Enzyme-linked Immunosorbent Assay Screening Research Articles

Combination of an enzyme-linked immunosorbent assay and an indirect fluorescence assay for a nationwide sero-survey of Toxoplasma gondii infection in pig herds in Taiwan

Toxoplasma gondii is a zoonotic pathogen that can infect farm animals, companion animals, and humans, sometimes causing public health issues. In Taiwan, the pig industry is a vital agricultural industry, with a self-sufficiency rate of 91 %, and pigs are also food-producing animal reservoirs of Toxoplasma gondii. Infected pigs are usually asymptomatic, and abortions and death may occur in severe cases. We combined an enzyme-linked immunosorbent assay (ELISA) and an indirect fluorescence assay (IFA) to investigate the seroprevalence of Toxoplasma gondii among pig populations in Taiwan. A stratified sampling approach to determine the number of sample farms proportional to the number of pig farms in each county was employed, with 15 blood samples collected at each farm between July and September 2017. With the tested results, empirical Bayesian smoothing was utilized to assess the proportion of Toxoplasma-positive farms at the county level. Bayesian mixed-effects logistic regression models, incorporating farm and county as random effects, were employed to investigate associations between Toxoplasma test results and potential risk factors. A total of 930 serum samples from 62 pig farms were collected and tested. An overall herd prevalence of 27.4 % was shown with the seroprevalence in northern Taiwan being greater than that in southern Taiwan. The sampling month and companion dog density in 2017 were significantly associated with Toxoplasma infections in pigs. With every increase in the number of companion dogs per km² at the county level, the odds of Toxoplasma infection in pigs increased by 4.7 % (95 % CI: 1.7–8.9 %). This study demonstrated that combining ELISA for screening with IFA for confirmation is a cost-effective and time-saving method for conducting a large-scale sample investigation. This was also the first nationwide, cross-sectional study in Taiwanese pig herds to investigate Toxoplasma gondii infection.

Prevalence of HBV Co-infections with HCV and HIV among Blood Donors in Ado-Ekiti, Ekiti State, Nigeria

Blood is a life-saving resource. Despite the significance of blood transfusion in saving a millions life in emergencies and medical treatment, the safety of blood transfusion faced challenges of transmitting life threatening transfusion transmissible infectious agents such as hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). The study was carried out to determine the sero-prevalence of HBV, HCV, HIV and co-infections among blood donors in Ado-Ekiti, Nigeria. A total of five hundred (500) prospective blood donors age ranged from 18 to 60 years attending Ekiti State University Teaching Hospital between May to November, 2019 were recruited for the study. Prospective study was based on questionnaires administered to generate socio-demographics and a 5ml venous blood samples were obtained from each blood donors and the plasma was used for determination of hepatitis B surface antigen (HBsAg) and anti-HCV using immunoassay rapid test kit (RTK) Diaspot, Belgium and HIV-1 and HIV-2 Determine Alere Medical ,Japan and further tested with enzyme linked immunosorbent assay (ELISA) Biorad Monolisa, France). The prevalence of HBV, HCV and HIV were 4.8%, 1.2% and 1.8% respectively, while co-infections with HBV/ HIV and HBV/HCV were 0.2% and 0.2% respectively and there was no case of triple infections among the blood donors. The incidence rate was high in HBV followed by HIV and HCV. The use of RTK and ELISA for screening of blood donor for HBsAg, anti HCV and HIV in terms of their sensitively and specificity showed that ELISA is more sensitive than RTK while RTK is more specific than ELISA. From the retrospective study age and gender distribution was not statistically significant (P > 0.05). A significance difference was observed between married blood donors and HIV infection (P < 0.05) and also blood donors with history of blood transfusion showed statistical significant to HBV and HCV (P < 0.05). The prevalence of HBV, HCV and HIV infections among blood donors were found to be statistically associated with smoking, alcohol consumption, surgical operation, multiple sex partners and tattooing (P < 0.05). This study shows that the prevalence of HBV infection in Ado-Ekiti, Ekiti State ,Nigeria was higher than HCV and HIV, hence there is need to increase public awareness of the socio-cultural practices that contribute to the transmission of infection.

The first evidence of bovine viral diarrhea virus circulation in Libya.

Bovine viral diarrhea (BVD) is endemic in North Africa and the Mediterranean Basin with high socioeconomic impacts. However, there are no data on this disease in Libya. One of the aims of this study was to provide data on BVD in Libya, to fill in the gap in the region and to investigate the level of seroprevalence of BVD virus (BVDV) in Libya and associated risk factors. A total of 1599 serum samples were collected from cattle herds belonging to seven Libyan regions. All sera were assayed using a screening enzyme-linked immunosorbent assay for the detection of antibodies against BVDV. The overall seroprevalence of BVDV was estimated to be 48.6% (95% confidence interval, 46.08%-50.98%). A seroprevalence rate of 36.8% was detected in cattle aged <1 year, 41.0% in cattle aged between 1 and 2 years, and 49.7% in cattle aged >2 years. Statistically significant differences (p = 0.001) were observed between age groups. BVDV seroprevalence was significantly associated with geographical region (p = 0.033). To the best of our knowledge, this is the first study on BVD in Libya, and the results suggest that BVD is endemic in Libya. Further studies are required to isolate and characterize the circulated BVDV in Libya.

The Interleukin-15 and Interleukin-8 Axis as a Novel Mechanism for Recurrent Chronic Rhinosinusitis with Nasal Polyps.

The prevention of postoperative recurrence after endoscopic sinus surgery (ESS) relies on targeting specific pathological mechanisms according to individuals' immunological profiles. However, essential biomarkers and biological characteristics of difficult-to-treat chronic rhinosinusitis (CRS) patients are not well-defined. The aim of this study was to explore the immunologic profiles of subgroups of CRS patients and determine the specific cytokines responsible for recalcitrant or recurrent CRS with nasal polyposis (rCRSwNP). We used 30 cytokine antibody arrays to determine the key cytokines related to recurrent polypogenesis. Enzyme-linked immunosorbent assay (ELISA) experiments were conducted to assess the levels of these key cytokines in 78 patients. Polymorphonuclear leukocytes (PMNs) isolated from nasal polyps were challenged with specific cytokines to examine the levels of enhanced interleukin (IL)-8 production. Finally, we used immunohistochemistry (IHC) staining to check for the presence and distribution of the biomarkers within nasal polyps. A cytokine antibody array revealed that IL-8, IL-13, IL-15, and IL-20 were significantly higher in the recalcitrant CRSwNP group. Subsequent ELISA screening showed a stepwise increase in tissue IL-8 levels in the CHR, CRSsNP, and CRSwNP groups. PMNs isolated from nine CRSwNP cases all demonstrated enhanced IL-8 production after IL-15 treatment. IHC staining was labeled concurrent IL-8 and IL-15 expression in areas of prominent neutrophil infiltration. Our results suggest that IL-15 within the sinonasal mucosa plays a crucial role in promoting IL-8 secretion by infiltrating PMNs in recalcitrant nasal polyps. In addition, we propose a novel therapeutic strategy targeting the anti-IL-15/IL-8 axis to treat CRS with nasal polyposis.

Clinical significance of viral markers testing by ELISA and Individual Donation Nucleic Acid Testing (ID-NAT) for blood screening in blood bank: Single center study in Egypt

Prevention of transfusion-transmitted viral infections and insurance of safe blood transfusion are the main goals of all blood banks worldwide. Despite the high sensitivity and specificity of currently used enzyme linked immunosorbent assay (ELISA) for hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) testing, viral transmission could still occur during the window period. Introducing viral individual donation nucleic acid testing (ID-NAT) can greatly decrease such risk providing an additional layer in securing blood transfusion. We aimed to assess the clinical significance of viral markers testing by ELISA and ID-NAT for blood screening in the Blood Bank of Suez Canal University Hospital. We studied all donations (2132) collected during a two-months period. Blood donor samples were screened by ELISA and ID-NAT tests for HBV, HCV, and HIV. Serological testing results for HCV by ELISA revealed 2,122 (99.5 %) negative donations compared to 2,131 (99.95 %) negative donations by ID-NAT testing. Of the positive ELISA samples, only one was NAT positive. For HBV ELISA testing, 2,115 (99.2 %) donations were negative, also by ID-NAT testing 2,115 (99.2 %) donations were HBV DNA negative. Out of the negative ELISA samples, two samples were ID-NAT reactive donors which were missed by serology assay being in the window period. HIV ELISA testing revealed negative 2,130 (99.9 %) donations while ID-NAT testing showed 2,131 (99.95 %) negative donations and one positive donation. In conclusion, this is the first study carried out in the Suez Canal and Sinai region, Egypt to assess the importance of ID-NAT implementation. The introduction of ID-NAT in blood banks is an effective method for increasing safety of the blood transfusion.

Generation and characterization of mAb 61H9 against junctional adhesion molecule-a with potent antitumor activity.

Junctional adhesion molecule-A (JAM-A) is an adhesion molecule that exists on the surface of certain types of cells, including white blood cells, endothelial cells, and dendritic cells. In this study, the cDNA sequences of JAM-A-Fc were chemically synthesized with optimization for mammalian expression. Afterward, we analyzed JAM-A protein expression through transient transfection in HEK293 cell lines. Mice were immunized with JAM-A-Fc protein, and hybridoma was prepared by fusing myeloma cells and mouse spleen cells. Antibodies were purified from the hybridoma supernatant and four monoclonal strains were obtained and numbered 61H9, 70E5, 71A8, and 74H3 via enzyme-linked immunosorbent assay screening. Immunofluorescence staining assay showed 61H9 was the most suitable cell line for mAb production due to its fluorescence signal being the strongest. Flow cytometric analysis proved that 61H9 possessed high affinity. Moreover, antagonism of JAM-A mAb could attenuate the proliferative, migrative, and invasive abilities of ESCC cells and significantly inhibit tumor growth in mice. By examining hematoxylin-eosin staining mice tumor tissues, we found inflammatory cells infiltrated lightly in the anti-JAM-A group. The expression of BCL-2 and IκBα in the anti-JAM-A group were decreased in mice tumor tissues compared to the control group. Ultimately, a method for preparing high-yield JAM-A-Fc protein was created and a high affinity mAb against JAM-A with an antitumor effect was prepared.

Performance of Enzyme Linked Immunosorbent Assay and Rapid Screening Techniques for detection Of Transfusion Transmitted Infections among blood donors

Introduction: Blood transfusion is associated with many risks, especially exposure to a transfusion-transmitted infections (TTIs). Lack of effective diagnostic techniques that can identifying the infection at window period contributes to the major health problem in most developing countries. The aim of this study was to compare diagnostic performance of enzyme linked immunosorbent assay (ELISA) and rapid screening techniques for detection of transfusion-transmitted infections (TTIs) among blood donors Methodology: This study was conducted in the Department of Haematology and Blood Transfusion Services Federal Teaching Hospital, Ido-Ekiti, Nigeria from February 2021 to July 2023. A total of 3150 eligible blood donors that were screened fit for blood donation using rapid kits were subjected to ELISA screening technique. Questionnaire was used to inquire about risk factors for transfusion transmissible infection among blood donors and to sort the consent of all the blood donors before collecting their blood sample for study Result: A total of 3150 blood donors that were screened negative for TTIs (HbsAg, HCV, HIV and syphilis) by rapid test kits were recruited for the study. Out of 3150 blood donors that were re-screened for TTIs by ELISA techniques, 34 (1.08%), 50 (1.59%), 07 (0.22%) and 13 (0.41%) were sero-positive for HbsAg, HCV, HIV and syphilis respectively. In general, the percentage seroprevalence of TTIs in our study was 104/3150 (3.3%), HCV had the highest prevalence of TTIs and Blood group O Rh D positive has the highest frequency among the study population Conclusion: This study concluded that rapid test did not show any promising results when compared to ELISA. This study suggested that rapid test kits should not be recommended in transfusion center solely for screening blood donors for TTIs. There is need for combination of rapid test kits along with ELISA technique in the diagnosis of TTIs for blood donors. We advocate for legislation to make screening with ELISA mandatory for TTIs in all blood transfusion center and other health facilities in the country

Canine distemper virus (CDV)-neutralizing activities of an anti-CDV canine-derived single-chain variable antibody fragment 4-15 (scFv 4-15) screened by phage display technology

Canine distemper virus (CDV) is a highly contagious pathogen that causes severe diarrhea, fever and vomiting in domestic dogs, posing a serious threat to the dog breeding industry. Currently, there are no effective therapeutic agents for emergency treatment despite the availability of vaccines against CDV infection. Single-chain fragment variable (scFv) antibody has been demonstrated to effectively inhibit virus infections, suggesting a potential candidate as a therapeutic agent for canine distemper. In this study, a phage-displayed scFv library was constructed from the peripheral blood lymphocytes of dog immunized intramuscularly with live-attenuated CDV vaccine, and was subjected to four rounds of pannings against CDV. Subsequent indirect enzyme-linked immunosorbent assay screening revealed high-affinity scFv antibodies specific to CDV, and indirect immunofluorescence assay screening revealed CDV-neutralizing activity of scFv antibodies. Our results showed that a scFv antibody 4–15 (scFv 4–15) with high-affinity binding to CDV and neutralizing activity against CDV was obtained, which displayed effective therapeutic potential in vivo for dogs challenged with a lethal dose of CDV. Conclusively, the scFv 4–15 with high-affinity binding and neutralizing activity to CDV that was obtained by phage display technology provides a promising candidate for the therapeutic agents against CDV infection.

Analysis of the reentry status of blood donors with reactive bloodborne pathogen screening markers in Hangzhou City

Objective: To explore the reentry rate of reactive blood donors in the bloodborne pathogen infection screening in Hangzhou City, and analyze the donation behavior of those who successfully returned. Methods: A retrospective analysis of the return data of blood donors with reactive bloodborne pathogen screening markers was conducted at Zhejiang Provincial Blood Center from June 2017 to May 2022. The reentry process for blood donors with reactive bloodborne pathogen screening markers in Hangzhou City is as follows: after the initial screening period of 6 months, donors can voluntarily apply for return to the blood center. Samples are collected and subjected to routine enzyme-linked immunosorbent assay (ELISA) screening for HBsAg, anti-HCV, HIV Ab/Ag, and anti-TP, as well as a single nucleic acid (HIV/HCV/HBV) test. For samples that show non-reactivity in both ELISA and nucleic acid tests, serum biomarker testing for the reasons of exclusion is performed using chemiluminescence immunoassay (CLIA), and those with non-reactivity are allowed to return. Results: A total of 4 583 reactive blood donors who met the criteria for re-entry applied for reentry, out of which 475 applications were received from donors in the Hangzhou area. Among these, 279 donors were successfully readmitted, resulting in a success rate of 58.74% (279/475). By the end of December 2021, out of the 174 donors who successfully returned, 114 donors chose to donate again. They collectively donated 39 530 ml of whole blood and 1 147.2 therapeutic doses of platelets. Among these, 21 donors once again showed reactivity for pathogen infection biomarkers, accounting for 18.42% (21/114). Conclusion: The reentry strategy has somewhat mitigated the attrition of blood donors. Nevertheless, there are instances where donors who were successfully readmitted show reactivity once more in the screening for pathogen infection biomarkers.

The use of cathepsin L1 (FhCL1) serological ELISA in sentinel screening for liver fluke on sheep farms.

Fasciola hepatica is a parasitic helminth (worm) that poses a significant economic threat to the ruminant livestock industry worldwide. The disease, fasciolosis, can result in a range of clinical signs including anaemia, weight loss and death, with the most severe symptoms attributed to early acute infection when the parasite is migrating through the liver. Early diagnosis and intervention are essential for the control and management of the disease to prevent productivity losses. The traditional gold standard method of diagnosis uses faecal egg counts (FEC) that is limited to detecting patent infections from 10 to 12weeks post infection (WPI). In contrast, serological assays can detect pre-patent infections as we have shown that enzyme-linked immunosorbent assays (ELISA) using the F. hepatica cysteine peptidase cathepsin L1 (FhCL1) can detect liver fluke infections from 3 to 4 WPI. Here, we used FEC and ELISA to monitor liver fluke infections in sentinel lambs from three commercial farms in Ireland from September 2021 to March 2022. All three farms showed a significant increase in FhCL1 antibody levels and FEC over this time, with a substantial rise in positive infection detection between late November and January. However, ELISA screening detected infection at least two months prior to FEC (September). This suggests that the regular screening of sentinel lambs for F. hepatica seroconversion in a "test and treat" approach could mitigate the negative damaging impact of early fasciolosis on flock health, welfare and productivity and inform management strategies. In addition, we show that whole blood samples taken on Whatman® protein saver cards could replace conventional serum blood tubes for blood collection. Cards can be stored at room temperature for long periods of time and samples revisited at any time for re-analysis. The adoption of these cards on farm together with the FhCL1 ELISA would provide a simpler, cost-effective, and eco-friendly method for testing sentinel lambs for liver fluke disease.

High-Throughput CD36 Phenotyping on Human Platelets Based on Sandwich ELISA and Mutant Gene Analysis

Background: CD36 deficiency is closely associated with fetal/neonatal alloimmune thrombocytopenia, platelet transfusion refractoriness, and other hemorrhage disorders, particularly in Asian and African populations. There is a clinical need for rapid and high-throughput methods of platelet CD36 (pCD36) phenotyping to improve the availability of CD36 typing of donors and assist clinical blood transfusions for patients with anti-CD36 antibodies. Such methods can also support the establishment of databases of pCD36-negative phenotypes. Study Design and Methods: A sandwich enzyme-linked immunosorbent assay (ELISA) for CD36 phenotyping of human platelets was developed using anti-CD36 monoclonal antibodies. The reliability of the assay was evaluated by calculating the intra-assay and inter-assay coefficients of variation (CV). A total of 1,691 anticoagulant whole blood samples from healthy blood donors were randomly selected. PCD36 expression was measured using a sandwich ELISA. PCD36 deficiency was confirmed by flow cytometry (FC). Mutations underlying pCD36 deficiency were identified using polymerase chain reaction sequence-based typing (PCR-SBT). Results: The sandwich ELISA for pCD36 phenotyping had high reliability (intra-assay CV, 2.1–4.8%; inter-assay CV, 2.3–5.2%). The sandwich ELISA was used to screen for CD36 expression on platelets isolated from 1,691 healthy blood donors. Of these, 36 samples were pCD36-negative. FC demonstrated absence of CD36 expression on monocytes in three of the 36 cases. In the present study population, the frequency of CD36 deficiency was 2.13% (36/1,691), of which 0.18% (3/1,691) was type I deficiency and 1.95% (33/1,691) was type II deficiency. In addition, we used PCR-SBT to characterize the gene mutations in exons 3–14 of the CD36 gene in 27 cases of CD36 deficiency and discovered 10 types of mutations in 13 pCD36-negative samples. Conclusion: The present study describes the development and characterization of a highly reliable sandwich ELISA for high-throughput screening for pCD36 expression. This novel method is feasible for clinical applications and provides a useful tool for the establishment of databases of pCD36-negative phenotype donors.

Cerebral venous sinus thrombosis associated with SRA-negative heparin-induced thrombocytopenia: case report

BackgroundThere are very few documented reports in literature of cerebral venous sinus thrombosis (CVST) caused by immune-mediated heparin-induced thrombocytopenia (HIT). Further, there are very few reports of false negative serotonin release assays (SRAs) when testing for immune-mediated HIT.Case presentationWe present a case of a 60- year-old male with recent unfractionated heparin administration for venous thromboembolism prophylaxis, an elevated 4T score of 5 and acute CVST in which immune-mediated HIT was suspected. The enzyme-linked immunosorbent assay (ELISA) screening assay was positive for PF4 antibodies and subsequent reflexive SRA testing was negative. However, given the clinical picture, a false-negative SRA was suspected (and eventually confirmed), prompting use of the alternative PF4-dependent p-selectin expression assay (PEA) which was confirmed to be positive. The patient was successfully managed with a bivalirudin infusion and eventually transitioned to apixaban.ConclusionIt is uncommon for immune-mediated HIT with thrombosis to manifest as CVST. Similarly, false-negative SRA is uncommon in immune-mediated HIT. Take-away lessons from our case report include considering HIT in CVST patients with an elevated 4T score and considering the entire clinical picture and degree of suspicion for HIT when interpreting negative HIT testing results. The PEA, in conjunction with the 4Ts score, may be considered as an alternate diagnostic assay for HIT.

IMPLEMENTATION OF THE SYSTEM OF HONEY SAFETY CONTROL ON THE EXAMPLE OF ANALYZING OF RESIDUES OF TETRACYCLINE GROUP ANTIBIOTICS

The National Reference Laboratory of Drug Residues Control has implemented a system of "classical" honey safety control based on the parameters of antimicrobial drug residues: samples testing by the screening enzyme-linked immunosorbent assay (ELISA) method and, in the case of positive or possibly positive samples occurring, – retesting by confirmatory UPLC-MS/MS multi-method developed in the laboratory. The article presents the results of ELISA screening method validation for the determination of residual amounts of tetracycline group antibiotics (tetracycline, oxytetracycline, chlortetracycline, doxycycline) in honey samples using Tetracyclin® RIDASCREEN test kits by R-Biopharm (Germany) and Oxytetracycline ELISA by EuroProxima (the Netherlands) and its verification by means of the confirmatory method.&#x0D; In accordance with the Commission Implementing Regulation (EU) 2021/808, the validation of test kits proposed by the manufacturers was carried out taking into account the minimum required limit of detection. The fitness-for-purpose of the methods was confirmed based on the establishment of main validation parameters for screening methods (technical threshold and cut-off factor) using control (blank) and fortified honey samples with standard solutions of tetracycline at the level of ½ of the minimum required limit of detection, according to the "added-received" criterion. The proposed methods are the simple in carrying out, time- and cost-effective, which are their main advantages.&#x0D; The reliability of the results obtained by the proposed methods was verified using the developed confirmatory UPLC-MS/MS multi-method. The results of comparative studies of control (blank) honey samples and fortified with a standard solution of tetracycline antibiotics at the level of 2.5 and 5.0 μg/kg, as well as the results of the interlaboratory testing with the accredited laboratory (Germany) are presented.

Anti-tissue Transglutaminase Enzyme-Linked Immunosorbent Assay for Screening of Celiac Disease in Moroccan Pediatric Patients

Celiac disease (CD) is an immune-mediated systemic disorder elicited by gluten which induces an enteropathy with atrophy of intestinal villi. No prevalence information was available for CD in Moroccan children because the diagnosis is based on multiple invasive duodenal biopsies. To simplify CD diagnosis, the objective of this work was to develop an Enzyme-linked Immunosorbent Assay (ELISA) for IgA and IgG tissue transglutaminase (tTG) antibodies detection suitable for Moroccan children. The concentration of the coated antigen and serum dilutions were optimized for the development of IgA anti- tTG and IgG anti-tTG ELISA detection in serum. The cut-off was calculated and the developed ELISAs were used for detecting IgA and IgG-tTG antibodies in 97 serum samples from 97 children aged 1 to 13 years, with variable clinical characteristics. After adjusting optimal working conditions of ELISA, the cut-offs were 0.04 and 0.156 AU for detecting anti-tTG and IgA anti-tTG IgG respectively. The use of IgG anti-tTG as CD marker (100 % of sensitivity) was better than the use of IgA anti-tTG in ELISA tests (90.3% sensitivity). In addition, the ELISA test shows a clear correlation between the IgG tTG antibodies titer and the degree of duodenal damage, estimated by the Marsh stages classification in patients with confirmed CD. Our results suggest that the assessment of the adapted IgG anti-tTG ELISA test can be used for CD in initial screening in Moroccan children after validation with a larger number of samples with CD for confirmation.

Heterologous-coating antigen enhancing the sensitivity of enzyme-linked immunosorbent assay for detection of mebendazole residues

The heterologous strategy could improve the sensitivity of competitive enzyme-linked immunosorbent assay (ELISA) for detection of chemical contaminants in food samples. In this study, the heterologous coating antigen ELISA was developed to evaluate its sensitivity for mebendazole (MBZ). Results showed that the heterologous ELISA had a linear range of (IC20–IC80) 0.34–10.54 ng/mL, an IC50 value of 1.83 ng/mL, and a limit of detection (LOD) of 0.13 ng/mL, in which the sensitivity of ELISA improved 1.7- and 2-fold (IC50 value dropping from 7.41 and 3.65 ng/mL to 4.27 and 1.83 ng/mL) than that of rabbit IgG- and chicken IgY-based homologous ELISA for MBZ, respectively. The heterologous coating antigen ELISA showed negligible cross reactivity (<0.2%) with its structural analogues, including hydroxy-MBZ, albendazole, oxfendazole, fenbendazole, and flubendazole, except the value of 72.6% for amino-MBZ. The average recoveries of MBZ spiked in pork and chicken muscle samples by the assay ranged from 83.7% to 109.8% and agreed well with those of high-performance liquid chromatography. The results suggested that using heterologous coating antigen could distinctly improve the sensitivity of ELISA for routine screening of MBZ residues in food samples.

Reduction in seroprevalence of viral transfusion-transmitted infections in southwest Nigeria in children with sickle cell disease using an enhanced screening strategy.

Blood transfusion is an integral component in the management of children and adults with sickle cell disease (SCD). Concerns about blood safety due to the high risk of bloodborne infections in sub-Saharan Africa limits the application of this cost-effective strategy in the management of individuals with SCD. In a single-centre, retrospective, longitudinal study in southwest Nigeria, we hypothesised that the use of stringent blood donor selection, along with very sensitive enzyme-linked immunosorbent assay (ELISA) screening methods would reduce transfusion-transmitted infections (TTIs). Among 45 002 eligible blood donors at the Lagos University Teaching Hospital in Nigeria, over a 5-year review period (2015-2019), the seroprevalence rate of viral TTIs was 9.83%. The seroprevalence rates for human immunodeficiency, hepatitis B, and hepatitis C viruses were 1.37%, 6.2%, and 2.25% respectively. Among 172 children with SCD, 71% (122/172) on regular blood transfusion and 29% (50/172) who had never been transfused or had less than two transfusions per lifetime, none acquired any TTIs using our enhanced screening approach during the study period. Thus, safe blood transfusion practices can be provided for children with SCD in sub-Saharan Africa with the use of stringent donor selection protocols and fourth-generation ELISA kits for TTI screening.

Intravenous immunoglobulin infusion contributes to a high incidence of false reactive screen results for human T-lymphotropic virus

Intravenous immunoglobulin (IVIg) has been increasingly used to treat immunodeficiencies and inflammatory disorders. However, IVIg has also been shown to affect a wide range of laboratory testing, including human T-lymphotropic virus (HTLV) screening. Our laboratory frequently observes false reactive HTLV screens from patients receiving IVIg infusions, however the extent of IVIg contribution to the false reactivity has not been extensively investigated. The objective of this study was to explore the prevalence of HTLV-1/2 infection in patients from the Sydney metropolitan area and evaluate the positive predictive value for HTLV screening test in sera from patients with or without IVIg infusions. HTLV screening test results from sera of 3843 patients referred to Central Sydney Immunology Laboratory between June 2006 and May 2021 were retrospectively analysed. Among 72 (1.9%) sera reactive on screening enzyme-linked immunosorbent assay (ELISA), 62 (86.1%) were from patients receiving IVIg infusions, including 60 collected post-IVIg and two collected pre-IVIg infusions. Only two (3.3%) of the 60 post-IVIg sera were positive on confirmatory western blot. In contrast, in non-IVIg sera, five (50.0%) from the 10 screen-reactive sera were positive on western blot. If positive western blot is used as the reference for determining 'true' HTLV infection, we found the positive predictive value of HTLV screening ELISA in sera collected post-IVIg (3.3%) is considerably lower than that in non-IVIg and pre-IVIg sera (41.7%). The vast majority of false reactive screen results (89.2%) in our study cohort were from sera collected post-IVIg infusion. Our study suggests that the high incidence of falsely reactive results in HTLV screening ELISA could be attributed to IVIg infusion. Hence, collection of sera from patients on IVIg should be avoided and screen-reactive results should be interpreted with greater caution, particularly for patients from non-endemic areas.

Evaluation of tetracycline antibiotics residues in chicken tissues using the four-plate test, ELISA, and HPLC methods in Iran

ABSTRACT Nowadays, various antibiotics are widely used for preventing and treating several diseases and for promoting growth in food-producing animals in different countries of the world. In this assay, edible chicken meat from local markets of Hamadan, a Province of Iran, was examined for residues of tetracycline antibiotics (tetracycline, oxytetracycline and chlortetracycline). In total, 150 samples of breast, wings and thigh tissue were randomly obtained from the local markets of the city of Hamadan. Four-plate tests (FPT), the enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC) were used to analyse tetracycline antibiotic (TC) residues, respectively. Results showed that out of 150 samples, 30 samples (24.00%) and 22 samples (14.71%) of carcases were positive or “suspect by antibiotic residues by FPT and ELISA screening method, respectively. The HPLC assay indicated in 7 samples of wings and 12 samples of breast and 18 samples of thigh, residues of TCs were detected. The study revealed that the TCs levels in one sample of wings and three samples of breast and five samples of thigh exceeded the maximum residue level (MRL) reported by the EU. To reduce the TC residues found in edible chicken meat, regulatory authorities should ensure that the chicken would undergo the proper withdrawal period from TCs before slaughtering.

A Comparison of Rapid Screening Test and ELISA for the Diagnosis of Hepatitis B Surface Antigen in Patients Attending a Tertiary Care Hospital, Tamil Nadu, India

Introduction: Hepatitis B virus infection is a major public health problem and leading cause of death worldwide. World Health Organisation (WHO) estimates that in 2015 about 257 million population were living with chronic Hepatitis B virus infection with a global prevalence of 3.5%. Among the several viral antigens of Hepatitis B, Hepatitis B Surface Antigen (HBsAg) is an important viral antigen which is recognised as a superior marker for Hepatitis B virus detection. For proper diagnosis of infection as well as disease management and prevention, identification of appropriate test kit is necessary. Aim: To compare the results of rapid screening tests and ELISA for the diagnosis of HBsAg. Materials and Methods: A cross-sectional study was conducted from July 2019-August 2019 in a tertiary care hospital. A total of 200 blood samples received for HBsAg testing were centrifuged. Serum of all the 200 blood samples were tested for HBsAg using both rapid Immuno Chromatographic Card (ICT) method (HEPAVIEW - one step test for HBsAg, Viola Diagnostic System, A Division of Tulip Diagnostics Pvt., Ltd.) and Enzyme Linked Immuno Sorbent Assays (ELISA) (Merilisa HBsAg- Meril Diagnostics Pvt., Ltd.) method. Data for rapid card method and ELISA were noted and entered into MS excel spread sheet and analysed. Results: Among the total 200 blood samples tested by HbsAg rapid card, five samples were positive and the remaining 195 were negative. For rapid card test, the sensitivity was 83.4%, specificity 100%, Positive Predictive Value (PPV) 100% and Negative Predictive Value (NPV) 99.4% and for ELISA the sensitivity, specificity, PPV and NPV were all 100%. Conclusion: The overall performance of the rapid ICT for HBsAg was less sensitive to ELISA. So, only ELISA can be encouraged in all setups irrespective of their developmental and economical status not only to prevent the complications of Hepatitis B infection but also for early diagnosis and better treatment of patients.

Incidence of Zika Virus Infection from a Dengue Epidemiological Study of Children in Ratchaburi Province, Thailand.

Zika virus (ZIKV) is the mosquito-transmitted virus that the WHO declared a Public Health Emergency of International Concern in 2016 due to the consequence of microcephaly from infected pregnancies. The incidence of Zika infection has been unclear in many countries because most infected people have nonspecific febrile illnesses. This study’s aim is to investigate the incidence of symptomatic Zika virus infections from the archived samples of a dengue cohort study of children in central Thailand from 2006 to 2009. We performed Zika NS1 immunoglobulin (Ig)G enzyme-linked immunosorbent assay (ELISA) screening to identify symptomatic Zika infections in paired acute/convalescent serum samples. Symptomatic Zika infections were confirmed by reverse transcription polymerase chain reactions (RT-PCR) of acute serum samples. The comparison of the Zika NS1 IgG ELISA results between acute and convalescent samples showed 290/955 (30.4%) seropositive cases. Zika RT-PCR results were positive in 28 febrile cases (15 females, 13 males). Zika RT-PCR showed that symptomatic Zika infection occurred in children aged 4–11 years in Ratchaburi province, Thailand (2007–2009, first case in April 2007), and the symptomatic Zika:dengue infection ratio was 28 Zika:394 dengue (1:14). Phylogenetic analysis showed that all Zika viruses were of Asian lineage. Zika NS1 IgG ELISA identified Zika-infected patients and showed a low Zika:dengue ratio.