A Low-Cost SARS-CoV-2 rRBD ELISA to Detect Serostatus in Ecuadorian Population with COVID-19

ABSTRACTLaboratory diagnosis of the COVID-19 relies on RT-PCR to amplify specific fragments of SARS-CoV-2 genome. However, serological tests are required to determine the immune response elicited after infection. Here, we analyzed convalescent sera collected from positive individuals by RT-PCR to SARS-CoV-2 (n = 78), Zika (n = 20), dengue (n = 20), chikungunya (n = 54), intestinal parasites (n = 11), and HIV (n = 1), from different areas of Ecuador, with an in-house ELISA using a SARS-CoV-2 receptor binding domain recombinant (rRBD) antigen to detect IgG antibodies elicited by SARS-CoV-2 infection. Of the 78 samples positive for SARS-CoV-2 by RT-PCR, 73 showed high absorbance value compared with the cutoff and five were negative. All tested sera from other infections showed no reactivity. Sensitivity, specificity, positive predictive value, and negative predictive value were 93.6%, 100%, 100%, and 95.4%, respectively. This in-house anti-IgG rRBD ELISA offers an economic and simple alternative to determine IgG immune responses after SARS-CoV-2 infection.

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Methods for Molecular Surveillance of Influenza Used in Macedonia

PRILOZI ◽

10.2478/prilozi-2014-0003 ◽

2014 ◽

Vol 35 (2) ◽

pp. 25-30

Author(s):

Golubinka Bosevska ◽

Elizabeta Janceska ◽

Gordana Kuzmanovska ◽

Vladimir Mikik ◽

Nikola Panovski

Keyword(s):

Influenza Virus ◽

Predictive Value ◽

Influenza A ◽

Rna Extraction ◽

Influenza Virus Infection ◽

Laboratory Diagnosis ◽

Influenza Viruses ◽

Rt Pcr ◽

Two Samples ◽

Nose And Throat

AbstractThe aim: To present and compare different Nucleic Acid Testing assays used for laboratory diagnosis of influenza virus infection in our country.Materials and methods: Respiratory samples used were nose and throat swabs. The RNA extraction was performed with a QIAamp viral RNA kit. During the season 2009–2010 the first 25 samples were tested with: conventional gel-based RT-PCR and CDC rtRT-PCR using published specific matrix and HA gene primers and probes for influenza virus typing and subtyping.Results: Of 25 samples tested with conventional RT-PCR7(28%) were positive for influenza A, but negative for A/H1seasonal and A/H3. Retested with rtRT-PCR 9(36%) were positive for influenza A, 8(32%) were positive for A/H1pdm and 1(4%) was A/H3. Two samples positive with rtRT-PCR for influenza A were negative with RT-PCR. The sensitivity of the RT-PCR in comparison with rtRT-PCR is 100% and the specificity is 88.89%. Positive predictive value for RT-PCR is 77.78%, and negative predictive value is 100%. RT-PCR is a four-step and rtRT-PCR a one-step procedure. The turn-around time of RT-PCR is 6 hours and for rtRT-PCR it is 2 hours.Discussion and conclusion: For surveillance purposes nose and throat swabs are the more easy and practical to collect. It was proved that RT-PCR is too laborious, multi-step and time-consuming. The sensitivity of both assays is equal. The specificity of rtRT-PCR is higher. NAT assays for detection of influenza viruses have become an integral component of the surveillance programme in our country. They provide a fast, accurate and sensitive detection of influenza.

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Differences in clinical predictors of influenza in adults and children with influenza-like illness

Open Medicine ◽

10.2478/s11536-009-0089-3 ◽

2010 ◽

Vol 5 (1) ◽

pp. 41-48 ◽

Cited By ~ 3

Author(s):

Maja Sočan ◽

Katarina Prosenc ◽

Mateja Nagode

Keyword(s):

Clinical Data ◽

Predictive Value ◽

Influenza A ◽

Influenza Infection ◽

Care Hospital ◽

Rt Pcr ◽

Clinical Predictors ◽

Influenza Like Illness ◽

Breath Sounds ◽

Sensitivity Specificity

AbstractInfluenza contributes significantly to morbidity and mortality in the winter season. The aim of the study was to identify clinical signs and symptoms most predictive of influenza infection in children and adults with influenza-like illness. A prospective systematic sampling analysis of clinical data collected through sentinel surveillance system for influenza in 32 primary care centers and one tertiary care hospital in Slovenia during two consecutive influenza seasons (2004/2005 and 2005/2006) was carried out. Children and adults who had influenza-like illness, defined as febrille illness with sudden onset, prostration and weakness, muscle and joint pain and at least (cough, sore throat, coryza) were included and tested for influenza A and B virus, adenovirus, respiratory syncytial virus and enterovirus by RT-PCR. Clinical data were evaluated in statistical models to identify the best predictors for the confirmation of influenza for children (under age of 15) and adults. Of 1,286 patients with influenza-like symptoms in both seasons 211 were confirmed to have influenza A or B alone and compared to 780 influenza-negative patients. A fever over 38°C, chills, headache, malaise and sore eyes revealed a significant association with positive RT-PCR test for influenza virus in children. In adults, only three symptoms were significantly related to PCR-confirmed influenza infection: fever, cough and abnormal breath sounds. The stepwise logistic regression analysis showed that four symptoms predicted influenza in children: fever (38°C or more) (p=0.010), headache (p=0.030), cough (p=0.044) and absence of abnormal breathing sounds (p=0.015) with sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 5.1%, 98.1%, 57.1% and 80.1%, respectively. For adults, the strongest impact on influenza positivity was found for fever (p=0.008) and cough (p=0.085). The model for adults had less favorable characteristics, with sensitivity, specificity, PPV and NPV of 0%, 100%, 0% and 76.4%, respectively. Differences in clinical predictors of influenza in children compared to adults were found. The model for adults was acceptable but not a good one. The model for children was found to be more reliable than the prediction model for adults.

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Quantification of IgG specific antibodies in recovered COVID -19 patients and its association with disease severity

RAS Microbiology and Infectious Diseases ◽

10.51520/2766-838x-14 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Saurabh Srivastava ◽

Shalini Bahadur ◽

Shalini Shukla ◽

Rashmi Upadhyay ◽

Jaganathan Sickan ◽

...

Keyword(s):

Vaccination Strategy ◽

Public Health Research ◽

Quantitative Assay ◽

Serological Response ◽

Igg Antibodies ◽

Rt Pcr ◽

Serological Tests ◽

Entire Cohort ◽

Mild Disease ◽

The Mean

Background: Serological tests for anti-SARS-CoV-2 antibodies can provide valuable information in epidemiologic and public health research. However, the data is limited on serological response post COVID-19 infection. Objective: To investigate the use of ARCHITECT SARS CoV-2 IgG II Quantitative assay to quantify the IgG antibodies in recovered COVID-19 infections. Methods: Abbott SARS-CoV-2 IgG assays were performed using the ARCHITECT Quantitative chemiluminescent microparticle immunoassay to detect IgG against SARS-CoV-2 S1 receptor binding domain (RBD) in serum and plasma. Patients having IgG concentrations above ≥50 AU/mL were defined as positive. We analyzed 333 COVID-19 patients who were tested negative by RT-PCR not more than three months after testing positive. Results: The mean age of the population was 34.3 years and 95% were male. About 93% of the patients had mild disease and rest had moderate disease. The mean IgG levels in the entire cohort was 1860.27 AU/mL, the lowest and highest value detected by ARCHITECT SARS CoV-2 IgG II Quantitative Assay (Abbott Laboratories, USA) were 39.8 AU/mL and 43657.4 AU/mL, respectively. While patients with moderate COVID-19 disease had numerically higher IgG levels than patients with mild disease, the difference was not statistically significant (1787.7 AU/mL vs. 2865.39 AU/mL, p=0.21). In 97% of the patients, IgG antibodies could be detected up to 95 days after testing negative on RT-PCR. Conclusion: Patients with moderate COVID-19 disease may develop higher IgG antibodies than in patients with mild disease. Antibodies can be detected in majority of recovered individuals for more than 90 days which may be valuable in developing future vaccination strategy.

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COVID-19 clinical and laboratory diagnosis overview

Journal of Egyptian Public Health Association ◽

10.1186/s42506-021-00087-w ◽

2021 ◽

Vol 96 (1) ◽

Author(s):

Rania A. Zayed ◽

Dalia Omran ◽

Abeer A. Zayed

Keyword(s):

False Negative ◽

Clinical Decision ◽

Laboratory Diagnosis ◽

Clinical Suspicion ◽

Laboratory Diagnostics ◽

Main Body ◽

Rt Pcr ◽

Serological Tests ◽

Negative Results ◽

Important Approach

Abstract Background COVID-19 was identified in Wuhan, China, in December 2019, and rapidly spread worldwide, being declared global pandemic on the 11th of March 2020. Since its emergence, COVID-19 has raised global concerns associated with drastic measures that were never adopted in any previous outbreak, to contain the situation as early as possible. Main body The 2019 novel corona virus (2019-nCoV) or SARS-CoV-2 is the causative agent of COVID-19. 2019-nCoV genetic sequence was rapidly identified within few days since the first reported cases and RT-PCR kits became available for COVID-19 diagnosis. However, RT-PCR diagnosis carries a risk of false-negative results; therefore, additional serologic tests are needed. In this review, we summarize the clinical scenario that raises suspicion of COVID-19 and available laboratory diagnostics. Conclusion The most important approach in the battle against COVID-19 is rapid diagnosis of suspicious cases, timely therapeutic intervention and isolation to avoid community spread. Diagnosis depends mainly on PCR testing and serological tests. However, even in the context of negative lab test results and clinical suspicion of COVID-19 infection, clinical decision should be based on clinical suspicion.

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Validation of rapid antibody (IgG-IgM) test kit for SARS COV-2 infection in Qatar

Journal of Public Health Research ◽

10.4081/jphr.2021.2421 ◽

2021 ◽

Author(s):

Jesha Mundodan ◽

Samina Hasnain ◽

Hayat Khogali ◽

Soha Shawqi Al Bayat ◽

Dina Ali ◽

...

Keyword(s):

Predictive Value ◽

Local Population ◽

Rapid Test ◽

Antibody Test ◽

Molecular Testing ◽

Rt Pcr ◽

Test Kit ◽

Asymptomatic Individuals ◽

Sensitivity Specificity ◽

Rapid Antibody

Background: In response to the growing coronavirus disease 2019 (COVID-19) pandemic and the shortage of laboratory based molecular testing capacity and reagents, multiple diagnostic test manufacturers have developed rapid and easy to use devices to facilitate testing outside laboratory settings. These kits are either based on detection of proteins from SARS-CoV-2 virus or detection of antigen or human antibodies generated in response to the infection. However, it is important to understand their performance characteristics and they must be validated in the local population setting.Design and Methods: The objective is to assess the validity of the rapid test for IgG and IgM immunoglobulins compared to the current gold standard reverse transcription polymerase chain reaction (RT-PCR) test. A total of 16951 asymptomatic individuals were tested by the Ministry of Public Health track-and-trace team using both rapid immunodiagnostic test and RT-PCR as part of screening across various random settings with potential risk of community interaction prior to gradual lifting of restrictions in Qatar. Rapid test was considered to be posiive if both IgG and IgM are positive, while only IgG/IgM positive was considered as rapid test negative. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated.Results: The sensitivity of rapid test kit was found to be 0.9%, whereas the specificity was found to be 97.8%. the PPV was found to be 0.3% whereas the NPV was found to be 99.4%.Conclusion: Based on the outcome and results of the study, it appears that the sensitivity and PPV of the rapid antibody test are low. As such, this test is not recommended for use to assist in taking clinic-based decisions or decisions related to quarantine/isolation.

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Evaluation of nine serological rapid tests for the detection of SARS-CoV-2

Revista Panamericana de Salud Pública ◽

10.26633/rpsp.2020.149 ◽

2020 ◽

Vol 44 ◽

pp. 1

Author(s):

Marcela Mercado ◽

Jeadran Malagón-Rojas ◽

Gabriela Delgado ◽

Vivian Vanesa Rubio ◽

Lida Muñoz Galindo ◽

...

Keyword(s):

Study Groups ◽

Cross Sectional Study ◽

Igg Antibodies ◽

Sectional Study ◽

Rt Pcr ◽

Serum Samples ◽

Serological Tests ◽

Cross Sectional ◽

Diagnostic Aid ◽

Rapid Tests

Objective. To evaluate the operative capacity of nine serological rapid tests to detect the IgM/IgG antibodies response in serum from patients with SARS-CoV-2 in different clinical stages. Methods. A cross-sectional study of serological rapid tests was designed to compare the performance of the evaluated immunochromatographic tests for the diagnosis of SARS-CoV-2. A total of 293 samples was used, including negatives, asymptomatic, and symptomatic serum samples. Results. The sensitivity of the evaluated tests was low and moderate in the groups of asymptomatic serum samples and the group of serums coming from patients with less than 11 days since the onset of the symptoms. The specificity for the anti-SARS-CoV-2 antibodies tests ranged between 86.5%-99% for IgM and 86.5%-99.5% for IgG. The sensitivity and the likelihood ratio were different according to the study groups. The usefulness of these tests is restricted to symptomatic patients and their sensitivity is greater than 85% after 11 days from the appearance of symptoms. Conclusions. Serological tests are not an adequate strategy for the identification of asymptomatic and pre-symptomatic patients. Serological rapid tests for the detection of specific anti-SARS-CoV-2 antibodies can be used as a diagnostic aid, but diagnosis must be confirmed by RT-PCR. Rapid tests should be reserved for patients with symptoms lasting more than 11 days.

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Seroprevalence and epidemiological characteristics of immunoglobulin M and G antibodies against SARS-CoV-2 in asymptomatic people in Wuhan, China

10.1101/2020.06.16.20132423 ◽

2020 ◽

Cited By ~ 2

Author(s):

Ruijie Ling ◽

Yihan Yu ◽

Jiayu He ◽

Jixian Zhang ◽

Sha Xu ◽

...

Keyword(s):

General Hospital ◽

Rural Areas ◽

Immunoglobulin M ◽

Igg Antibodies ◽

Rt Pcr ◽

Serological Tests ◽

Infected Population ◽

Significant Difference ◽

Epidemiological Characteristics ◽

Back To Work

SummaryBackgroundThe seroprevalence of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may be a more reliable approach to detect true infected population, particularly in asymptomatic persons. Few studies focus on the diagnosis of COVID-19 patients using serological tests. To detect and assess asymptomatic infections of COVID-19 among people in Wuhan, the epicenter of the COVID-19 pandemic in China, and provide evidence for planning adequate public health measures, we collected and analyzed the clinical data in the Wuhan General Hospital mandatory for 16- to 64-year-old asymptomatic people. This retrospective study estimated the seroprevalence of IgM and IgG and compared the epidemiological characteristics of asymptomatic SARS-CoV-2-infected population.MethodsDemographical and radiological data were collected from the Wuhan General Hospital between March 26 and April 28, 2020. Serological tests for IgM and IgG antibodies against SARS-CoV-2 were conducted with a colloidal gold method. Nucleic acid sequences of viruses were detected with RT-PCR. Statistical analyses were carried out using SPSS 20.0 software.FindingsBetween March 26 and April 28, 2020, 18,391 asymptomatic back-to-work participants were enrolled. Among them, 89 had positivity for IgM (0·48%, 95% confidence interval (CI): 0·38–0·58%); 620 cases had IgG positivity (3·37%, 95% CI: 3·11–3·64%), and 650 cases had either IgG positivity or IgM positivity (3·53%, 95% CI: 3·26–3·80%). After standardizing for the genders and ages in the population of Wuhan, the overall standardized seroprevalence of IgG was 3·33% (95% CI: 3·07–3·59%) and the standardized seroprevalence of IgG was 3·01% (95% CI: 2·69–3·33%) among males and 3·66% (95 % CI: 3·23–4·09%) among females. The standardized seroprevalence of IgG was higher in women than in men with a significant difference (χ2 = 2,060·3, p < 0·01). By a detection method adjustment, the seroprevalence of IgG was 1·57% (95% CI: 1·39–1·75%) in all medical records, of which males were 1·96% (95% CI: 1·64–2·28%), and females were 1·19% (95% CI: 0·99–1·39%). The assay-adjusted seroprevalence of IgG was higher in women than in men, and the difference was significant (χ2 = 5,871·0, p < 0·01). The differences were significant for the seroprevalence of IgG among people who went back to work in different categories of workplace (χ2 = 198·44, p < 0·01). The differences in seroprevalence for IgG positivity or IgM positivity among people who went back to work in different urban and rural areas was also significant (χ2 = 45·110, p < 0·01). Calculated as IgG and/or IgM antibody positivity, the number of new infections was reduced by 64·8% from March 26 to April 28, 2020. Based on the census population aged 16–64 years in Wuhan in 2017, we estimated that 172,340 (95% CI: 157,568–187,112) asymptomatic people aged 16–64 years were infected with SARS-CoV-2 in Wuhan between March 25 and April 28, 2020. This estimate was 3·4-times higher than the officially reported 50,333 infections on April 28.InterpretationThe seropositivity rate in Wuhan indicated that RT-PCR-confirmed patients only represented a small part of the total number of cases. Seropositivity progressively decreased in the Wuhan population from March 26 to April 28, 2020, comparable to Japan and Denmark, but well below the level reported in New York, Iran, Italy, and Germany. The prevalence of asymptomatic infection was higher in women than in men among people who went back to work in Wuhan. The low seroprevalence suggests that most of the population remains susceptible to COVID-19.FundingThe Emergency Management Project of the National Natural Science Foundation of China (81842035) and Advisory Research Project of the Chinese Academy of Engineering in 2019 (2019-XZ-70).

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Assessment of the Rapid Immunochromatographic Test as a Diagnostic Tool for Norovirus Related Diarrhea in Children

Folia Medica Indonesiana ◽

10.20473/fmi.v55i1.12557 ◽

2019 ◽

Vol 55 (1) ◽

pp. 48

Author(s):

Reza Gunadi Ranuh ◽

Alpha Fardah Athiyyah ◽

Deanty Ayu PA ◽

Andy Darma ◽

Dadik Rahardjo ◽

...

Keyword(s):

Developing Countries ◽

Diagnostic Tool ◽

Predictive Value ◽

Gold Standard ◽

Pediatric Patients ◽

Immunochromatographic Test ◽

Rt Pcr ◽

Gold Standard Method ◽

Stool Samples ◽

Sensitivity Specificity

In developing countries, Norovirus is the second-leading cause of acute diarrhea, after rotavirus. The approved gold standard method for diagnosis of norovirus infection is RT-PCR. The rapid immunochromatographic test is a novel and expedient method for diagnosing norovirus that is relatively affordable. However, the use of the rapid immunochromatographic test remains controversial because of its accuracy. This study aimed to explore whether the rapid immunochromatographic test could be used for diagnosing norovirus-related diarrhea in children. Rapid immunochromatographic test (QuickNaviTM-Norovirus2) and RT-PCR on stool samples was used to diagnose norovirus. Stool samples were obtained from pediatric patients aged between 1 and 60 months who had diarrhea and were admitted to the pediatric ward at Dr. Soetomo General Hospital Surabaya, between April 2013 and March 2014. Ninety-four subjects provided stool samples that were tested using QuickNaviTM-Noro2 and RT-PCR. Using the test, 64 samples tested positive for norovirus and 30 tested negatives. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the rapid immunochromatographic test were consecutively 90.3%, 42.9%, 43.8%, 90%, and 58.5%. RT-PCR was used to test all samples to assess the accuracy, which showed that one from 31 samples contained the GI strain (1.1%), while 30 samples (32%) contained the GII strain. This study definitively establishes that the rapid immunochromatography test is not sufficiently accurate for use as a screening or diagnostic tool in norovirus-related diarrhea cases in children.

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Coronavirus Disease 2019 (COVID-19) in Italy: Double reading of chest CT examination

10.21203/rs.3.rs-36750/v1 ◽

2020 ◽

Author(s):

Reginelli Alfonso ◽

Grassi Roberto ◽

Feragalli Beatrice ◽

Belfiore Maria Paola ◽

Montanelli Alessandro ◽

...

Keyword(s):

Predictive Value ◽

False Negative ◽

Viral Pneumonia ◽

Ct Diagnosis ◽

Rt Pcr ◽

Ct Examination ◽

Polymerase Chain ◽

Sensitivity Specificity ◽

Age Range ◽

Pcr Test

Abstract OBJECTIVETo assess the performance of the second reading of chest Compute Tomography (CT) examinations by expert radiologists in patients with discordance between the reverse transcription real-time fluorescence polymerase chain reaction (RT-PCR) test for COVID-19 viral pneumonia and the first CT report.MATERIALS AND METHODS.Three hundred seventy-heigth patients were included in this retrospective study (121 women and 257 men; 71 years of median age - range, 29–93 years) subjected to RT-PCR test for suspicious COVID-19 infection. All patients were subjected to CT examination in order to evaluate the pulmonary disease involvement by COVID-19. CT images were reviewed first by two radiologists who identified COVID-19 typical CT patterns and then reanalyzed by anoter two radiologists using a CT structured report for COVID-19 diagnosis.RESULTS.The median temporal window between RT-PCRs execution and CT scan was 0 days with a range of [-9, 11] days. RT-PCR test was resulted positive in 328/378 (86.8%). Discordance between RT-PCR and CT findings for viral pneumonia was revealed in 60 cases. The second reading changed the CT diagnosis in 16/60 (26.7%) cases contributing to increase the concordance with the RT-PCR. Among these 60 cases, 8 were false negative with positive RT-PCR, and 36 were false positive with negative RT-PCR. Sensitivity, specificity, positive predictive value and negative predictive value of CT were respectively of 97.3%, 53.8%, 89.0%, and 88.4%.CONCLUSION.Double reading of CT could increase the diagnostic confidence of radiological interpretation in COVID-19 patients. Using expert second readers could reduce the rate of discrepant cases between RT-PCR results and CT diagnosis for COVID-19 viral pneumonia.

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Analysis of the accuracy of different laboratory methods for the diagnosis of intestinal parasites from stray and domiciled cats (Felis catus domesticus) in Goiânia, Goiás, Brazil

Revista Brasileira de Parasitologia Veterinária ◽

10.1590/s1984-29612018004 ◽

2018 ◽

Vol 27 (1) ◽

pp. 94-97

Author(s):

Jaqueline Ataíde Silva Lima ◽

Hanstter Hallison Alves Rezende ◽

Tamires Mariana Dias Damas Rocha ◽

Ana Maria de Castro

Keyword(s):

Toxoplasma Gondii ◽

Negative Predictive Value ◽

Predictive Value ◽

Intestinal Parasites ◽

Felis Catus ◽

Accuracy Analysis ◽

Laboratory Methods ◽

Fecal Samples ◽

Stray Cats ◽

Sensitivity Specificity

Abstract Cats are carriers of zoonotic agents to humans, including intestinal parasites. The purpose of this study was to analyze the accuracy of different laboratory methods for the diagnosis of intestinal parasites. Fecal samples were processed by the Willis, Sheather, Faust and Hoffman-Janer-Pons-Lutz (HJPL) methods. Accuracy analysis was performed determining the sensitivity, specificity, positive and negative predictive value and Kappa. A total of 149 fecal samples were collected, 65 from stray cats and 84 from domiciled cats. The prevalence of intestinal parasites in stray cats was 60% while in domiciled cats it was 17%. In the analysis of accuracy, the techniques that showed the greatest accuracy for Ancylostomids were Willis and Faust, for Cystoisospora spp. Sheather with Faust or HPJL, and Toxoplasma gondii/Hammondia hammondi the association between Willis and Faust. Therefore, for a reliable evaluation of the prevalence of intestinal parasites, at least two different techniques should be used in parasitological exams of feces.

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