Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 6 de 6
Filter
1.
Talanta ; 253: 123978, 2022 Oct 04.
Article in English | MEDLINE | ID: covidwho-2061902

ABSTRACT

Recently, sensitive, fast and low cost nucleic acid isothermal amplification technologies (such as loop-mediated isothermal amplification, LAMP) have attracted great attention in the urgent needs of point-of-care testing (POCT) and regular epidemic prevention and control. However, unlike PCR which usually employs TaqMan probe to report specific signals, specific-signal-output strategies in isothermal amplification are immature and visual detection even rare, which limits their popularity in POCT. We hypothesize to address this issue by designing a visual-signal-report system to both filtrate and magnify the target information in isothermal amplification. In this work, we developed a specific signal filtration and magnification colorimetric isothermal sensing platform (SFMC for short) for ultrasensitive detection of DNA and RNA. SFMC consists of two processes: an isothermal amplification with specific signal filtration and a self-replication catalyzed hairpin assembly (SRCHA) for rapid target-specific signal magnification and outputting. With these unique properties, this biosensing platform could detect target DNA as low as 5 copies per reaction and target RNA as low as 10 copies per reaction by naked eyes. Benefited from the excellent colorimetric detection performance, this biosensing platform has been successfully used for African swine fever virus (ASFV) and SARS-CoV-2 detection.

2.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-315067

ABSTRACT

There have been several false-positive results in the antibody detection of the COVID-19. This study aims to analyze the distribution characteristics of SARS-CoV-2 IgM and IgG in false-positive results detected using chemiluminescent immunoassay. The characteristics of the false-positive results in SARS-CoV-2 IgM and IgG testing were retrospectively analyzed. The dynamic changes in the results of SARS-CoV-2 IgM and IgG antibodies were observed. The false-positive proportion of the single SARS-CoV-2 IgM positive results was 95.88%, which was significantly higher than those of the single SARS-CoV-2 IgG positive results (67.50%) ( P  < 0.001) and SARS-CoV-2 IgM & IgG positive results (29.55%) ( P  < 0.001). The S/CO of the SARS-CoV-2 IgM and IgG in false-positive results ranged from 1.0 to 50.0. The false-positive probability of SARS-CoV-2 IgM in the S/CO range (1.0 ~ 3.0) was 91.73% (77/84), and the probability of false-positive of SARS-CoV-2 IgG in the S/CO range (1.0 ~ 2.0) was 85.71% (24/28). Dynamic monitoring showed that the S/CO values of IgM in false-positive results decreased or remained unchanged, whereas the S/CO values of IgG in false-positive results only decreased. The possibility of false-positive of the single SARS-CoV-2 IgM positive and single SARS-CoV-2 IgG positive results was high. As the value of S/CO decreased, the probability of false-positive consequently increased, especially among the single SARS-CoV-2 IgM positive results.

3.
Chinese Journal of Virology ; 36(4):570-577, 2020.
Article in Chinese | GIM | ID: covidwho-1407616

ABSTRACT

We wished to explore the interference factors causing false-positive results for immunoglobulin M (IgM) and IgG antibodies in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detected by the gold immunochromatography assaym (GICA). In this way, we wanted to improve the detection method and scheme of laboratory detection. Seventy-four serum samples from outpatients and inpatients from the Affiliated Hospital of North Sichuan Medical College and Nanchong Central Hospital in China from 2 January 2020 to 5 March 2020 were collected 19 patients with the nucleic acids of SARS-CoV-2;10 cases with IgM antibodies against other respiratory viruses;10 patients with IgM antibodies against hepatitis viruses;20 patients with IgM antibodies against rheumatoid factor (RF);15 patients with antinuclear antibody (ANA). Colloidal GICA (kit A and kit B) was used to detect IgM and IgG antibodies against SARS-CoV-2 in patient sera. Positive results of SARS-CoV-2 IgM or SARS-CoV -2 IgG antibodies were analyzed, and possible factors causing false-positive results were found. Then, the sera of SARS- CoV - 2 IgM/IgG positive and 3 early coronavirus disease 2019 (COVID-19) patients were dissociated with an appropriate concentration of urea, and levels of IgM and IgG antibodies against SARS-CoV-2 were redetermined. SPSS v19.0 was used to analyze data. In the sera of 19 patients with SARS-CoV-2 infection 15 of SARS -CoV-2 IgM antibodies and 18 cases SARS-CoV-2 IgG antibodies were detected in kit A;12 cases of SARS-CoV-2 IgM antibodies and 12 cases of SARS-CoV-2 IgG antibodies were detected in kit B;16 cases of SARS-CoV-2 IgM antibodies and 14 cases of SARS-CoV -2 IgG antibodies were detected in 20 patients who had IgM antibodies against RF. In the sera of 15 patients with high - titer ANA, SARS-CoV- 2 IgG antibodies were detected in four cases using kit B. When the urea dissociation concentration was 2 mol/L, 14 of 16 RF- IgM - positive sera detected using kit A turned negative, 13 of 14 SARS- CoV- 2 IgG antibodies turned negative, but patients with COVID-19 detected by kit A did not show negative conversion of IgM or IgG antibodies. When the urea dissociation concentration was 4 mol/L, ANA -positive serum detected by kit B turned negative in four cases, whereas SARS-CoV-2 IgM and IgG antibodies in patients with COVID-19 did not turn negative. After urea dissociation, the SARS-CoV- 2 IgM antibodies detected by kit A and kit B in the sera of three patients with early COVID- 19 did not turn negative. RF could cause false-positive results for SARS-CoV-2 IgM and IgG antibodies detected by kit A, and a high titer of ANA could cause false-positive results of SARS-CoV-2 IgG antibodies detected by kit B. Urea dissociation could be helpful for reducing the probability of false-positive results of SARS-CoV-2 IgM and IgG antibodies. The effect of urea dissociation on the detection sensitivity of early COVID-19 merits further study.

4.
Front Pediatr ; 9: 686600, 2021.
Article in English | MEDLINE | ID: covidwho-1367754

ABSTRACT

Background: Smell and taste dysfunctions are common and have been reported as an early indicator of COVID-19. The prevalence of smell and taste dysfunctions among children with COVID-19 varies greatly across studies, which remains to be summarized quantitatively. This review aimed at examining the pooled prevalence of smell or taste dysfunctions among children with COVID-19, summarizing possible causes of the inconsistencies in the current estimates. Methods: Systematic searches of databases were conducted for literature published until 12 January 2021. Statistical analyses were performed using R software, the pooled prevalence was combined using random effects model. The Loney criteria were used for quality assessment. Results: A total of 18 eligible studies were included. The results showed that the pooled prevalence of smell dysfunction among children with COVID-19 was 15.97% (95% CI: 8.18-23.77%), the pooled prevalence of taste dysfunction among children with COVID-19 was 9.20% (95% CI: 4.25-14.16%), the pooled prevalence of smell or taste dysfunction among children with COVID-19 was 15.50% (95% CI: 10.30-20.70%) and the pooled prevalence of smell and taste dysfunction among children with COVID-19 was 20.21% (95% CI: 14.14-26.28%). Higher smell or taste dysfunction rates were associated with being female, younger age, smaller sample size, patients in Asia, and with comorbidities. Conclusions: Evidence suggests that smell or taste dysfunctions were common among children with COVID-19. Further research is needed to identify effective strategies for preventing and treating smell and taste dysfunctions among children with COVID-19.

5.
Signal Transduct Target Ther ; 5(1): 219, 2020 10 06.
Article in English | MEDLINE | ID: covidwho-834865

ABSTRACT

Convalescent plasma (CP) transfusion has been indicated as a promising therapy in the treatment for other emerging viral infections. However, the quality control of CP and individual variation in patients in different studies make it rather difficult to evaluate the efficacy and risk of CP therapy for coronavirus disease 2019 (COVID-19). We aimed to explore the potential efficacy of CP therapy, and to assess the possible factors associated with its efficacy. We enrolled eight critical or severe COVID-19 patients from four centers. Each patient was transfused with 200-400 mL of CP from seven recovered donors. The primary indicators for clinical efficacy assessment were the changes of clinical symptoms, laboratory parameters, and radiological image after CP transfusion. CP donors had a wide range of antibody levels measured by serology tests which were to some degree correlated with the neutralizing antibody (NAb) level. No adverse events were observed during and after CP transfusion. Following CP transfusion, six out of eight patients showed improved oxygen support status; chest CT indicated varying degrees of absorption of pulmonary lesions in six patients within 8 days; the viral load was decreased to a negative level in five patients who had the previous viremia; other laboratory parameters also tended to improve, including increased lymphocyte counts, decreased C-reactive protein, procalcitonin, and indicators for liver function. The clinical efficacy might be associated with CP transfusion time, transfused dose, and the NAb levels of CP. This study indicated that CP might be a potential therapy for severe patients with COVID-19.


Subject(s)
Antibodies, Neutralizing/administration & dosage , Antibodies, Viral/administration & dosage , Betacoronavirus/pathogenicity , Coronavirus Infections/therapy , Pneumonia, Viral/therapy , Adult , Aged , Antiviral Agents/therapeutic use , Betacoronavirus/immunology , Biomarkers/blood , C-Reactive Protein/metabolism , COVID-19 , COVID-19 Testing , Clinical Laboratory Techniques , Coronavirus Infections/diagnosis , Coronavirus Infections/diagnostic imaging , Coronavirus Infections/immunology , Coronavirus Infections/pathology , Disease Progression , Female , Humans , Immunization, Passive/methods , Liver Function Tests , Male , Middle Aged , Pandemics , Pneumonia, Viral/diagnostic imaging , Pneumonia, Viral/immunology , Pneumonia, Viral/pathology , Procalcitonin/blood , SARS-CoV-2 , Severity of Illness Index , Tomography, X-Ray Computed , Viral Load
6.
J Clin Microbiol ; 58(6)2020 05 26.
Article in English | MEDLINE | ID: covidwho-45977

ABSTRACT

We set out to investigate the interference factors that led to false-positive novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgM detection results using gold immunochromatography assay (GICA) and enzyme-linked immunosorbent assay (ELISA) and the corresponding solutions. GICA and ELISA were used to detect SARS-CoV-2 IgM in 86 serum samples, including 5 influenza A virus (Flu A) IgM-positive sera, 5 influenza B virus (Flu B) IgM-positive sera, 5 Mycoplasma pneumoniae IgM-positive sera, 5 Legionella pneumophila IgM-positive sera, 6 sera of HIV infection patients, 36 rheumatoid factor IgM (RF-IgM)-positive sera, 5 sera from hypertensive patients, 5 sera from diabetes mellitus patients, and 14 sera from novel coronavirus infection disease 19 (COVID-19) patients. The interference factors causing false-positive reactivity with the two methods were analyzed, and the urea dissociation test was employed to dissociate the SARS-CoV-2 IgM-positive serum using the best dissociation concentration. The two methods detected positive SARS-CoV-2 IgM in 22 mid-to-high-level-RF-IgM-positive sera and 14 sera from COVID-19 patients; the other 50 sera were negative. At a urea dissociation concentration of 6 mol/liter, SARS-CoV-2 IgM results were positive in 1 mid-to-high-level-RF-IgM-positive serum and in 14 COVID-19 patient sera detected using GICA. At a urea dissociation concentration of 4 mol/liter and with affinity index (AI) levels lower than 0.371 set to negative, SARS-CoV-2 IgM results were positive in 3 mid-to-high-level-RF-IgM-positive sera and in 14 COVID-19 patient sera detected using ELISA. The presence of RF-IgM at mid-to-high levels could lead to false-positive reactivity of SARS-CoV-2 IgM detected using GICA and ELISA, and urea dissociation tests would be helpful in reducing SARS-CoV-2 IgM false-positive results.


Subject(s)
Betacoronavirus/immunology , Chromatography, Affinity/methods , Clinical Laboratory Techniques/methods , Coronavirus Infections/diagnosis , Enzyme-Linked Immunosorbent Assay/methods , Immunoglobulin M/blood , Pneumonia, Viral/diagnosis , COVID-19 , COVID-19 Testing , False Positive Reactions , Humans , Pandemics , SARS-CoV-2
SELECTION OF CITATIONS
SEARCH DETAIL