Shedding of Viable Virus in Asymptomatic SARS-CoV-2 Carriers (original) (raw)
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Clinical Microbiology and Infection, 2021
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Scientific Reports
The COVID-19 pandemic requires sensitive detection of the SARS-CoV-2 virus from samples to ensure accurate detection of infected patients, an essential component of effective national track and trace programs. Due to the scaling challenges of large sample numbers, sample pooling is an attractive solution to reduce both extraction and amplification reagent costs, if high sensitivity can be maintained. We demonstrate that the Erba Molecular ErbaMDx SARS-CoV-2 RT-PCR Kit (EM kit) delivers high sensitivity, achieving analytical detection of 5 copies/reaction SARS-CoV-2 genomic RNA, and 200 copies/mL SARS-CoV-2 inactivated virus spiked into nasopharyngeal swab (NP) samples and extracted through workflow. Furthermore, the EM Kit demonstrates high sensitivity in both pooled (1 in 5) and non-pooled NP samples when compared to an FDA Emergency Use Authorization approved assay, following published FDA guidelines. These findings demonstrate that the EM Kit is suitable for sample pooling, with ...
Advanced Molecular and Immunological Diagnostic Methods to Detect SARS-CoV-2 Infection
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COVID-19 emerged in late 2019 in China and quickly spread across the globe, causing over 521 million cases of infection and 6.26 million deaths to date. After 2 years, numerous advances have been made. First of all, the preventive vaccine, which has been implemented in record time, is effective in more than 95% of cases. Additionally, in the diagnostic field, there are numerous molecular and antigenic diagnostic kits that are equipped with high sensitivity and specificity. Real Time-PCR-based assays for the detection of viral RNA are currently considered the gold-standard method for SARS-CoV-2 diagnosis and can be used efficiently on pooled nasopharyngeal, or oropharyngeal samples for widespread screening. Moreover, additional, and more advanced molecular methods such as droplet-digital PCR (ddPCR), clustered regularly interspaced short palindromic repeats (CRISPR) and next-generation sequencing (NGS), are currently under development to detect the SARS-CoV-2 RNA. However, as the num...
2022
SARS-CoV-2 transmission occurs even among fully vaccinated individuals; thus, prompt identification of infected patients is central to control viral circulation. Antigen rapid diagnostic tests (Ag-RDT) are highly specific, but sensitivity is variable.Discordant RT-qPCR vs Ag-RDT results are reported, raising the question of whether negative Ag-RDT in positive RT-qPCR samples could imply the absence of infectious viruses. To study the relationship between a negative Ag-RDT results with virological, molecular, and serological parameters, we selected a cross sectional and a follow-up dataset and analyzed virus culture, subgenomic RNA quantification, and sequencing to determine infectious viruses and mutations. We demonstrated that a positive SARS-CoV-2 Ag-RDT result correlates with the presence of infectious virus in nasopharyngeal samples. A decrease in sgRNA detection together with an expected increase in detectable anti-S and anti-N IgGs was verified in negative Ag-RDT / positive RT...
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The mechanisms that allowed for the SARS-CoV-2 B.1.1.7 variant to rapidly outcompete pre-existing variants in many countries remain poorly characterized. Here, we analyzed viral release, anti-SARS-CoV-2 antibodies and cytokine production in a retrospective series of 427 RT–qPCR+ nasopharyngeal swabs collected in COVID-19 patients harbouring either non-B.1.1.7 or B.1.17 variants. We utilized a novel rapid assay, based on S-Fuse-T reporter cells, to quantify infectious SARS-CoV-2. With both non-B.1.1.7 and B.1.1.7 variants, viral titers were highly variable, ranging from 0 to >106 infectious units, and correlated with viral RNA levels. Lateral flow antigenic rapid diagnostic tests (RDTs) were positive in 96% of the samples harbouring infectious virus. About 67 % of individuals carried detectable infectious virus within the first two days after onset of symptoms. This proportion decreased overtime, and viable virus was detected up to 14 days. Samples containing anti-SARS-CoV-2 IgG o...