This study presents a graphene field-effect transistor (gFET) biosensor with dual detection capabilities for SARS-CoV-2: one RNA detection assay to confirm viral positivity and the other for nucleocapsid (N-)protein detection as a proxy for infectiousness of the patient. This technology can be rapidly adapted to emerging infectious diseases, making an essential tool to contain future pandemics. To detect viral RNA, the highly conserved E-gene of the virus was targeted, allowing for the determination of SARS-CoV-2 presence or absence using nasopharyngeal swab samples. For N-protein detection, specific antibodies were used. Tested on 213 clinical nasopharyngeal samples, the gFET biosensor showed good correlation with RT-PCR cycle threshold values, proving its high sensitivity in detecting SARS-CoV-2 RNA. Specificity was confirmed using 21 pre-pandemic samples positive for other respiratory viruses. The gFET biosensor had a limit of detection (LOD) for N-protein of 0.9 pM, establishing a foundation for the development of a sensitive tool for monitoring active viral infection. Results of gFET based N-protein detection corresponded to the results of virus culture in all 16 available clinical samples and thus it also proved its capability to serve as a proxy for infectivity. Overall, these findings support the potential of the gFET biosensor as a point-of-care device for rapid diagnosis of SARS-CoV-2 infection and indirect assessment of infectiousness in patients, providing additional information for clinical and public health decision-making.
- MeSH
- biosenzitivní techniky * přístrojové vybavení metody MeSH
- COVID-19 * diagnóza virologie MeSH
- design vybavení MeSH
- elektronické tranzistory MeSH
- fosfoproteiny MeSH
- grafit * chemie MeSH
- koronavirové nukleokapsidové proteiny izolace a purifikace MeSH
- lidé MeSH
- limita detekce MeSH
- nazofarynx virologie MeSH
- RNA virová * izolace a purifikace analýza MeSH
- SARS-CoV-2 * izolace a purifikace genetika MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Secretory (S) IgA antibodies against severe acute respiratory syndrome (SARS)-CoV-2 are induced in saliva and upper respiratory tract (URT) secretions by natural infection and may be critical in determining the outcome of initial infection. Secretory IgA1 (SIgA1) is the predominant isotype of antibodies in these secretions. Neutralization of SARS-CoV-2 is most effectively accomplished by polymeric antibodies such as SIgA. We hypothesize that cleavage of SIgA1 antibodies against SARS-CoV-2 by unique bacterial IgA1 proteases to univalent Fabα antibody fragments with diminished virus neutralizing activity would facilitate the descent of the virus into the lungs to cause serious disease and also enhance its airborne transmission to others. Recent studies of the nasopharyngeal microbiota of patients with SARS-CoV-2 infection have revealed significant increases in the proportions of IgA1 protease-producing bacteria in comparison with healthy subjects. Similar considerations might apply also to other respiratory viral infections including influenza, possibly explaining the original attribution of influenza to Haemophilus influenzae, which produces IgA1 protease.
- MeSH
- Bacteria enzymologie MeSH
- COVID-19 * přenos imunologie virologie mikrobiologie MeSH
- Haemophilus influenzae enzymologie imunologie MeSH
- imunoglobulin A sekreční * metabolismus MeSH
- imunoglobulin A imunologie MeSH
- lidé MeSH
- nazofarynx mikrobiologie virologie MeSH
- neutralizující protilátky imunologie MeSH
- protilátky virové imunologie MeSH
- SARS-CoV-2 * imunologie MeSH
- serinové endopeptidasy metabolismus imunologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Testing of pooled samples is an effective strategy for increasing testing capacity while saving resources and time. This study aimed to validate pooled testing and gather real-life data on its use for Covid-19 surveillance with a gargle lavage (GL) self-sampling strategy. METHODS: Two-stage pooled testing with pools of 6 and 12 samples was used for preventive testing of an asymptomatic population and Covid-19 surveillance in Czech schools. Both GL and nasopharyngeal swabs were used for sampling. RESULTS: In total, 61,111 samples were tested. The use of pooled testing for large-scale Covid-19 surveillance reduced consumable costs by almost 75% and increased testing capacity up to 3.8-fold compared to standard methods. RT-PCR experiments revealed a minimal loss of sensitivity (0-2.2%) when using pooled samples, enabling the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genes with Ct values >35. The minor loss of sensitivity was counterbalanced by a significantly increased throughput and the ability to substantially increase testing frequencies. CONCLUSIONS: Pooled testing is considerably more cost-effective and less time-consuming than standard testing for large-scale Covid-19 surveillance even when the prevalence of SARS-CoV-2 is fluctuating. Gargle lavage self-sampling is a non-invasive technique suitable for sample collection without a healthcare worker's assistance.
- MeSH
- COVID-19 * diagnóza epidemiologie MeSH
- lidé MeSH
- nazofarynx * virologie MeSH
- odběr biologického vzorku * metody MeSH
- SARS-CoV-2 * genetika izolace a purifikace MeSH
- senzitivita a specificita MeSH
- testování na COVID-19 průkazem nukleové kyseliny metody MeSH
- testování na COVID-19 metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
- MeSH
- chybná diagnóza MeSH
- COVID-19 diagnóza virologie MeSH
- indikátory a reagencie chemie MeSH
- lidé MeSH
- limita detekce MeSH
- nazofarynx virologie MeSH
- odběr biologického vzorku normy MeSH
- polymerázová řetězová reakce s reverzní transkripcí MeSH
- RNA virová genetika metabolismus MeSH
- SARS-CoV-2 genetika izolace a purifikace MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
