ABSTRACT
Shortages of reverse transcriptase (RT)-polymerase chain reaction (PCR) reagents and related equipment during the COVID-19 pandemic have demonstrated the need for alternative, high-throughput methods for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-mass screening in clinical diagnostic laboratories. A robust, SARS-CoV-2 RT-loop-mediated isothermal amplification (RT-LAMP) assay with high-throughput and short turnaround times in a clinical laboratory setting was established and compared to two conventional RT-PCR protocols using 323 samples of individuals with suspected SARS-CoV-2 infection. Limit of detection (LoD) and reproducibility of the isolation-free SARS-CoV-2 RT-LAMP test were determined. An almost perfect agreement (Cohen's kappa > 0.8) between the novel test and two classical RT-PCR protocols with no systematic difference (McNemar's test, P > 0.05) was observed. Sensitivity and specificity were in the range of 89.5 to 100% and 96.2 to 100% dependent on the reaction condition and the RT-PCR method used as reference. The isolation-free RT-LAMP assay showed high reproducibility (Tt intra-run coefficient of variation [CV] = 0.4%, Tt inter-run CV = 2.1%) with a LoD of 95 SARS-CoV-2 genome copies per reaction. The established SARS-CoV-2 RT-LAMP assay is a flexible and efficient alternative to conventional RT-PCR protocols, suitable for SARS-CoV-2 mass screening using existing laboratory infrastructure in clinical diagnostic laboratories.
Subject(s)
COVID-19 Nucleic Acid Testing/methods , COVID-19/diagnosis , COVID-19/epidemiology , Molecular Diagnostic Techniques/methods , Nucleic Acid Amplification Techniques/methods , Pandemics , Reverse Transcriptase Polymerase Chain Reaction/methods , SARS-CoV-2/genetics , COVID-19/virology , Genome, Viral , Humans , Infection Control/methods , Limit of Detection , Mass Screening/methods , RNA, Viral/genetics , RNA, Viral/isolation & purification , RNA-Directed DNA Polymerase/genetics , Reproducibility of Results , Reverse Transcription/genetics , Sensitivity and SpecificityABSTRACT
To study host-virus interactions after SARS coronavirus-2 (SARS-CoV-2) infection, genetic virus characteristics and the ensued humoral immune response were investigated for the first time. Fifty-five SARS-CoV-2-infected patients from the early pandemic phase were followed up including serological testing and whole genome sequencing. Anti-spike and nucleocapsid protein (S/N) IgG and IgM levels were determined by screening ELISA and IgG was further characterized by reactivity to S-subunit 1 (anti-S1), S-subunit 2 (anti-S2) and anti-N. In 55 patients, 90 genetic SARS-CoV-2 changes including 48 non-synonymous single nucleotide variants were identified. Phylogenetic analysis of the sequencing data showed a cluster representing a local outbreak and various family clusters. Anti-S/N and anti-N IgG were detected in 49 patients at an average of 83 days after blood collection. Anti-S/N IgM occurred significantly less frequently than IgG whereas anti-S2 was the least prevalent IgG reactivity (P < 0.05, respectively). Age and overweight were significantly associated with higher anti-S/N and anti-S1 IgG levels while age only with anti-N IgG (multiple regression, P < 0.05, respectively). Anti-S/N IgG/IgM levels, blood group A + , cardiovascular and tumour disease, NSP12 Q444H and ORF3a S177I were independent predictors of clinical characteristics with anti-S/N IgM being associated with the need for hospitalization (multivariate regression, P < 0.05, respectively). Anti-SARS-CoV-2 antibody generation was mainly affected by higher age and overweight in the present cohort. COVID-19 traits were associated with genetic SARS-CoV-2 variants, anti-S/N IgG/IgM levels, blood group A + and concomitant disease. Anti-S/N IgM was the only antibody associated with the need for hospitalization.
Subject(s)
COVID-19 , Antibodies, Viral , Humans , Immunoglobulin G , Immunoglobulin M , Phylogeny , SARS-CoV-2 , Spike Glycoprotein, CoronavirusABSTRACT
Severe acute respiratory syndrome coronavirus 2 infection and development of coronavirus disease 2019 presents a major health care challenge of global dimensions. Laboratory diagnostics of infected patients, and the assessment of immunity against severe acute respiratory syndrome coronavirus 2, presents a major cornerstone in handling the pandemic. Currently, there is an increase in demand for antibody testing and a large number of tests are already marketed or are in the late stage of development. However, the interpretation of test results depends on many variables and factors, including sensitivity, specificity, potential cross-reactivity and cross-protectivity, the diagnostic value of antibodies of different isotypes, and the use of antibody testing in identification of acutely ill patients or in epidemiological settings. In this article, the recently established COVID-19 Task Force of the German Society for Clinical Chemistry and Laboratory Medicine (DGKL) addresses these issues on the basis of currently available data sets in this rapidly moving field.