0% for IgG. The negative predictive value was 97.6% and 95.7% for IgM, and 96.6% and 100% for IgG. The evaluated POC-test is suitable to assess anti-SARS-CoV-2 S1 IgM and IgG, as a measure of previous virus exposure on an individual level. The external validation of separate lots of rapid POC-tests is encouraged to ensure high sensitivity before market introduction.

Antibodies, Viral/blood , COVID-19 Serological Testing/methods , COVID-19/diagnosis , Point-of-Care Testing , Spike Glycoprotein, Coronavirus/immunology , Antibodies, Viral/immunology , COVID-19/immunology , Humans , Immunoglobulin G/blood , Immunoglobulin G/immunology , Immunoglobulin M/blood , Immunoglobulin M/immunology , Sensitivity and Specificity
Viruses ; 13(6)2021 05 26.
Article in English | MEDLINE | ID: covidwho-1244150


Due to the current, rapidly increasing Coronavirus disease 2019 (COVID-19) pandemic, efficient and highly specific diagnostic methods are needed. The receptor-binding part of the spike (S) protein, S1, has been suggested to be highly virus-specific; it does not cross-react with antibodies against other coronaviruses. Three recombinant partial S proteins of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) expressed in mammalian or baculovirus-insect cells were evaluated as antigens in a Luminex-based suspension immunoassay (SIA). The best performing antigen (S1; amino acids 16-685) was selected and further evaluated by serum samples from 76 Swedish patients or convalescents with COVID-19 (previously PCR and/or serologically confirmed), 200 pre-COVID-19 individuals (180 blood donors and 20 infants), and 10 patients with acute Epstein-Barr virus infection. All 76 positive samples showed detectable antibodies to S1, while none of the 210 negative controls gave a false positive antibody reaction. We further compared the COVID-19 SIA with a commercially available enzyme immunoassay and a previously evaluated COVID-19 rapid antibody test. The results revealed an overall assay sensitivity of 100%, a specificity of 100% for both IgM and IgG, a quantitative ability at concentrations up to 25 BAU/mL, and a better performance as compared to the commercial assays, suggesting the COVID-19 SIA as a most valuable tool for efficient laboratory-based serology.

Antibodies, Viral/blood , COVID-19 Serological Testing/methods , COVID-19/diagnosis , Immunoassay/methods , SARS-CoV-2/immunology , COVID-19/immunology , Herpesvirus 4, Human/immunology , Humans , Immunoglobulin G/blood , Immunoglobulin G/immunology , Immunoglobulin M/blood , Immunoglobulin M/immunology , Reproducibility of Results , Sensitivity and Specificity , Spike Glycoprotein, Coronavirus/immunology