A chemiluminescent immunoassay for human serum Cystatin C (Cys C) was established using a direct-antibody sandwich model. The immunoassay kit uses magnetic separation technology, using magnetic ...particles as the reaction solid phase, alkaline phosphatase as the marker enzyme, and a new chemiluminescent substrate APLS as the substrate. It has the characteristics of high sensitivity and short reaction time. This product uses high-affinity antibodies, resulting in a high specificity. The established method showed good accuracy, uniformity, and stability. The limit of detection was 2.39 ng/mL. The intra-assay coefficient of variation (CV) was 3.36%-6.00%, the interassay CV was 4.12%-5.35%, and the recovery rate was 99.07%. The correlation coefficient (r) of Cys-C kit was 0.999388 greater than or equal to 0.9900. The accuracy of the developed method was tested by automatic chemiluminescence instrument (P > 0.05). The lowest titer was 0.92500, and the highest was 1.10000. The developed method showed a good correlation with the product from Roche by comparing these two kits in 240 clinical samples from China. In total, 1392 clinical patient from China samples were measured using the reagent kit developed in this study.
Developing reliable, rapid, and quantitative point‐of‐care testing (POCT) technology of SARS‐CoV‐2‐specific antibodies and understanding longitudinal vaccination response kinetics are highly required ...to restrain the ongoing coronavirus disease 2019 (COVID‐19) pandemic. We demonstrate a novel portable, sensitive, and rapid chemiluminescent lab‐on‐fiber detection platform for detection of anti‐SARS‐CoV‐2 antibodies: the chemiluminescent lab‐on‐fiber immunosensor (c‐LOFI). Using SARS‐CoV‐2 Spike S1 RBD protein functionalized fiber bio‐probe, the c‐LOFI can detect anti‐SARS‐CoV‐2 immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies with high sensitivity based on their respective horseradish peroxidase‐labeled secondary antibodies. The limits of detection of anti‐SARS‐CoV‐2 IgG and IgM antibodies were 0.6 and 0.3 ng/ml, respectively. The c‐LOFI was successfully applied for direct detection of anti‐SARS‐CoV‐2 antibodies in whole blood samples with simple dilution, which can serve as a finger prick test to rapidly detect antibodies. Furthermore, the longitudinal immune response (>12 months) kinetics following three‐dose inactivated virus vaccines was evaluated based on anti‐SARS‐CoV‐2 IgG detection results, which can provide important significance for understanding the immune mechanism against COVID‐19 and identify individuals who may benefit from the vaccination and booster vaccination. The c‐LOFI has great potential to become a sensitive, low‐cost, rapid, high‐frequency POCT tool for the detection of both SARS‐CoV‐2‐specific antibodies and other biomarkers.
•Enteric Adenovirus are important causes of acute gastroenteritis in children.•Several assays are commercialized for the diagnosis of adenovirus infection.•Performance of bioNexia Rota-Adeno ICT and ...LIAISON® Adenovirus Clinical Laboratory Improvement Amendments was evaluated.•Clinical Laboratory Improvement Amendments showed a higher accuracy (94.4 vs 90.1) and concordance (k: 0.81 vs 0.67) to Real time PCR than ImmunoChromatographic Tests .•Both tests are suitable for the diagnosis of enteric adenovirus infection in symptomatic patients.
The performance of 2 antigenic commercial assays for enteric adenovirus (AdV) infection, bioNexia Rota-Adeno ImmunoChromatographic Tests (ICT) and LIAISON® Adenovirus ChemiLuminescence Immuno Assays (CLIA), was evaluated on 321 stools from children hospitalized for acute gastroenteritis in Palermo, Italy, using a Real time-PCR (Rt-PCR) as reference method. The CLIA showed higher sensitivity (77% vs 60%), accuracy (94.4 vs 90.9) and concordance (k: 0.81 vs 0.67) with respect to ICT, despite equivalent specificity (98.8%). Using the Ct values of the Rt-PCR as a proxy of the fecal viral load, similar Ct values (mean 9.32 vs 9.89) were observed among the true positive samples, whilst a significant difference (P < 0.05) was observed in false negative samples of CLIA (mean Ct 25.68) and ICT (mean Ct 19.87). Cross-reactivity with other enteric viruses was not observed. These results indicate that both the assays tested are suitable for diagnosis of AdV gastroenteritis.
Quantitative SARS-CoV-2 antibody assays against the spike (S) protein are useful for monitoring immune response after infection or vaccination. We compared the results of three chemiluminescent ...immunoassays (CLIAs) (Abbott, Roche, Siemens) and a surrogate virus neutralization test (sVNT, GenScript) using 191 sequential samples from 32 COVID-19 patients. All assays detected >90% of samples collected 14 days after symptom onset (Abbott 97.4%, Roche 96.2%, Siemens 92.3%, and GenScript 96.2%), and overall agreement among the four assays was 91.1% to 96.3%. When we assessed time-course antibody levels, the Abbott and Siemens assays showed higher levels in patients with severe disease (p < 0.05). Antibody levels from the three CLIAs were correlated (r = 0.763–0.885). However, Passing–Bablok regression analysis showed significant proportional differences between assays and converting results to binding antibody units (BAU)/mL still showed substantial bias. CLIAs had good performance in predicting sVNT positivity (Area Under the Curve (AUC), 0.959–0.987), with Abbott having the highest AUC value (p < 0.05). SARS-CoV-2 S protein antibody levels as assessed by the CLIAs were not interchangeable, but showed reliable performance for predicting sVNT results. Further standardization and harmonization of immunoassays might be helpful in monitoring immune status after COVID-19 infection or vaccination.
Vector-borne diseases (VBDs) represent an emerging global threat to public health due to the geographical expansion of arthropod vectors. The study aims to assess the seroprevalence of selected ...vector-borne pathogens (VBPs) in different groups of outdoor workers and the occupational risk factors for exposure to arthropod bites. A cross-sectional study was conducted on 170 workers recruited in two different regions of southern Italy, including farmers, forestry workers, veterinarians, geologists/agronomists and administrative employees, and tested for IgG antibodies against Bartonella henselae, Borrelia spp. Coxiella burnetii and Rickettsia conorii, using a chemiluminescent immunoassay (CLIA). The relationship among job characteristics, tick exposure and the prevalence of seropositive subjects for each pathogen was investigated by applying categorical principal component analysis (CATPCA). A high seroprevalence for C. burnetii (30.0%) and R. conorii (15.3%) was reported, mainly in farmers (67.7% and 54.8%, respectively) and forestry workers (29.0% and 16.1%, respectively), while a low prevalence was observed for B. henselae and Borrelia spp. (8.8% and 4.1%, respectively). The regression equation by CATPCA was significant for C. burnetii and R. conorii (P < 0.001), showing a positive association with job, tick bite exposure, working area and contact with animals. These findings highlight the need of activating an appropriate occupational health response for minimizing the risk of arthropod vector exposure in workplaces, considering specific preventive measures in particular in high-risk job categories.
Serological tests for COVID-19 are important in providing results for surveillance and supporting diagnosis. Investigating the serological response in COVID-19 patients with different disease ...severity is important for assessing the clinical utility of serological assays.
However, few studies have investigated the clinical utility of antibody assays for COVID-19 or differences in antibody response in association with disease severity.
The study aimed to evaluate the clinical characteristics and clinical utility of VITROS SARS-CoV-2 antibody tests according to COVID-19 severity in patients in Japan.
We analysed 255 serum specimens from 130 COVID-19 patients and examined clinical records and laboratory data. Presence of total (IgA, IgM, and IgG) and specific IgG antibody for the spike 1 antigen of SARS-CoV-2 was determined using VITROS Anti-SARS-CoV-2 antibody tests.
Overall, 98 (75.4 %) and 32 (24.6 %) patients had mild and severe COVID-19, respectively. On admission, 76 (58.5 %) and 45 (34.6 %) patients were positive for total and IgG antibody assays. Among 91 patients at discharge, 90 (98.9 %) and 81 (89.0 %) were positive for total and IgG antibody, respectively. Clinical background and laboratory findings on admission, but not the prevalence or concentration of total or IgG antibody, were associated with disease prognosis. Total and IgG antibody intensities were significantly higher in severe cases than in mild cases in serum collected >11 days after onset, but not within 10 days.
VITROS Anti-SARS-CoV-2 total and IgG assays will be useful as supporting diagnostic and surveillance tools and for evaluation of humoral immune response to COVID-19. Optimal prediction of disease prognosis is made from considering both clinical history and laboratory findings.
In the context of measles elimination, the identification of recent infections is important for clinical laboratories. Serological diagnosis is achieved by detecting specific IgG and IgM. Recently an ...automated chemiluminescent immunoassay (CLIA) (Liaison, DiaSorin, Italy) has been used to quantify the measles antibody. The aim of this study was to compare this assay with Enzygnost ELISA (Siemens, Germany), with final classification of discrepancies by indirect immunofluorescence (Euroimmun, Germany). For measles IgM, 204 sera were analyzed: 50 IgM‐positive, 104 IgM‐negative/IgG‐positive, and 50 from other viral infections (B19V, rubella, mumps, CMV, and EBV). For the measles IgG assay, 162 samples were tested: 106 were positive and 56 were negative. For measles IgM, the sensitivity and specificity of CLIA against ELISA were 94% (95% CI: 83.2–98.6) and 100% (95% CI: 97.1–100), respectively; the corrected figures after the final classification of discrepancies were 100% (95% CI: 91.0–100) and 99.4% (95% CI: 96.1–100), respectively. In relation to IgG, the sensitivity and specificity of CLIA against ELISA were, respectively, 97.2% (95% CI: 91.7–99.4) and 92.9% (95% CI: 82.5–97.7), and 95.5% (95% CI: 89.5–98.3) and 100% (95% CI: 91.8–100) after the final classification. CLIA showed excellent sensitivity and specificity in detecting measles IgG and IgM antibodies, eliminating the need to aliquot specimens before carrying out the assay.
The addition of ethylenediamine tetra-acetic acid (EDTA) to serum can affect the measurement of cortisol by chemiluminescent enzyme immunoassay (CEIA); addition of magnesium chloride (MgCl2) may ...reverse the effects. However, similar characteristics for thyroxine (T4) measurement are unknown. We measured cortisol and T4 in paired EDTA-anticoagulated plasma and serum samples from 50 dogs. Additionally, both hormones were measured in 15 samples of each type after the addition of MgCl2. Samples were collected under routine clinical conditions; therefore, specific EDTA concentrations in plasma samples were unknown. Cortisol and T4 values were significantly different comparing plasma and serum samples in the absence of MgCl2. For cortisol and T4, EDTA-plasma concentrations were 51.2% and 43.7% higher than serum, respectively (p < 0.001 for both). The addition of MgCl2 to plasma significantly decreased the measured cortisol concentrations (p < 0.001) but not T4 (p = 0.44). After addition of MgCl2, cortisol concentrations in EDTA-plasma were no longer significantly different from serum, whereas T4 concentrations in EDTA-plasma remained significantly different from serum. In the clinical setting in which tubes may be underfilled, use of EDTA-plasma significantly increases the measured concentration of cortisol and T4 obtained by CEIA. Addition of MgCl2 to EDTA-plasma can overcome the effects of EDTA when measuring cortisol, but not T4. Thus, T4 should not be measured in EDTA-plasma.
An assay of circulating progesterone (P4) is commonly used to estimate progress through late gestation in the bitch. Point-of-care assays provide rapid results, a major advantage over ...laboratory-based assays. This study aims to compare P4 levels determined by the Catalyst® Progesterone point-of-care assay with those determined by chemiluminescent immunoassay (CLIA) and to identify the expected distribution of Catalyst P4 levels at time intervals 3 days prior to the onset of parturition in pregnant bitches. Twenty-eight pregnant bitches carrying two or more fetuses were admitted to a specialist veterinary reproduction hospital 53 days after the onset of cytological diestrus or, when that date was not known, 57 days after the last mating. Vaginal speculum examinations were performed every 6 h until the onset of cervical dilatation (TCD). Serum samples were collected twice daily (08h00 and 18h00) until TCD. For most samples, fresh serum was assayed for P4 immediately using the Catalyst assay (CatP4), then frozen until assayed by CLIA (IMMULITE 2000; ImmP4). However, for some samples, CatP4 was not analyzed prior to freezing. For these data points (
n
= 33), CatP4 for fresh serum was estimated from CatP4 assayed on frozen-thawed serum, based on a comparison between CatP4 on fresh vs. frozen-thawed sera. In comparison to ImmP4, CatP4 levels up to and including 7 nmol/L appear to have a constant bias of −1.69 nmol/L (limits of agreement −4.91 to 1.52), while levels >7 nmol/L appear to have a proportional bias of −17.9% (limits of agreement −68.6% to 32.7%). Bootstrapped percentiles of CatP4 results spanned 0.4–9 nmol/L within 12 h of TCD, 0.9–11 nmol/L 12–24 h from TCD, and 2.2–13.5 nmol/L 24–36 h from TCD. A CatP4 >9 nmol/L indicates a bitch that is unlikely to reach TCD within 12 h. Bitches with CatP4s below 3.5 nmol/L are likely to reach TCD within 36 h and bitches with a CatP4 below 2.2 nmol/L are likely to reach TCD within 24 h. In conclusion, the Catalyst Progesterone assay provides rapid assessment of circulating P4 in the bitch, with clinical application in the monitoring of late term pregnant bitches.
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