Canine enteric coronavirus (CCV) and canine parvovirus type 2 (CPV-2) are the main pathogens responsible for acute gastroenteritis in dogs, and both single and mixed infections are common. This study aimed to establish a double-labeling time-resolved fluorescence immunoassay (TRFIA) to test and distinguish CCV and CPV-2 diseases.
A sandwich double-labeling TRFIA method was established and optimized using europium(III) (Eu3+)/samarium(III) (Sm3+) chelates. CCV/CPV-2 antigens were first captured by the immobilized antibodies. Then, combined with Eu3+/Sm3+-labeled paired antibodies, the Eu3+/Sm3+ fluorescence values were detected after dissociation to calculate the CCV/CPV-2 ratios. The performance, clinical performance and methodology used for laboratory (sensitivity, specificity, accuracy and stability) testing were evaluated.
A double-label TRFIA for CCV and CPV-2 detection was optimized and established. The sensitivity of this TRFIA kit was 0.51 ng/mL for CCV and 0.80 ng/mL for CPV-2, with high specificity for CCV and CPV-2. All the accuracy data were less than 10%, and the recovery ranged from 101.21 to 110.28%. The kits can be temporarily stored for 20 days at 4 °C and can be stored for 12 months at temperatures less than - 20 °C. Based on a methodology comparison of 137 clinically suspected patients, there was no statistically significant difference between the TRFIA kit and the PCR method. Additionally, for CCV detection, the clinical sensitivity was 95.74%, and the clinical specificity was 93.33%. For CPV-2 detection, the clinical sensitivity was 92.86%, and the clinical specificity was 96.97%.
In this study, a double-label TRFIA kit was prepared for CCV and CPV-2 detection with high laboratory sensitivity, specificity, accuracy, stability, clinical sensitivity and specificity. This kit provides a new option for screening/distinguishing between CCV and CPV-2 and may help improve strategies to prevent and control animal infectious diseases in the future.

UNASSIGNED: The present study aimed to evaluate the clinical value of Combined Detection of serum soluble T-cell immunoglobulin 3 (sTim-3) with carcinoembryonic antigen (CEA) or glycotype antigen 19-9 (CA19-9) for Postoperative Recurrence of Colorectal Cancer (CRC) Diagnosis.
UNASSIGNED: The serum sTim-3 was measured by highly sensitivity TRFIA, and serum CEA and CA19-9 were obtained through the collection of clinical data. Quantitative detection of serum sTim-3, CEA, CA19-9 in 90 patients after the CRC surgery (52 postoperative recurrence and 38 no-postoperative recurrence), 21 patients with colorectal benign tumors, and 67 healthy controls. To analyze the clinical diagnostic value of combined detection of sTim-3 with CEA or CA19-9 to test whether patients have recurrence after CRC surgery.
UNASSIGNED: The sTim-3 (15.94±11.24ng/mL) in patients after CRC surgery was significantly higher than in healthy controls (8.95±3.34ng/mL) and colorectal benign tumors (8.39±2.28ng/mL) (P < 0.05), and sTim-3 (20.33±13.04ng/mL) in CRC postoperative recurrent group was significantly higher than in the group without recurrence after CRC surgery (9.94±2.36ng/mL) (P < 0.05). In terms of detecting postoperative recurrence after CRC surgery, combined detection of sTim-3 and CEA (AUC: 0.819, sensitivity: 80.77%, specificity: 65.79%), sTim-3 and CA19-9 test (AUC: 0.813, sensitivity: 69.23%, specificity: 97.30%) was significantly better than the CEA single test (AUC: 0.547, sensitivity: 63.16%, specificity: 48.08%) and CA19-9 single test (AUC: 0.675 sensitivity: 65.38%, specificity: 67.57%), Delong test P < 0.05.
UNASSIGNED: The efficacy of CEA and CA19-9 single test was not optimal, and the combination of sTim-3 in serum could significantly improve the sensitivity and specificity of detecting patient recurrence after CRC surgery.

Deoxynivalenol (DON) contamination of food crops and feeds is almost impossible to avoid completely; however, through best management practices, this risk can be effectively managed and maximumly mitigated. Accurate and rapid detection of DON contamination as early in the entire value chain as possible is critical. To achieve this goal, we developed a DON test strip based on time-resolved fluorescence immunoassay (TRFIA) and a specific DON monoclonal antibody for the rapid quantification of DON in food crops and feeds. The strip displayed a good linearity (R 2 = 0.9926), with a limit of quantification of 28.16 μg/kg, a wide linear range of 50 ~ 10,000 μg/kg. The intra-batch coefficient of variation (CV) and the inter-batch CV was <5.00 and 6.60%, respectively. This TRFIA-DON test strip was applied to detect DON in real samples, and the accuracy and reliability were confirmed by liquid chromatography-mass spectrometry (LC-MS/MS). Results showed that the relative standard deviation between the DON strips and LC-MS/MS was <9%. The recovery rates in corn samples ranged from 92 to 104%. The established TRFIA-DON test strip had the characteristics of high sensitivity, high accuracy, and a wide linear range which was suitable for rapid and quantitative determination of DON in food crops and feeds at both on-site and laboratory.

Chronic kidney disease (CKD) is a global disease that is harder to treat at a later stage. Therefore, early diagnosis and monitoring of CKD are crucial. T cell immunoglobulin and mucin domain molecule 3 (Tim-3) is a negative regulator of the T cell responses and it is involved in the immunomodulation of kidney disease. To date, only a small number of reports regarding serum soluble Tim-3 (sTim-3) in CKD are available. In the present study, the serum levels of sTim-3 in patients with CKD at different stages and the levels of sTim-3 in the early diagnosis and monitoring of CKD were analyzed. A highly sensitive time-resolved fluorescence immunoassay was performed to quantify sTim-3 levels in 318 patients with CKD and 114 healthy individuals. The serum levels of sTim-3 in patients with CKD (33.47±20.77 ng/ml) were significantly higher than those in the healthy individuals group (8.32±3.23 ng/ml; P<0.0001). As CKD progressed from stage G1 to G5, the serum sTim-3 level gradually increased (P<0.0001). A cut-off value of 13.63 ng/ml for the sTim-3 concentration was effective in diagnosing patients with CKD (area under the receiver operating characteristic curve, 0.9176; sensitivity, 79.87%; specificity, 96.49%). At this critical value, the positive detection rate of CKD in the early stages (G1 + G2), G3, G4 and G5 was 55.70, 77.78, 84.44 and 92.86%, respectively. In conclusion, the serum sTim-3 levels in patients with CKD were significantly higher than those in the healthy individuals group. As CKD progressed from G1 to G5, the serum sTim-3 concentration gradually increased, facilitating the monitoring of the progression of CKD. In addition, serum sTim-3 had an auxiliary effect that was useful in the early diagnosis of CKD. The positive detection rate of CKD in the early stages was 55.70%, which can assist other clinically common kidney disease indicators.

UNASSIGNED: Viral hepatitis is a widespread and serious infectious disease, and most patients with liver cirrhosis and hepatocellular carcinoma are prone to viral infections. T cell immunoglobulin-and mucin-domain-containing molecule-3 (Tim-3) is an immune checkpoint molecule that negatively regulates T cell responses, playing an extremely important role in controlling infectious diseases. However, reports about the role of serum soluble Tim-3 (sTim-3) in hepatitis virus infection are limited. Therefore, this study explored changes in sTim-3 levels in patients infected with hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis E virus (HEV).
UNASSIGNED: This study applied high-sensitivity time-resolved fluorescence immunoassay for the detection of sTim-3 levels. A total of 205 cases of viral hepatitis infection (68 cases of HBV infection, 60 cases of HCV infection, and 77 cases of HEV virus infection) and 88 healthy controls were quantitatively determined. The changes in serum sTim-3 level and its clinical value in hepatitis virus infection were analyzed.
UNASSIGNED: Patients with HBV infection (14.00, 10.78-20.45 ng/mL), HCV infection (15.99, 11.83-27.00 ng/mL), or HEV infection (19.09, 10.85-33.93 ng/mL) had significantly higher sTim-3 levels than that in the healthy control group (7.69, 6.14-10.22 ng/mL, P < 0.0001). Patients with hepatitis and fibrosis infected with HBV (22.76, 12.82-37.53 ng/mL), HCV (33.06, 16.36-39.30 ng/mL), and HEV (28.90, 17.95-35.94 ng/mL) had significantly higher sTim-3 levels than patients with hepatitis without fibrosis (13.29, 7.75-17.28; 13.86, 11.48-18.64; 14.77, 9.79-29.79 ng/mL; P < 0.05).
UNASSIGNED: sTim-3 level was elevated in patients infected with HBV, HCV, or HEV and gradually increased in patients with either hepatitis or hepatitis with hepatic fibrosis. It has a certain role in the evaluation of the course of a disease after hepatitis virus infection.

To establish a rapid and highly sensitive assay for tumor-associated trypsinogen-2 (TAT-2) based on the time-resolved fluorescence immunoassay (TRFIA) and evaluate its potential clinical value in patients with lung cancer. The double-antibody sandwich method was used in detecting TAT-2 antigen concentrations, and two types of TAT-2 antibodies (coating antibodies and Eu3+ labeled antibodies) were used. A TAT-2-TRFIA method was then established, evaluated, and used in detecting the serum TAT-2 levels of healthy subjects and patients with lung cancer. The linear range of the TAT-2-TRFIA method was 1.53-300 ng/mL, the intra-assay coefficient of variation (CV) were between 1.67% and 8.42%, and the inter-assay CV were between 4.29% and 11.44%. The recovery rates of TAT-2-TRFIA were between 99.17% and 107.06%. The cross-reactivities of trypsin and T-cell immunoglobulin mucin 3 were 0.02% and 0.82%, respectively. The serum TAT-2 levels of patients with lung cancer were higher than those of healthy subjects (P < 0.001). Combined with TAT-2, the sensitivity and specificity of CEA and CA-125 for lung cancer improved significantly. Conclusion: We successfully established a highly sensitive TAT-2-TRFIA method, which was able to facilitate the timely diagnosis of lung cancer.

UNASSIGNED: The present study aimed to evaluate the clinical value of the combined detection of soluble T cell immunoglobulinand mucin domain molecule 3 (sTim-3) and pepsinogen (PG) in sera for gastric cancer (GC) diagnosis.
UNASSIGNED: The double antibody sandwich method was used to establish a highly sensitive time-resolved fluorescence immunoassay for the detection of sTim-3. Serum sTim-3, PGI, and PGII levels in 149 GC patients (123 first-diagnosis GC patients and 26 post-GC patients), 81 patients with benign gastric disease (BGD), and 73 healthy controls were quantitatively detected. The clinical diagnostic value of the combined detection of sTim-3 and PG in GC was analyzed.
UNASSIGNED: Serum sTim-3 levels in GC (20.41 ± 9.55 ng/mL) and BGD (16.50 ± 9.76 ng/mL) patients were significantly higher (P < 0.001) than those in healthy controls (9.22 ± 3.40 ng/mL). Combined detection of sTim-3 and PGI/PGII (AUC: 0.9330, sensitivity: 86.44%, and specificity: 91.78%) showed a high diagnostic value for GC. When the level of PGI/PGII was less than 12.11 and that of sTim-3 was greater than 14.30 ng/mL, the positive rate of the control group was reduced to 0%, and the positive detection rate of GC was 54.47%. In addition, in post-operative patients, serum sTim-3 levels in the recurrence group (33.56 ± 4.91 ng/mL) were significantly higher than those in the no recurrence group (11.95 ± 5.16 ng/mL).
UNASSIGNED: sTim-3 levels in BGD and GC sera were significantly higher than those in the control group sera. Additionally, sTim-3 serum levels can predict recurrence in post-operative patients. Compared with PG alone, the combined detection of serum PG and sTim-3 can significantly improve the detection sensitivity and specificity of BGD and GC.

Currently, atherosclerosis accounts for the majority of cardiovascular morbidity and mortality worldwide, and predicting the stability of atherosclerotic plaque is the main method to prevent atherosclerotic death. This study aims to establish a dual-label time-resolved fluorescence immunoassay (TRFIA) of matrix metalloprotein-9 (MMP-9) and lipoprotein-associated phospholipaseA2 (Lp-PLA2) to predict atherosclerotic plaque stability. A dual-label TRFIA was introduced for the simultaneous quantification of MMP-9 and Lp-PLA2 using fluorescent lanthanide (Eu3+ and Sm3+) chelates. The performance (sensitivity, specificity, accuracy, precision and reference intervals in different subjects) of this TRFIA was evaluated and compared with commercial kit. The sensitivity of the TRFIA for MMP-9 was 0.85 ng/mL and for Lp-PLA2 was 0.68 ng/mL with high affinity and specificity. The average recoveries were 94.58% to 109.82%, and 104.32% to 109.26%, respectively. All intra- and inter-assay CVs ranged from 3.10% to 5.46%. For the normal subjects, the cutoff value was 160.70 ng/mL for MMP-9 and 183.73 ng/mL for LP-PLA2; for the subjects with stable plaque, the cutoff value was 181.98~309.22 ng/mL for MMP-9 and 194.73~337.89 ng/mL for LP-PLA2; for the subjects with unstable plaque, the cutoff value was 330.43 ng/mL for MMP-9 and 343.23 ng/mL for LP-PLA2. This TRFIA detection results agreed well with the results of commercial kit (R2=0.9567 and R2=0.9771, respectively) in clinical serum samples. The TRFIA developed has a wide detection range and good sensitivity for the high-throughput simultaneous detection of MMP-9 and Lp-PLA2 in serum, which provides a new method for predicting the stability of atherosclerotic plaque.

BACKGROUND: The renal biopsy is an accurate and reliable gold standard for membranous nephropathy (MN) diagnosis. However, it is an invasive procedure involving the risk of hemorrhage or infection. Thus, an alternative approach that can facilitate the effective diagnosis and treatment monitoring of idiopathic membranous nephropathy (IMN) is urgently needed.
METHODS: We established a dual-labeled time-resolved fluoroimmunoassay (TRFIA) to simultaneously detect phospholipase A2 receptor (PLA2R)-IgG4 and PLA2R-IgG antibodies. Utilizing this assay, we determined the ratio of autoantibodies in the serum of patients with different kidney diseases and normal controls.
RESULTS: The sensitivity of TRFIA for detecting anti-PLA2R-IgG and anti-PLA2R-IgG4 was 0.12 µg/mL and 0.001 µg/mL, respectively. Human IgA did not interfere with the assay. Compared to anti-PLA2R-IgG alone, the positive rate of IMN could be increased from 86.5 % to 91.7 % through the combined use of anti-PLA2R-IgG4 and the PLA2R-IgG4/IgG ratio. In contrast, the false-positive rates for the detection of IgA nephropathy, lupus nephropathy, diabetic nephropathy, and minimal change nephropathy decreased from 25 to 50 % to 0 %.
CONCLUSIONS: The dual-labeled PLA2R-IgG4/IgG-TRFIA for simultaneous detection of anti-PLA2R-IgG4 and anti-PLA2R-IgG will contribute to improved accuracy of IMN diagnosis.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spreading rapidly around the world. Antibody detection plays an important role in the diagnosis of COVID-19. Here, we established a new time-resolved fluorescence immunoassay (TRFIA) to determine COVID-19 total antibodies. A double-antigen sandwich TRFIA was optimized and established: recombinant nucleocapsid phosphoprotein (N protein) and spike protein (S protein) of COVID-19 immobilized on 96-well plates captured human COVID-19 antibodies and then banded together with the N/S proteins labeled with europium(III) (Eu3+ ) chelates, and finally, time-resolved fluorometry was used to measure the fluorescence values. We successfully established a TRFIA method for the detection of human COVID-19 total antibodies, and the cutoff value was 2.02. There was no cross-reactivity with the negative reference of the National Reference Panel for IgM and IgG antibodies to COVID-19. The CV of the precision assay was 3.19%, and the assay could be stored stably for 15 days at 37°C. Compared with that of the colloidal gold method and chemiluminescence method, the sensitivity of the TRFIA method was higher, and the false positive/negative rate was lower. This established TRFIA has high sensitivity, accuracy, and specificity, which indicates that this method provides a new detection method for the high-throughput routine diagnosis of COVID-19.