scholarly journals Validation of a new automated chemiluminescent anti-SARS-CoV-2 IgM and IgG antibody assay system detecting both N and S proteins in Japan

2020 ◽  
Author(s):  
RIn Yokoyama ◽  
Makoto Kurano ◽  
Yoshifumi Morita ◽  
Takuya Shimura ◽  
Yuki Nakano ◽  
...  
Keyword(s):  
Measurement System ◽  
False Positive ◽  
Laboratory Testing ◽  
Antibody Test ◽  
Measurement Range ◽  
Antibody Assay ◽  
Serum Samples ◽  
Igg Antibody ◽  
Antibody Titers ◽  
Pcr Test

PCR methods are presently the standard for the diagnosis of Coronavirus disease 2019 (COVID-19), but additional methodologies are needed to complement PCR methods, which have some limitations. Here, we validated and investigated the usefulness of measuring serum antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using the iFlash3000 CLIA analyzer. We measured IgM and IgG titers against SARS-CoV-2 in sera collected from 26 PCR-positive COVID-19 patients, 53 COVID-19-suspected but PCR-negative patients, and 20 and 100 randomly selected non-COVID-19 patients who visited our hospital in 2020 and 2017, respectively. The within-day and between-day precisions were regarded as good, since the coefficient variations were below 5%. Linearity was also considered good between 0.6 AU/mL and 112.7 AU/mL for SARS-CoV-2 IgM and between 3.2 AU/mL and 55.3 AU/mL for SARS-CoV-2 IgG, while the linearity curves plateaued above the upper measurement range. We also confirmed that the seroconversion and no-antibody titers were over the cutoff values in all 100 serum samples collected in 2017. These results indicate that this measurement system successfully detects SARS-CoV-2 IgM/IgG. We observed four false-positive cases in the IgM assay and no false-positive cases in the IgG assay when 111 serum samples known to contain autoantibodies were evaluated. The concordance rates of the antibody test with the PCR test were 98.1% for SARS-CoV-2 IgM and 100% for IgG among PCR-negative cases and 30.8% for SARS-CoV-2 IgM and 73.1% for SARS-CoV-2 IgG among PCR-positive cases. In conclusion, the performance of this measurement system is sufficient for use in laboratory testing.

scholarly journals Validation of a new automated chemiluminescent anti-SARS-CoV-2 IgM and IgG antibody assay system detecting both N and S proteins in Japan

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247711
Author(s):  
Rin Yokoyama ◽  
Makoto Kurano ◽  
Yoshifumi Morita ◽  
Takuya Shimura ◽  
Yuki Nakano ◽  
...  
Keyword(s):  
False Positive ◽  
Antibody Test ◽  
Measurement Range ◽  
Antibody Assay ◽  
Serum Samples ◽  
Igg Antibody ◽  
Automated Method ◽  
Antibody Titers ◽  
Pcr Test ◽  
S Proteins

PCR methods are presently the standard for the diagnosis of Coronavirus disease 2019 (COVID-19), but additional methodologies are needed to complement PCR methods, which have some limitations. Here, we validated and investigated the usefulness of measuring serum antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using the iFlash3000 CLIA analyzer. We measured IgM and IgG titers against SARS-CoV-2 in sera collected from 26 PCR-positive COVID-19 patients, 53 COVID-19-suspected but PCR-negative patients, and 20 and 100 randomly selected non-COVID-19 patients who visited our hospital in 2020 and 2017, respectively. The repeatability and within-laboratory precision were obviously good in validations, following to the CLSI document EP15-A3. Linearity was also considered good between 0.6 AU/mL and 112.7 AU/mL for SARS-CoV-2 IgM and between 3.2 AU/mL and 55.3 AU/mL for SARS-CoV-2 IgG, while the linearity curves plateaued above the upper measurement range. We also confirmed that the seroconversion and no-antibody titers were over the cutoff values in all 100 serum samples collected in 2017. These results indicate that this measurement system successfully detects SARS-CoV-2 IgM/IgG. We observed four false-positive cases in the IgM assay and no false-positive cases in the IgG assay when 111 serum samples known to contain autoantibodies were evaluated. The concordance rates of the antibody test with the PCR test were 98.1% for SARS-CoV-2 IgM and 100% for IgG among PCR-negative cases and 30.8% for SARS-CoV-2 IgM and 73.1% for SARS-CoV-2 IgG among PCR-positive cases. In conclusion, the performance of this new automated method for detecting antibody against both N and S proteins of SARS-CoV-2 is sufficient for use in laboratory testing.

scholarly journals Performance verification of anti-SARS-CoV-2-specific antibody detection by using four chemiluminescence immunoassay systems

2020 ◽  
Vol 57 (6) ◽  
pp. 429-434
Author(s):  
Yafang Wan ◽  
Zhijie Li ◽  
Kun Wang ◽  
Tian Li ◽  
Pu Liao
Keyword(s):  
False Positive ◽  
Detection System ◽  
False Positive Rate ◽  
Antibody Test ◽  
The Other ◽  
Antibody Detection ◽  
Igg Antibody ◽  
Chi Square ◽  
Chemiluminescence Immunoassay ◽  
Chi Square Test

Objectives The purpose of the current study was to evaluate the analytical performance of seven kits for detecting IgM/IgG antibodies against coronavirus (SARS-CoV-2) by using four chemiluminescence immunoassay systems. Methods Fifty patients diagnosed with SARS-CoV-2 infection and 130 controls without coronavirus infection from the General Hospital of Chongqing were enrolled in the current retrospective study. Four chemiluminescence immunoassay systems, including seven IgM/IgG antibody detection kits for SARS-CoV-2 (A_IgM, A_IgG, B_IgM, B_IgG, C_IgM, C_IgG and D_Ab), were employed to detect antibody concentrations. The chi-square test, the receiver operating characteristic (ROC) curve and Youden’s index were determined to verify the cut-off value of each detection system. Results The repeatability verification results of the A, B, C and D systems are all qualified. D_Ab performed best (92% sensitivity and 99.23% specificity), and B_IgM performed worse than the other systems. Except for the A_IgM and C_IgG systems, the optimal diagnostic thresholds and cut-off values of the other kits and their recommendations are inconsistent with each other. B_IgM had the worst AUC, and C_IgG had the best diagnostic accuracy. More importantly, the B_IgG system had the highest false-positive rate for testing patients with AIDS, tumours and pregnancies. The A_IgM system test showed the highest false-positive rates among elderly individuals over 90 years old. COVID-2019 IgM/IgG antibody test systems exhibit performance differences. Conclusions The Innodx Biotech Total Antibody serum diagnosis kit is the most reliable detection system for anti-SARS-CoV-2 antibodies, which can be used together with nucleic acid tests as an alternative method for SARS-CoV-2 detecting.

scholarly journals Frequency of antibodies and risk factors associated with Toxoplasma gondii infection in backyard pig production in the city of Mossoró, state of Rio Grande do Norte, Brazil

2019 ◽  
Vol 28 (3) ◽  
pp. 508-513 ◽  
Author(s):  
Isabela Maria Campanelli dos Santos ◽  
Alexandro Iris Leite ◽  
Maria Eduarda Chiaradia Furquim ◽  
Diego Carlos de Souza Zanatto ◽  
Simone de Jesus Fernandes ◽  
...  
Keyword(s):  
Risk Factors ◽  
Rio Grande ◽  
Female Gender ◽  
Immunofluorescence Assay ◽  
P Value ◽  
Serum Samples ◽  
Igg Antibody ◽  
Source Of Infection ◽  
Antibody Titers ◽  
Toxoplasma Gondii Infection

Abstract Toxoplasmosis is an important zoonosis for pregnant women and immunosuppressed people. The pig population also becomes infected by this pathogen, and undercooked or raw meat is an important source of infection for humans. The aims of the present study were to evaluate the rate of exposure of pigs to T. gondii in the municipality of Mossoró, Rio Grande do Norte and seek to identify associations with possible risk factors. Blood samples were collected from 412 pigs and were analyzed using the immunofluorescence assay. Among these 412 serum samples, 40.7% were seropositive for T. gondii. The IgG antibody titers were 64 (56 specimens), 128 (32), 256 (37), 512 (23), 1024 (14), 2048 (5) and 4046 (1). Seropositivity for T. gondii was found to be related (p-value < 0.05) to the following factors: female gender, semi-confined rearing system, use of well water, dewormed animals, presence of cats, goats, sheep, mice and vultures on the farm and carcasses left on the ground. In contrast, seropositivity was not related (p-value < 0.05) to the age of the pigs, type of facility or feeding with human food remains. Preventive measures need to be adopted on the farms studied here, with the aim of decreasing the animals’ intake of sporulated oocysts.

scholarly journals Seroprevalence study of SARS-CoV-2 infection in General Practice in Ireland

BJGP Open ◽  
2021 ◽  
pp. BJGPO.2021.0038
Author(s):  
Michael Edmund O'Callaghan ◽  
Elizabeth Ryan ◽  
Cathal Walsh ◽  
Peter Hayes ◽  
Monica Casey ◽  
...  
Keyword(s):  
General Practice ◽  
Average Length ◽  
Point Of Care ◽  
Antibody Test ◽  
Igg Antibodies ◽  
Antibody Testing ◽  
Igg Antibody ◽  
Seroprevalence Study ◽  
History Of ◽  
Pcr Test

Background: SARS-CoV-2 antibody testing in community settings may help us better understand the immune response to this virus and therefore help guide public health efforts. Aim: Conduct a seroprevalence study of IgG antibodies in Irish GP clinics. Design and Setting: Participants were 172 staff and 799 patients of 15 general practices in the Midwest region of Ireland. Methods: This seroprevalence study utilised 2 manufacturers’ point-of-care (POC) SARS-CoV-2 IgM-IgG combined antibody tests, offered to patients and staff in general practice from mid-June to mid-July 2020. Results: Immunoglobulin G (IgG) seroprevalence was 12.6% in patients attending general practice and 11.1% in staff working in general practice, with administrative staff having the lowest seroprevalence at 2.5% and nursing staff having the highest at 17.6%. Previous symptoms suggestive of SARS-CoV-2 and history of a polymerase chain reaction (PCR) test were associated with higher seroprevalence. IgG antibodies were detected in approximately 80% of participants who had a previous PCR-confirmed infection. Average length of time between participants’ positive PCR test and positive IgG antibody test was 83 days. Conclusion: Patients and healthcare staff in general practice in Ireland had relatively high rates of IgG to SARS-CoV-2 compared to the national average at the time (1.7%). Four-fifths of participants with a history of confirmed COVID-19 disease still had detectable antibodies an average of 12 weeks post-infection. While not proof of immunity, SARS-CoV-2 POC testing can be used to estimate IgG seroprevalence in general practice settings.

scholarly journals Performance Evaluation of the Siemens SARS-CoV-2 Total Antibody and IgG Antibody Test

2021 ◽  
Author(s):  
Lisa Florin ◽  
Karel Maelegheer ◽  
Wouter Vandewal ◽  
Dirk Bernard ◽  
Johan Robbrecht
Keyword(s):  
Antibody Test ◽  
Control Group ◽  
Igg Antibody ◽  
Antibody Assays ◽  
Antibody Titers ◽  
Polymerase Chain ◽  
Kinetics Of ◽  
Antibody Tests ◽  
Positive Controls

Abstract Objective In this study, the performance of 2 commercially available SARS-CoV-2 antibody assays is evaluated. Methods The Siemens SARS-CoV-2 Total (COV2T) and IgG (COV2G) antibody tests were evaluated on a Siemens Atellica IM1300 analyzer. Imprecision was assessed with the CLSI EP15 protocol using positive controls. Ninety control group specimens were analyzed for specificity, and 175 specimens from 58 patients with polymerase chain reaction–confirmed SARS-CoV-2 were measured for the sensitivity and kinetics of the antibody response. Results Within-run and total imprecision were acceptable for both assays. Both tests showed a specificity of 100%. Sensitivity earlier in the disease state was greater for the COV2T assay than for the COV2G assay, but sensitivity &gt;14 days after onset of symptoms approached 100% for both. For all patients, antibody titers remained above the seroconversion cutoff for all follow-up specimens. Conclusion This study shows acceptable performance for both the Siemens COV2T and COV2G test, although seroconversion occurs earlier with the COV2T test.

scholarly journals Inter- and Intralaboratory Comparison ofEhrlichia equi and Human Granulocytic Ehrlichiosis (HGE) Agent Strains for Serodiagnosis of HGE by the Immunofluorescent-Antibody Test

1999 ◽  
Vol 37 (9) ◽  
pp. 2968-2973 ◽  
Author(s):  
Jennifer J. Walls ◽  
Maria Aguero-Rosenfeld ◽  
Johan S. Bakken ◽  
Jesse L. Goodman ◽  
Deloar Hossain ◽  
...  
Keyword(s):  
Serum Sample ◽  
False Positive ◽  
Blood Smear ◽  
Antibody Test ◽  
Serum Samples ◽  
Granulocytic Ehrlichiosis ◽  
Immunofluorescent Antibody ◽  
Human Granulocytic Ehrlichiosis ◽  
Ehrlichia Equi ◽  
Immunofluorescent Antibody Test

Human granulocytic ehrlichiosis (HGE) is usually diagnosed by immunofluorescent antibody (IFA) serology with Ehrlichia equi-infected neutrophils or HGE agent-infected cultured HL60 cells. The HGE agent and E. equi are antigenically diverse, and interpretation of serologic results is also often variable. Thus, we investigated the sensitivity and specificity of various HGE agent and E. equi antigens used for IFA diagnosis by three different laboratories. Serum samples from 28 patients with well-characterized HGE and 9 patients with suspected HGE who were investigated by PCR, blood smear examinations, and serology were used, along with 9 serum samples from patients with other rickettsial and ehrlichial infections. Each serum sample was tested with up to 10 different antigen preparations. Overall, qualitative IFA results agreed in 70% of the samples. Titers among antigens were similar (r = 0.89 to 0.96), but titers of individual samples varied by fourfold or more in 5 of 81 (6%) of the serum samples. Sensitivity ranged from 100% to 82%, and specificity varied from 100% to 67%, but these differences were not significant, even among those tested in the same laboratory or between two different laboratories. Antibodies were detected in 14 to 44% of acute-phase sera from confirmed HGE patients. Most false-positive reactions resulted with Ehrlichia chaffeensis; when these sera were excluded, the specificity of most antigens was 91 to 100%. These data indicate that IFA results often agree and that IFA is useful for diagnosis of HGE in convalescence. However, without further standardization, variability among serologic tests using E. equi and HGE agent isolates for diagnosis of HGE will occasionally provide discrepant results and confound diagnosis.

scholarly journals An age-stratified serosurvey against purified Salmonella enterica serovar Typhi antigens in the Lao People´s Democratic Republic

2021 ◽  
Vol 15 (12) ◽  
pp. e0010017
Author(s):  
Lisa Hefele ◽  
Antony P. Black ◽  
Trinh Van Tan ◽  
Nguyen Tri Minh ◽  
Nguyen Duc Hoang ◽  
...  
Keyword(s):  
Typhoid Fever ◽  
Democratic Republic ◽  
Linear Trend ◽  
Lao Pdr ◽  
Population Based ◽  
Antibody Concentration ◽  
Protein Antigens ◽  
Serum Samples ◽  
Igg Antibody ◽  
Antibody Titers

The epidemiology of typhoid fever in Lao People`s Democratic Republic is poorly defined. Estimating the burden of typhoid fever in endemic countries is complex due to the cost and limitations of population-based surveillance; serological approaches may be a more cost-effective alternative. ELISAs were performed on 937 serum samples (317 children and 620 adults) from across Lao PDR to measure IgG antibody titers against Vi polysaccharide and the experimental protein antigens, CdtB and HlyE. We measured the significance of the differences between antibody titers in adults and children and fitted models to assess the relationship between age and antibody titers. The median IgG titres of both anti-HylE and CdtB were significantly higher in children compared to adults (anti-HylE; 351.7 ELISA Units (EU) vs 198.1 EU, respectively; p<0.0001 and anti-CdtB; 52.6 vs 12.9 EU; p<0.0001). Conversely, the median anti-Vi IgG titer was significantly higher in adults than children (11.3 vs 3.0 U/ml; p<0.0001). A non-linear trend line fitted to the anti-CdtB and anti-HlyE IgG data identified a peak in antibody concentration in children <5 years of age. We identified elevated titers of anti-HlyE and anti-CdtB IgG in the serum of children residing in Lao PDR in comparison to adults. These antigens are associated with seroconversion after typhoid fever and may be a superior measure of disease burden than anti-Vi IgG. This approach is scalable and may be developed to assess the burden of typhoid fever in countries where the disease may be endemic, and evidence is required for the introduction of typhoid vaccines.

scholarly journals Comparative analysis of three point-of-care lateral flow immunoassays for detection of anti-SARS-CoV-2 antibodies in COVID-19 confirmed healthcare workers

2020 ◽  
Author(s):  
Danielle Dias Conte ◽  
Joseane Mayara Almeida Carvalho ◽  
Luciano Kleber de Souza Luna ◽  
Klinger Soares Faíco-Filho ◽  
Ana Helena Perosa ◽  
...  
Keyword(s):  
Healthcare Workers ◽  
Large Scale ◽  
Point Of Care ◽  
Antibody Test ◽  
Cost Effective ◽  
Lateral Flow ◽  
Rt Pcr ◽  
Serum Samples ◽  
Igg Antibody ◽  
Serological Tests

AbstractSince the Coronavirus Disease 2019 (COVID-19) pandemic, Brazil has the third-highest number of confirmed cases and the second-highest number of recovered patients. SARS-CoV-2 detection by real-time RT-PCR is the gold standard in certified infrastructured laboratories. However, for large-scale testing, diagnostics should be fast, cost-effective, widely available, and deployed for the community, such as serological tests based on lateral flow immunoassay (LFIA) for IgM/IgG detection. We evaluated three different commercial point-of-care (POC) LFIAs for anti-SARS-CoV-2 IgM and IgG detection in capillary whole blood of 100 healthcare workers (HCW) previously tested by RT-PCR: 1) COVID-19 IgG/IgM BIO (Bioclin, Brazil), 2) Diagnostic kit for IgM/IgG Antibody to Coronavirus (SARS-CoV-2) (Livzon, China); and 3) SARS-CoV-2 Antibody Test (Wondfo, China). A total of 84 positives and 16 negatives HCW were tested. The data was also analyzed by the number of days post symptoms (DPS) in three groups: <30 (n=26), 30-59 (n=42), and >59 (n=16). Overall detection was 85.71%, 47.62%, and 44.05% for Bioclin, Livzon, and Wondfo, respectively, with a specificity of 100%, and 98.75% for Livzon on storage serum samples. Bioclin was more sensitive (p<0.01), regardless of the DPS. Thus, the Bioclin can be used as a POC test to monitor SARS-CoV-2 seroconversion in HCW.

scholarly journals Seroprevalence of Toxoplasma gondii infection in cats from Curitiba, Paraná, Brazil

2011 ◽  
Vol 20 (3) ◽  
pp. 256-258 ◽  
Author(s):  
Marúcia de Andrade Cruz ◽  
Leila Sabrina Ullmann ◽  
Patrícia Yukiko Montaño ◽  
Juliano Leônidas Hoffmann ◽  
Helio Langoni ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Dietary Habits ◽  
Immunofluorescence Assay ◽  
Serum Samples ◽  
Igg Antibody ◽  
Veterinary Clinic ◽  
Warm Blood ◽  
Potential Risk Factors ◽  
Antibody Titers ◽  
Toxoplasma Gondii Infection

Toxoplasmosis is a worldwide zoonosis caused by the protozoa Toxoplasma gondii which infects all warm-blood vertebrates. This study aimed to assess the seroprevalence of anti-Toxoplasma gondii antibodies in a population of domestic cats seen at a major cat-only veterinary clinic in Curitiba, Paraná State, Southern Brazil. Serum samples were processed by indirect immunofluorescence assay (IIFA) for the detection of IgG. Antibody titers were found in 16.3% (46/282) of sera analyzed, with titers to T. gondii of 16 in eight cats, 64 in 23 cats, 256 in 14 cats and 1024 in one cat. Statistical differences were not found regarding the association with age, gender and different areas of the city (p > 0.05). No significant differences were found in any variable when comparing seropositivity with potential risk factors. The seroprevalence was relatively lower when compared to other Brazilian regions, probably due to the fact that the cats studied were owned, domiciled with restricted dietary habits based on processed foods, restricted access to the street and no prey access. In conclusion, low feline toxoplasmosis seroprevalence may be associated to owned cats due to adequate dietary care and restricted outdoor access, as well as low local environmental exposure.

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