Assay For Detection Of Antibodies Research Articles

Amplified suspension magnetic bead-based assay for sensitive detection of anti-glycan antibodies as potential cancer biomarkers

The development of a novel SUspension Magnetic-Bead-based Assay (SUMBA) for the detection of antibodies against aberrant glycans (AGA) as potential cancer biomarkers is presented here. The SUMBA method was extensively optimised by choosing proper commercially available AGA able to specifically, and with high affinity, recognise aberrant glycans, which were attached to the protein backbone working as a molecular scaffold (a glycoconjugate). The whole SUMBA was optimised using several analytical techniques such as Surface Plasmon Resonance and Energy Dispersive X-ray Spectroscopy. Additionally, the SUMBA method was extensively optimised for signal enhancement. With all steps optimised, we were able to detect AGA ultrasensitively with a limit of detection of 0.45 pM. Moreover, AGA could be detected in serum samples with a recovery index in the range of 98%–104%.

Comparative performance of WANTAI ELISA for total immunoglobulin to receptor binding protein and an ELISA for IgG to spike protein in detecting SARS-CoV-2 antibodies in Kenyan populations.

Many SARS-CoV-2 antibody detection assays have been developed but their differential performance is not well described. In this study we compared an in-house (KWTRP) ELISA which has been used extensively to estimate seroprevalence in the Kenyan population with WANTAI, an ELISA which has been approved for widespread use by the WHO. Using a wide variety of sample sets including pre-pandemic samples (negative gold standard), SARS-CoV-2 PCR positive samples (positive gold standard) and COVID-19 test samples from different periods (unknowns), we compared performance characteristics of the two assays. The overall concordance between WANTAI and KWTRP was 0.97 (95% CI, 0.95-0.98). For WANTAI and KWTRP, sensitivity was 0.95 (95% CI 0.90-0.98) and 0.93 (95% CI 0.87-0.96), respectively. Specificity for WANTAI was 0.98 (95% CI, 0.96-0.99) and 0.99 (95% CI 0.96-1.00) while KWTRP specificity was 0.99 (95% CI, 0.98-1.00) and 1.00 using pre-pandemic blood donors and pre-pandemic malaria cross-sectional survey samples respectively. Both assays show excellent characteristics to detect SARS-CoV-2 antibodies.

A High-throughput Automated ELISA Assay for Detection of IgG Antibodies to the SARS-CoV-2 Spike Protein.

The SARS-CoV-2 pandemic and vaccination campaign has illustrated the need for high throughput serological assays to quantitatively measure antibody levels. Here, we present a protocol for a high-throughput colorimetric ELISA assay to detect IgG antibodies against the SARS-CoV-2 spike protein. The assay robustly distinguishes positive from negative samples, while controlling for potential non-specific binding from serum samples. To further eliminate background contributions, we demonstrate a computational pipeline for fitting ELISA titration curves, that produces an extremely sensitive antibody signal metric for quantitative comparisons across samples and time.

Novel Synthetic Peptide-based Enzyme Linked Immunosorbent Assay for Antibody Detection in Viral Infections of the Central Nervous System

Introduction: Viral infections of Central Nervous System (CNS) are associated with severe neurological sequelae and can lead to significant morbidity if not adequately diagnosed and treated. An immunological assay detecting antibodies in the Cerebrospinal Fluid (CSF) of the patients is widely used for diagnosis of viral infections of the CNS. In the present study, diagnostic efficacy of in-house designed synthetic peptide based Enzyme Linked Immunosorbent Assay (ELISA) was evaluated for detection of antibodies against neurotropic viruses panel such as Cytomegalovirus (CMV), Epstein-Barr virus (EBV), Varicella Zoster Virus (VZV), Japanese Encephalitis Virus (JEV), Dengue (DENV), West Nile Virus (WNV) and Chandipura Virus (CHPV) in CSF of suspected cases. Aim: To determine the diagnostic efficacy of in-house developed synthetic peptide-based ELISA in viral infections of the CNS. Materials and Methods: A retrospective study was conducted in Central India Institute of Medical Science, Nagpur, Maharashtra, India. The suspected case of CNS viral infections of the patients were enrolled in this study from January 2013 to December 2015. Total 150 suspected cases of viral CNS infections and 135 control cases were recruited. Total 32 synthetic peptides of highly immunogenic proteins of respective seven neurotropic viruses were designed and synthesised. The designed peptides were evaluated in CSF samples of both the viral CNS infections and control cases for detection of Imunoglobulin G (IgG) and IgM antibodies using in-house developed antibody detection method. The developed tests were further compared with commercially available antibody detection ELISA kit. The sensitivity and specificity of peptide-ELISA were determined by Receiver Operating Curve (ROC) analysis and p-value was calculated by comparison of means by t-test. Results: Out of total 150 cases of CNS viral infections, a total of 31 CSF samples including 15 for CMV and 16 of JEV were positive by in-house peptide ELISA. The synthetic peptides STGDVVDISP, KQKSLVEL, RTLEVFKE, RSSNVED of CMV and ITYECPK, RRSVSVQT, GESSLVN of JEV showed a significant difference in mean absorbance value for IgM and IgG antibodies in CSF of suspected cases of viral CNS infection. Conclusion: The results demonstrated that the synthetic peptide-based ELISA is rapid, cost-effective, simple and efficient immunodiagnostic assay for initial screening of viral CNS infection.

Evaluation of Measles Igm Antibody Detection Assays During the 2018-2019 Outbreak in New York State

Evaluation of Measles Igm Antibody Detection Assays During the 2018-2019 Outbreak in New York State

Improved solid-phase competition enzyme-linked immunosorbent assay for the specific detection of antibodies against porcine parvovirus based on VP2 protein expressed in baculovirus

Improved solid-phase competition enzyme-linked immunosorbent assay for the specific detection of antibodies against porcine parvovirus based on VP2 protein expressed in baculovirus

Evaluation of recombinant glutathione transferase 26 kDa, thioredoxin-1, and endophilin B1 of Taenia solium in the diagnosis of human neurocysticercosis

Neurocysticercosis caused by Taenia solium larvae is a neglected disease that persists in several countries, including Mexico, and causes a high disability-adjusted life year burden. Neuroimaging tools such as computed tomography and magnetic resonance imaging are the most efficient for its detection, but low availability and high costs in most endemic regions limit their use. Serological methods such as lentil lectin-purified glycoprotein enzyme-linked immunoelectrotransfer blot antibody detection and monoclonal antibody-based enzyme-linked immunosorbent assays for HP10 antigen detection have been useful in supporting the diagnosis of this disease. We evaluated three T. solium recombinant antigens: glutathione transferase of 26 kDa (Ts26GST); thioredoxin-1 (TsTrx-1), and endophilin B1 (TsMEndoB1) by EITB. These are antigenic proteins antigenic, abundant in excretion/secretion products of the parasite, and do not cross-react with homologous host proteins. Ts26GST and TsTrx-1 showed sensitivity of 79 and 88%, specificity of 86 and 97%, PPV of 83 and 97% and NPV of 82 and 91%, respectively, for neurocysticercosis diagnosis. The recombinant antigens allowed the diagnosis of 70% (Ts26GST) and 80% (TsTrx-1) of patients having only one cysticercus. Further studies on specific regions of these proteins could improve T. solium diagnostics.

Investigation of Canine Distemper Virus Infection in Dogs in the Antalya Province

Canine distemper virus is one of the most prevalent infectious agents causing severe clinical symptoms among canids. Communal life-habitat for example clinics, dog-shelters, or rural areas is critical in terms of the transmission dynamics of CDV. In this study, blood samples from 92 dogs, aged 2 to 12 months, that were brought to the Rehabilitation Center and private veterinary clinics in Antalya with various internal medical problems were examined for Canine Distemper Virus (CDV) infection. Samples were tested using commercial immunochromatographic rapid test for detection of CDV-antigens and Enzyme Linked Immunosorbent Assay (ELISA) for detection of CDV-specific IgG and IgM antibodies. 
 The most common clinical findings in the 92 dogs sampled were mucopurulent discharge in the eye (45.65%), nasal hyperkeratosis (35.87%), nasal mucopurulent discharge (25%), cough (13.04%), diarrhea (8.70%), and fatigue (6.52%). It was observed that clinical findings were more intense in the early reconvalescent period. 5.43% (5/92) of the samples examined by immunochromatographic rapid test were positive. The positivity rates of IgG and IgM antibodies by ELISA were 19.56% (18/92) and 94.56% (87/92), respectively. Of the 92 dogs tested by ELISA for detection of IgG and IgM antibodies, 91 (98.91%) were positive for one or both IgG or IgM antibodies, and 1 (1.09%) was negative for both antibodies. 
 In conclusion, it was determined that CDV infection is actively circulating in the Antalya province and poses a risk for unvaccinated dogs in the region.

Establishment of a Blocking ELISA Detection Method for Against African Swine Fever Virus p30 Antibody.

African swine fever (ASF) is a highly lethal hemorrhagic viral disease of domestic pigs caused by African swine fever virus (ASFV). A sensitive and reliable serological diagnostic assay is required, so laboratories can effectively and quickly detect ASFV infection. The p30 protein is abundantly expressed early in cells and has excellent antigenicity. Therefore, this study aimed to produce and characterize p30 monoclonal antibodies with an ultimate goal of developing a monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) for ASFV antibody detection. Three monoclonal antibodies against p30 protein that were expressed in E. coli were generated, and their characterizations were investigated. Furthermore, a blocking ELISA based on a monoclonal antibody was developed. To evaluate the performance of the assay, 186 sera samples (88 negative and 98 positive samples) were analyzed and a receiver-operating characteristic (ROC) analysis was applied to determine the cutoff value. Based on the ROC analysis, the area under the curve (AUC) was 0.997 (95% confidence interval: 99.2 to 100%). Besides, a diagnostic sensitivity of 97.96% (95% confidence interval: 92.82 to 99.75%) and a specificity of 98.96% (95% confidence interval: 93.83 to 99.97%) were achieved when the cutoff value was set to 38.38%. Moreover, the coefficients of inter- and intra-batches were <10%, indicating the good repeatability of the method. The maximum dilution of positive standard serum detected by this ELISA method was 1:512. The blocking ELISA was able to detect seroconversion in two out of five pigs at 10 Dpi and the p30 response increasing trend through the time course of the study (0–20 Dpi). In conclusion, the p30 mAb-based blocking ELISA developed in this study demonstrated a high repeatability with maximized diagnostic sensitivity and specificity. The assay could be a useful tool for field surveillance and epidemiological studies in swine herd.

Comparison of fixed cell-based assay to radioimmunoprecipitation assay for acetylcholine receptor antibody detection in myasthenia gravis

ObjectiveTo compare specificity and sensitivity of a commercially available fixed cell-based assay (F-CBA) to radioimmunoprecipitation assay (RIPA) for acetylcholine receptor antibody (anti-AChR) detection in myasthenia gravis (MG). MethodsIn this retrospective diagnostic cohort study we reviewed the clinical information of suspected MG patients evaluated at the London Health Sciences Centre MG clinic who had anti-AChR RIPA and then F-CBA performed, in order to classify them as MG or non-MG. Classification of each patient as anti-AChR F-CBA-negative/positive, RIPA-negative/positive, and MG/non-MG permitted specificity and sensitivity calculations for each assay. ResultsSix-hundred-eighteen patients were included in study analysis. The median patient age at time of sample collection was 45.8 years (range: 7.5–87.5 years) and 312/618 (50.5%) were female. Of 618 patients, 395 (63.9%) were classified as MG. Specificity of both F-CBA and RIPA was excellent (99.6% vs. 100%, P > 0.99). One F-CBA-positive patient was classified as non-MG, although in retrospect ocular MG with functional overlay was challenging to exclude. Sensitivity of F-CBA was significantly higher than RIPA (76.7% vs. 72.7%, P = 0.002). Overall, 20/97 (21%) otherwise seronegative MG (SNMG) patients after RIPA evaluation had anti-AChR detected by F-CBA. ConclusionsIn our study anti-AChR F-CBA and RIPA both had excellent specificity, while F-CBA had 4% higher sensitivity for MG and detected anti-AChR in 21% of SNMG patients. Our findings indicate that F-CBA is a viable alternative to RIPA for anti-AChR detection. Prospective studies comparing F-CBA, RIPA and L-CBA are needed to determine optimal anti-AChR testing algorithms in MG.

Accuracy of multitarget indirect enzyme-linked immunoassay assay for detection of tuberculosis antibody.

BackgroundDiagnosis of tuberculosis (TB) is still difficult. The development of rapid and sensitive laboratory tools for the diagnosis of tuberculosis is a priority. This study aimed to develop an indirect enzyme-linked immunoassay (ELISA) assay for detection of TB antibody and explore its diagnostic value in patients with pulmonary tuberculosis (PTB) via a multi-center clinical evaluation.MethodsThe specific antigen, fusion antigen, and specific antibody peptide were obtained using molecular cloning and phage peptide library screening. An indirect ELISA assay was developed using multiple target materials. Further, the assay was validated in six institutions with clinically confirmed TB patients, non-TB patients with pulmonary disease, and healthy controls as research subjects.ResultsAn indirect ELISA assay was developed with 16 kD antigen, 11,488 (CFP10-MPT48-TB8.4) fusion antigen, and TB18 and pl2 as target antigens against TB antibody. The results of this multicenter study showed that the sensitivity, specificity, and the area under the receiver operating characteristic curve (AUC) of the assay were 48.25% [95% confidence interval (CI): 45.5–51.1%], 92.20% (95% CI: 90.7–93.5%) and 0.724 (95% CI: 0.707–0.741), respectively, and the cut-off value was 0.119. According to the meta-analysis, the combined ROC was 0.736 (95% CI: 0.692–0.779), I2=83.73%. The sensitivity of the sputum-positive PTB group (culture or smear positive) was 58.75% (95% CI: 52.96–65.00%); the sensitivity in sputum-negative group (culture or smear negative) was 37.38% (95% CI: 32.71–42.52%), respectively; the sensitivity of the sputum-positive group was significantly higher than that of sputum-negative group (OR =1.57, 95% CI: 1.29–1.92, P<0.001).ConclusionsMultitarget indirect ELISA assay based on specific-TB antigen, fusion antigen, and antibody peptide is of value for the diagnosis of PTB and can be used as an auxiliary rapid diagnostic tool to improve the sensitivity of sputum-negative TB.

A novel multiplex electrochemiluminescent immunoassay for detection and quantification of anti-SARS-CoV-2 IgG and anti-seasonal endemic human coronavirus IgG.

BackgroundMultiplex immunoassays capture a comprehensive profile of the humoral response against SARS-CoV-2 and human endemic coronaviruses. We validated a multiplex panel (V-PLEX Panel 2) from Meso Scale Diagnostics targeting antibodies against nine coronavirus antigens. Performance was compared against alternative single- and multi-antigen immunoassays.MethodsSera collected for clinical or public health testing from 2018 to 2020 (n = 135) were used to compare all tested platforms, and inter-test agreement was assessed by Cohen's kappa coefficient. Sample category (positive/negative) was assigned based on collection date relative to the index case in Canada, and SARS-CoV-2 PCR and serology results. 117 out of the 135 samples (31 positive, 86 negative) were assigned a category and were used to calculate sensitivity and specificity, with MSD's test results based upon manufacturer-set cut-offs.ResultsWe observed SARS-CoV-2 target sensitivities of 100% and specificities >94% for all antigens (RBD, Nucleocapsid, Spike) in V-PLEX Panel 2. When targets were combined, we found a SARS-CoV-2 sensitivity of 100% and specificity of 98.8% with no difference in performance compared to clinical assays, and Cohen's kappa ranging from 0.798 to 0.945 compared to surface plasmon resonance imaging (SPRi). Quantitative measurements of antibodies against the Spike protein of endemic human coronaviruses were concordant with SPRi.ConclusionMeso Scale Diagnostics’ V-PLEX Coronavirus Panel 2 allows for highly sensitive and specific detection of anti-coronavirus IgG, and is concordant with other serological assays for detection of antibodies against SARS-CoV-2 and the endemic human coronaviruses, making it a good tool for humoral response characterization after both infection and vaccination.

A bridging assay for detection and characterization of anti-drug antibodies to dostarlimab, a new anti-PD-1 therapeutic monoclonal antibody

Dostarlimab (JEMPERLI) is a humanized anti-programmed death 1 (PD-1) immunoglobulin (Ig)G4-kappa monoclonal antibody that binds to the PD-1 receptor and competitively inhibits binding of its ligands, PD-L1 and PD-L2. Dostarlimab was recently approved in the USA and the European Union. Because dostarlimab is a macromolecular therapeutic, it has the potential to elicit the formation of anti-drug antibodies, which have the capability to impact the drug’s safety and efficacy and to alter pharmacokinetics. The immunogenic potential of dostarlimab remains unknown, and it was therefore necessary to develop analytical assays to detect and characterize anti-drug antibodies as a key component in the mitigation of immunogenicity risk. Here, we present the development and optimization of a 3-tiered electrochemiluminescense bridging assay for the investigation of dostarlimab clinical immunogenicity. In this work, the full details of the method, statistical data analysis and cut point determinations, assay performance during clinical sample analysis, and associated regulatory expectations are discussed. The full validation of this 3-tier anti-drug antibody assay enabled dostarlimab immunogenicity evaluation in clinical studies. Trial registration: Clinicaltrials.gov, NCT02715284. Registered 9 March 2016

Preparation of different fragments of SARS-CoV-2 N protein and its application in fluorescence chromatography

Different fragments of SARS-CoV-2 nucleocapsid (N) protein were expressed and purified, and a fluorescence immunochromatography method for detection of SARS-CoV-2 total antibody was established. The effect of different protein fragments on the performance of the method was evaluated. The N protein sequence was analyzed by bioinformatics technology, expressed in prokaryotic cell and purified by metal ion affinity chromatography column. Different N protein fragments were prepared for comparison. EDC reaction was used to label fluorescence microsphere on the synthesized antigen to construct sandwich fluorescence chromatography antibody detection assay, and the performance was systemically evaluated. Among the 4 prepared N protein fragments, the full-length N protein (N419) was selected as the optimized coating antigen, N412 with 0.5 mol/L NaCl was used as the optimal combination; deleting 91-120 amino acids from the N-terminal of N412 reduced non-specific signal by 87.5%. the linear range of detection was 0.312-80 U/L, the limit of detection was 0.165 U/L, and the accuracy was more than 95%. A fluorescence immunochromatographic detection method for analysis of SARS-CoV-2 total antibody was established by pairing N protein fragments. The detection result achieved 98% concordance with the commercially available Guangzhou Wanfu test strip, which is expected to be used as a supplementary approach for detection of SARS-CoV-2. The assay could also provide experimental reference for improving the performance of COVID-19 antibody detection reagents.

DETEKSI PARASIT DARAH PADA KUCING LIAR (STRAY CATS) DENGAN METODE PEWARNAAN MDT DI PASAR TRADISIONAL SURABAYA

The aim of this study was to detect blood parasites of stray cats with an MDT staining test. Total samples were 40 blood taken from 4 markets in Surabaya, every market took 10 samples of stray cats. Three (3) cc Blood took from vena cephalica antebrachial anterior or vena saphena. Then blood samples were stained using MDT and checked under microscope 1000 magnification. The result showed 7 positive (17,5%) Anaplasma sp from 40 samples. This study needs advanced diagnosis using PCR, antibody detection (IFA test), ELISA, and western immunoblot assay although blood staining was detected by the agent.

Heparin-Induced Thrombocytopenia Testing: ELISA Based Anti-Platelet Factor 4 Polyspecific and IgG-Specific Antibody Detection Assays Compared to the Unfractionated Heparin Serotonin Release Assay

Introduction: Antibodies that cause heparin-induced thrombocytopenia (HIT) can be detected with either antigenic or functional assays. Previously, it has been shown that antigenic (ELISA based) assays that detect anti-platelet factor 4 (anti-PF4) IgG, IgM, or IgA (polyspecific) antibodies are more sensitive but less specific than functional assays such as the unfractionated serotonin release assay (UFH SRA), and that the use of anti-PF4 assays that detect IgG antibodies only, would increase the specificity but decrease the sensitivity of these assays for the detection of HIT antibodies that are prothrombotic (associated with positive functional assay). To date large epidemiologic studies have not confirm these findings. To evaluate the relative performance of anti-PF4 polyspecific and IgG-specific antibodies in their ability to detect prothrombotic HIT antibodies, we evaluated results of non-reflexive HIT panels that contained either anti-PF4 polyspecific or IgG-specific assays and unfractionated heparin serotonin release assays over an eight-year period at a U.S. reference laboratory.Methods: Test results for 2 HIT detection panels were compared: 1 panel had UFH SRA plus the polyspecific PF4 ENHANCED® assay (GTI Diagnostics, Waukesha, WI) and 1 panel had UFH SRA plus the IgG-specific Zymutest HIA IgG assay (Hyphen Biomed, France). Test results were from the last 4 years of use for each panel (2009 to 2012 for the polyspecific panel; 2017 to 2020 for the IgG-specific panel). UFH SRA was performed as described by Sheridan et al, (1986) with positivity defined as ≥20% serotonin release by low dose UFH and >50% suppression of release at high dose (100 U/mL) UFH. For each year and assay, test results were stratified by optical density (OD) results, and the percent of results positive by UFH SRA was determined for each OD range. Median yearly UFH SRA positivity rates for each OD interval were compared for anti-PF4 polyspecific vs IgG-specific antibody assays using non-parametric statistical testing, Mann-Whitney U test, two-tailed, with significance defined as <0.05.Results: HIT panels with either ELISA based assays detecting either anti-PF4 polyspecific or IgG specific antibodies demonstrated increasing UFH SRA positivity rates as OD increased. Approximately 50% UFH SRA positivity occurred when OD was in the 2.000 to range. No significant differences in SRA positivity were seen at any positive OD interval when comparing anti-PF4 polyspecific vs IgG-specific assays. A small but significant difference was seen when OD results were considered This observation may have been due to a in the review process (2017-2020): when a UFH SRA result was positive with a negative OD result, repeat UFH SRA testing was performed.Conclusions: Our study demonstrates that the correlations of UFH SRA positivity and OD measurements are similar for anti-PF4 IgG-specific and polyspecific antibody assays. These results suggest the assay types may perform similarly for the detection of HIT and importantly provide important predictive information as to when an optical density value will lead to a positive UFH SRA result. [Display omitted] DisclosuresWong: Quest Diagnostics: Current Employment, Current equity holder in publicly-traded company, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Worfolk: Quest Diagnostics: Current Employment. Bi: Quest Diagnostics: Current Employment. Noh: Quest Diagnostics: Current Employment. Espinoza: Quest Diagnostics: Current Employment. Wu: Quest Diagnostics: Current Employment. Sahud: Quest Diagnostics: Current Employment. Racke: Quest Diagnostics: Current Employment. Dlott: Quest Diagnostics: Current Employment.

Clinical Evaluation of Siemens SARS-CoV-2 Total Antibody assay and IgG assay using the Dimension EXL 200 in the Tokyo Metropolitan area

BackgroundWe evaluated the efficacy of the Siemens SARS-CoV-2 Total Antibody assay (CV2T) and IgG assay (CV2G) that can detect antibodies against the receptor binding domain of S antigen in patients with COVID-19 in a Tokyo metropolitan area. MethodsSensitivity and antibody levels were examined by CV2T and CV2G on Dimension EXL 200 using 236 serum samples obtained from 79 RT-PCR confirmed COVID-19 patients at multiple time points and were compared with disease severity by the World Health Organization criteria. The assay specificity was evaluated using samples collected before the COVID-19 pandemic. ResultsThe sensitivity of CV2T and CV2G were low (16.7–21.4%) in days 0–6 and increased to 43.8–52.5% in days 7–13 and to 80.8–90.0% in days 14–20. The seroprevalences persisted after day 21 to days past 42 regardless of disease severity. In every day grouping, mean antibody levels were higher in severe cases than in mild cases with a significant difference in days 14–20 and days 20–27. The specificity was 97.9 % (95% CI; 92.8–99.8) for CV2T and 99.0 % (95% CI; 94.6–100) for CV2G. ConclusionsOur results indicate a high specificity and high sensitivity at 14 days of CV2T and CV2G as antibody detection assays.

Specificity of SARS-CoV-2 Antibody Detection Assays against S and N Proteins among Pre-COVID-19 Sera from Patients with Protozoan and Helminth Parasitic Infections.

ABSTRACTWe aimed to assess the specificity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody detection assays among people with tissue-borne parasitic infections. We tested three SARS-CoV-2 antibody-detection assays (cPass SARS-CoV-2 neutralization antibody detection kit [cPass], Abbott SARS-CoV-2 IgG assay [Abbott Architect], and Standard Q COVID-19 IgM/IgG combo rapid diagnostic test [SD RDT IgM/SD RDT IgG]) among 559 pre-COVID-19 seropositive sera for several parasitic infections. The specificity of assays was 95 to 98% overall. However, lower specificity was observed among sera from patients with protozoan infections of the reticuloendothelial system, such as human African trypanosomiasis (Abbott Architect; 88% [95% CI, 75 to 95]) and visceral leishmaniasis (SD RDT IgG; 80% [95% CI, 30 to 99]), and from patients with recent malaria in areas of Senegal where malaria is holoendemic (ranging from 91% for Abbott Architect and SD RDT IgM to 98 to 99% for cPass and SD RDT IgG). For specimens from patients with evidence of past or present helminth infection overall, test specificity estimates were all ≥96%. Sera collected from patients clinically suspected of parasitic infections that tested negative for these infections yielded a specificity of 98 to 100%. The majority (>85%) of false-positive results were positive by only one assay. The specificity of SARS-CoV-2 serological assays among sera from patients with tissue-borne parasitic infections was below the threshold required for decisions about individual patient care. Specificity is markedly increased by the use of confirmatory testing with a second assay. Finally, the SD RDT IgG proved similarly specific to laboratory-based assays and provides an option in low-resource settings when detection of anti-SARS-CoV-2 IgG is indicated.

Comparative Evaluation of Four Potent Neospora caninum Diagnostic Antigens Using Immunochromatographic Assay for Detection of Specific Antibody in Cattle.

Neospora caninum is an intracellular protozoan parasite responsible for numerous abortion outbreaks and neonatal abnormalities in cattle. Rapid and accurate diagnosis is critical for N. caninum control owing to the lack of vaccine or drug-based control strategies. Herein, we evaluated the performance of four frequently used antigens in the diagnosis of N. caninum infection using immunochromatographic tests (ICTs) as a rapid, affordable, and field applicable tool. These antigens included recombinant proteins of N. caninum surface antigen 1 (NcSAG1), dense granule proteins 7 (NcGRA7) and 6 (NcGRA6), in addition to native Neospora lysate antigen (NLA). Our study revealed the utility of all antigen-based ICTs for detection of specific antibodies to N. caninum. However, the NcSAG1-based ICT was the best for detection of all control N. caninum-infected mouse or cattle sera, while NcGRA7 and NcGRA6-based ICTs exhibited specific ability to detect samples from acute and sub-acute infection in mice and cattle, respectively. Analyses of the NcSAG1-based ICT against enzyme-linked immunosorbent assays (ELISAs) of the same antigen revealed its efficiency in detection of field cattle samples as observed in high sensitivity (84.2%), specificity (93.5%), agreement (90%), and kappa value (0.78). The current knowledge provides an efficient platform for N. caninum control through on-site diagnosis of infected cattle.

Kidney Transplantation in Sensitized Patients

Dreaded complication of kidney transplantation in a sensitized patient is hyper-acute rejection immediately after vascular anastomosis. Although pretransplant complement-dependent cytotoxic cross match (CDC) has been the gold standard for many years, this assay is not perfect. The Luminex-based anti-HLA antibody detection assay is more sensitive and specific. While performing live-related kidney transplantation, luminex cross match is routinely performed but in a situation like deceased donor transplantation, in view of time constraints, we do CDC cross match and go ahead with transplantation if the result is negative (Cell lysis &lt;10%). Here, we present two cases of deceased donor transplantation where CDC cross match was negative, based on this report, we went ahead with kidney transplantation but report of Luminex cross match turned out to be positive after the transplantation was already over. Both the recipients had the features of hyper acute rejection. One patient could be salvaged but the other lost the graft.