Adapting to the Coronavirus Pandemic: Building and Incorporating a Diagnostic Pipeline in a Shared Resource Laboratory

In March 2020, with lockdown due to the coronavirus pandemic underway, the Francis Crick Institute (the Crick) regeared its research laboratories into clinical testing facilities. Two pipelines were established, one for polymerase chain reaction and the other for Serology. This article discusses the Cricks Flow Cytometry Science Technology Platform (Flow STP) role in setting up the Serology pipeline. Pipeline here referring to the overarching processes in place to facilitate the receipt of human sera through to a SARs‐CoV‐2 enzyme‐linked immunosorbent assay result. We examine the challenges that had to be overcome by a research laboratory to incorporate clinical diagnostics and the processes by which this was achieved. It describes the governance required to run the service, the design of the standard operating procedures (SOPs) and pipeline, the setting up of the assay, the validation required to show the robustness of the pipeline and reporting the results of the assay. Finally, as the lockdown started to ease in June 2020, it examines how this new service affects the daily running of the Flow STP. © 2020 The Authors. Cytometry Part A published by Wiley Periodicals LLC on behalf of International Society for Advancement of Cytometry.

Results of the National External Quality Assessment for Toxoplasmosis Serological Testing in China

Background

Toxoplasmosis is typically diagnosed by serologic testing. External quality assessment (EQA) of clinical laboratories could ensure the accuracy and reliability of serological tests. We assessed the quality of toxoplasma serological assays in Chinese clinical laboratories by an EQA performed between 2004 and 2013 by the National Center for Clinical Laboratories.

Methodology and Findings

EQA panels were prepared and shipped at room temperature to participating laboratories that employed toxoplasma IgG and IgM serological detection. By 2013, 5,384 EQA test reports for toxoplasma-specific IgM and 2,666 reports for toxoplasma-specific IgG were collected. Enzyme-linked immunosorbent (ELISA) and chemical immunofluorescent assays were the most commonly used detection methods. The overall coincidence rates of negative samples were better than those of positive samples. The overall EQA score for toxoplasma-specific IgM detection ranged between 84.3% and 99.6%. The ratio of laboratories that achieved correct IgG detection ranged from 61.1% to 99.3%. However, the inter- and intra-assay variabilities were found to be considerable. The most common problem was failure to detect low titers of antibody.

Conclusion

The EQA scheme showed an improvement in toxoplasma serological testing in China. However, further optimization of assay sensitivity to detect challenging samples remains a future challenge.

ELISA as a possible alternative to the neutralization test for evaluating the immune response to poliovirus vaccines

This review describes several enzyme-linked immunosorbent assay (ELISA) techniques proposed to replace the neutralization test for detecting neutralization-relevant antibodies to polioviruses in recipients of inactivated poliovirus vaccine and oral poliovirus vaccine, and for seroepidemiologic studies. Comparisons of results from ELISA and the neutralization test suggest that ELISA variants, based on the principle of blocking or binding inhibition that emulate the neutralization test, might offer an alternative to the neutralization test. However, to replace the neutralization test with ELISA would first require extensive studies with very large numbers of serum samples, including sera having low titers of neutralizing antibodies, in order to obtain reliable and statistically sound validation.

Impact of solid phase antibody testing on organ allocation in the United States

The implementation of the solid phase antibody assays has allowed for the detection and characterization of human leukocyte antigen (HLA) specific antibodies with greater sensitivity and specificity. This information can then be used along with the donor's HLA typing to predict crossmatch results (a virtual crossmatch). Using these data and the level of immunological risk assessed to the antibodies detected, the determination of unacceptable antigens can be made. The calculated panel reactive antibody (CPRA) provides for a means to determine the frequency of these unacceptable antigens in the donor population and thereby predict the probability of a positive crossmatch. In 2009, the Organ Procurement Transplant Network administered by the United Network for Organ Sharing adopted the CPRA as the means to define sensitization and to assign allocation points. Follow-up studies have shown that the number of organ offers refused due to a positive crossmatch has decreased significantly and has saved money through the elimination of unnecessary testing. An additional benefit has been the increased number of sensitized patients being transplanted successfully. Through technical improvements and the refined interpretation of the solid phase antibody assays, continual progress is being made in the definition of the unacceptable antigens and the ability to transplant sensitized patients.

[GM1-dot-EIA for the detection of toxin-producing Vibrio cholerae strains]

A new variant of enzyme immunoassay (EIA) has been developed on the basis of GM1 gangliosides to detect the toxin-producing Vibrio cholerae strains--GM1-dot-EIA. Experiments were run using a nitrocellulose membrane to bind GM1 gangliosides and polyclonal antitoxic serum to detect cholerogen. GM1-dot-EIA testing identified cholera toxin in 11 of 13 supernatants of V. cholerae eltor ctx(+) strains isolated from man and in 3 of 7 supernatants of V. cholerae eltor ctx(+) strains isolated from water. These data agree with those obtained in CM1-EIA. There was no reaction with the supernatants of other microorganisms. The sensitivity of the technique was 10 ng/ml. Thus, the simple and specific GM1-dot-EIA may be recommended to detect toxin-producing V cholerae strains isolated from man and water.

Rocky mountain spotted fever in the United States, 2000-2007: interpreting contemporary increases in incidence

Rocky Mountain spotted fever (RMSF), a potentially fatal tick-borne infection caused by Rickettsia rickettsii, is considered a notifiable condition in the United States. During 2000 to 2007, the annual reported incidence of RMSF increased from 1.7 to 7 cases per million persons from 2000 to 2007, the highest rate ever recorded. American Indians had a significantly higher incidence than other race groups. Children 5-9 years of age appeared at highest risk for fatal outcome. Enzyme-linked immunosorbent assays became more widely available beginning in 2004 and were used to diagnose 38% of cases during 2005-2007. The proportion of cases classified as confirmed RMSF decreased from 15% in 2000 to 4% in 2007. Concomitantly, case fatality decreased from 2.2% to 0.3%. The decreasing proportion of confirmed cases and cases with fatal outcome suggests that changes in diagnostic and surveillance practices may be influencing the observed increase in reported incidence rates.

[Recent advances in the immunodiagnosis of human cystic echinococcosis]

Human cystic echinococcosis is a severe zoonotic infection caused by the larval stage of the taeniid tapeworm Echinococcus granulosus. The infection may be fatal if proper treatment is not provided; hence, early diagnosis is very important. Currently, ELISA and immunoblotting are the most reliable tests for serodiagnostic purposes, although their accuracy is largely dependent on the quality of the antigenic source used. Hydatid cyst fluid has been the antigenic extract of choice for primary immunodiagnosis of the disease, which is mainly based on the detection of antigens B and 5. Several problems are associated with this extract, however, including a lack of sensitivity and specificity, and difficulties with standardization of its use. This paper reviews recent advances in the identification and characterization of novel antigens that may be useful for the immunodiagnosing of human cystic echinococcosis, with emphasis on progress in recombinant technologies and synthetic peptides. Novel approaches are discussed, such as the design of antigenic extracts from other developmental stages of the parasite, as well as the usefulness of serum cytokine detection in the clinical follow-up of affected patients after surgical or pharmacological treatment.

Diagnosing tuberculosis infection in the 21st century: new tools to tackle an old enemy

The century-old tuberculin skin test (TST) was until recently the only means of diagnosing latent tuberculosis infection (LTBI). Recent advances in mycobacterial genomics and human cellular immunology have resulted in two new blood tests that detect tuberculosis infection by measuring in vitro T-cell interferon (IFN)-gamma release in response to two unique antigens that are highly specific for Mycobacterium tuberculosis but absent from bacille Calmette-Guérin (BCG) vaccine and most nontuberculous mycobacteria. One assay, the enzyme-linked immunospot (ELISpot) [T-SPOT.TB; Oxford Immunotec; Oxford, UK] enumerates IFN-gamma-secreting T cells, while the other assay measures IFN-gamma concentration in supernatant by enzyme-linked immunosorbent assay (ELISA) [QuantiFERON-TB Gold; Cellestis; Carnegie, Australia]. A large and growing clinical evidence base indicates that both tests are more specific than the skin test because they are not confounded by prior BCG vaccination. In active tuberculosis, ELISA has similar sensitivity to the skin test, while ELISpot is significantly more sensitive. Current cross-sectional evidence suggests that for diagnosis of LTBI, sensitivity of ELISA is similar to TST, while ELISpot appears more sensitive. High specificity will enable clinicians to avoid unnecessary preventive treatment in BCG-vaccinated persons without infection who commonly have false-positive TST results. High sensitivity could enable accurate targeting of preventive treatment to patients with infection at the highest risk of progression to active tuberculosis who frequently have false-negative TST results due to impaired cellular immunity. However, longitudinal studies are needed to define the predictive value of positive blood test results for progression to tuberculosis.

International multicenter evaluation of autoantibodies to ribosomal P proteins

Autoantibodies to the ribosomal phosphoproteins (Rib-P) are a serological feature of patients with systemic lupus erythematosus (SLE). The reported prevalence of anti-Rib-P antibodies in SLE ranges from 10 to 40%, being higher in Asian patients. The variation in the observed frequency may be related to a number of factors but is dependent in large part on the test system used to detect the autoantibodies. An association of anti-Rib-P with central nervous system involvement and neuropsychiatric manifestations of SLE has been controversial. In the present international multicenter study, we evaluated the clinical accuracy of a new sensitive Rib-P-specific enzyme-linked immunosorbent assay based on recombinant Rib-P polypeptides. The results showed that 21.3% of 947 SLE patients, but only 0.7% of 1,113 control patients, had a positive test result (P < 0.0001). The sensitivity, specificity, positive and negative predictive values, and diagnostic efficiency were determined to be 21.3%, 99.3%, 95.6%, 62.2%, and 65.3%, respectively. When evaluated in the context of participating centers, the prevalence of anti-Rib-P antibodies was found in descending frequency, as follows: China (35%) > Poland (34%) > Japan (28%) > United States (26%) > Germany (Freiburg; 23.3%) > Denmark (20.5%) > Germany (Berlin; 19%) > Mexico (15.7%) > Israel (11.7%) > Brazil (10%) > Canada (8%). The substantial data from this study indicate that the prevalence of anti-Rib-P antibodies may not be restricted to the genetic background of the patients or to the detection system but may depend on regional practice differences and patient selection. We confirm previously reported associations of antiribosomal antibodies with clinical symptoms and serological findings. Remarkably, we found a lower occurrence of serositis in Rib-P-positive lupus patients.

Hematocrit Influences Immunoassay Performance for the Measurement of Tacrolimus in Whole Blood

The comparison between the MEIA II and the EMIT assays for tacrolimus measurement and the interference by the hematocrit were evaluated in 93 samples from routine therapeutic monitoring at tacrolimus concentrations less than 9 microg/L (group A). Additionally, the incidence of false-positive results were determined in samples (n=46) from patients who were not receiving the drug (group B). In group A, no statistical differences were observed between the mean+/-SD values obtained by MEIA II (5.14+/-2.28 microg/L) and EMIT (4.61+/-1.79 microg/L). The correlation coefficient and the regression equation (95% CI) between both assays, were 0.761 and EMIT=1.088 (0.90, 1.35) MEIA II -0.38 (-1.65, -0.46), respectively. When the samples were stratified according to the hematocrit, the median differences between the methods (MEIA II minus EMIT) were as follows: hematocrit<or=25%, 0.45 microg/L; hematocrit 25%-35%, 0.30 microg/L; and hematocrit>35%, 0.25 microg/L (P=0.02). In group B, false-positive results (above the detection limit) were observed in 63.04% of samples analyzed by MEIA II and in 2.17% of samples analyzed by EMIT. The median differences in apparent tacrolimus results were significantly higher in the samples with the lowest hematocrit: 2.2 microg/L, 1.4 microg/L, and 0.0 microg/L in samples with hematocrit<or=25%, 25%-35%, and >35%, respectively. In conclusion, the differences in the tacrolimus results obtained by MEIA and EMIT assays were higher in samples from patients with hematocrit less than 25%, and the MEIA assay demonstrated a high incidence of false-positive results.

A comparability study of the emerging protein array platforms with established ELISA procedures

Recent developments in microarray technology have made it possible to perform immunoassays in a multiplexed format. This ability is highly desirable given the potential for greater throughput analysis. In spite of the obvious advantages, a number of issues arise as a result of multiplexing the reactions. In this study, we have assessed the performance characteristics that are associated with the transfer of technology from a uniplexed to a multiplexed format. Two solution phase array platforms were chosen for this study: the commercially available Luminex(100) xMap system (Austin, Texas, USA) and the UltraPlex technology devised by SmartBead Technologies Ltd. (Cambridge, UK). For this comparative study, a test for the presence of six autoantibodies in a selection of human patient serum samples was chosen as a model system. The multiplexed Luminex xMap and SmartBead UltraPlex assays were generally comparable. However, both systems generated some results that were at variance with those obtained by ELISA. The different methods used for the assignment of the cut-off levels for each of the assays within any given platform was identified as the major source of these non-concordant results. The present study demonstrates that array platforms have the potential to be used in immunodiagnostics providing that suitable cut-off levels are established.

Diagnostic value of anti-GM1 ganglioside serology and validation of the INCAT-ELISA

The Inflammatory Neuropathy and Treatment (INCAT) group developed a standardized ELISA method for the detection of serum anti-GM1 antibodies. The diagnostic value of anti-GM1 antibodies determined by this method has not yet been established in large groups of patients. We assessed the reproducibility, sources of variation, optimal cut-off values and evaluated the diagnostic relevance of the INCAT-ELISA in various groups of patients and controls (N=1232). The coefficient of variance was 11.2% for IgM and 3.8% for IgG. High IgG titers were only found in Guillain-Barré syndrome (GBS) and other inflammatory polyneuropathies. High IgM titers were associated with GBS and multifocal motor neuropathy. Low IgM titers had no additional diagnostic value. The INCAT-ELISA is a reliable test with additional diagnostic value in specific clinical situations.

New Enzyme-Linked Immunosorbent Digoxin Assay on the ADVIA?? IMS??? 800i System Is Virtually Free from Interference of Endogenous Digoxin-like Immunoreactive Factors

Endogenous digoxin-like immunoreactive factors (DLIF) may crossreact with antidigoxin antibody and falsely elevate immunoassay results. Recently, a new enzyme-linked immunosorbent chemiluminescent assay for digoxin has been available for use on the ADVIA IMS (Integrated Modular System) 800i analyzer (Bayer Diagnostics). We studied potential interference of DLIF with this new digoxin assay. We analyzed 30 serum specimens from patients who have pathologic conditions that may increase serum DLIF concentrations. These patients were never exposed to digoxin or other agents that may lead to a measurable digoxin concentration. We also analyzed 10 specimens from neonates, 10 cord blood specimens, and 10 amniotic fluid specimens. Apparent digoxin concentrations were measured using the new enzyme-linked immunosorbent digoxin assay (IMS-Digoxin), a fluorescence polarization immunoassay (FPIA), and also a chemiluminescent immunoassay (CLIA, run on ACS:180(R) system from Bayer Diagnostics). We observed measurable apparent digoxin levels with the FPIA in 4 uremic patients (range 0.21-0.36 ng/mL, digoxin equivalent), 7 patients with liver disease (range 0.21-0.72 ng/mL), and 3 patients in the third trimester of pregnancy (0.22-0.66 ng/mL). We also observed measurable DLIF concentrations with the FPIA in 2 neonates (0.22 and 0.36 ng/mL), 5 cord blood specimens (range 0.21-1.18 ng/mL), and 5 amniotic fluid specimens (0.21-0.50 ng/mL). None of these DLIF-positive specimens showed any measurable digoxin concentration using the IMS-Digoxin or the CLIA assay. When serum specimens containing elevated concentrations of DLIF but no digoxin (as measured by FPIA) were supplemented with known concentrations of digoxin, we observed falsely elevated digoxin concentrations, as expected, only by the FPIA. In contrast, we observed a good agreement between the target and observed concentrations when the new IMS-Digoxin or the CLIA assay was used. We conclude that the IMS-Digoxin assay is free from interference of DLIF.

Tracking genes from seed to supermarket: techniques and trends

Analytical techniques to track plant genes in the environment and the food chain are essential for environmental risk assessment, government regulation and production and trade of genetically modified (GM) crops. Here, I review laboratory techniques to track plant genes during pre-commercialization research on gene flow and post-commercialization detection, identification and quantification of GM crops from seed to supermarket. At present, DNA- and protein-based assays support both activities but the demand for fast, inexpensive, sensitive methods is increasing. Part of the demand has been generated by stringent food labeling and traceability regulations for GM crops. The increase in GM crops, changes in GM crop design, evolution of government regulations and adoption of risk-assessment frameworks will continue to drive development of analytical techniques.

Evaluation of the most current and effective methods in the analysis of chlorinated dioxins in ground beef

Chlorinated dioxins are the group of environmental pollutants consisting of 210 chlorinated dibenzo-p-dioxins and dibenzofurans. They are highly toxic and persistent. They are lipophilic and can easily biomagnify in the food chain, hence posing a serious threat to human health. The daily consumption of low-level contaminated food, mainly of animal origin, leads to the accumulation of dioxins in the human body. The exposures of the general human population to dioxins and the specific issues of a risk assessment of dioxin pose serious concerns in public environmental and nutritional health. This paper reviews the analysis of chlorinated dioxins in ground beef. The sources of contamination of chlorinated dioxins in ground beef are first reviewed to form a basis for a clear understanding of the health implications of chlorinated dioxins in the human food chain and why it is necessary to monitor the level of dioxins in animal food products, especially ground beef. The methods of collection, sampling, and processing of ground beef, and the methods of sample clean up prior to the analysis, are reviewed. Emphasis is laid on the new techniques that are available and that might be effective in the analysis of chlorinated dioxins in ground beef. Among these new methods and techniques are: the synergistic combination of ELISA/GC/MS, direct sample introduction to /GC/MS-MS, automated clean-up method, and the supercritical fluid extraction methods. The possible treatments of results from each method and technique are discussed and their respective efficiencies are compared. Finally, quality control and quality assurance parameters are evaluated for levels of accuracy, reproducibility, and precision.

Immunological assay for assessing the efficacy of glatiramer acetate (Copaxone) in multiple sclerosis. A pilot study

Recently we described an enzyme-linked immunoadsorbent spot (ELISPOT) assay allowing us to define an immunological response profile observed in multiple sclerosis patients treated with Copaxone (glatiramer acetate; GA) but not untreated subjects [4]. The profile encompasses three criteria, a) reduced proliferative response to GA (as observed with a standard primary proliferation assay); b) strong in vitro activation of interferon-gamma-producing T cells at high concentrations of GA (as detected by interferon-gamma ELISPOT); and c) activation of interleukin-4-producing T cells over a wider range of concentrations of GA (as detected by interleukin-4 ELISPOT). It is at present unknown whether the immunological response to GA correlates with the clinical response. To address this question we performed the pilot study reported here. We asked the major German multiple sclerosis centres to send us blood samples from all GA-treated patients who were going to discontinue treatment because of treatment failure. The clinical nonresponders either had an unchanged or increased exacerbation rate, or developed a secondary progressive course during GA treatment. Over more than one year, we prospectively collected 9 samples from clinical non-responders. We compared the immune response to GA of peripheral blood mononuclear cells from the 9 clinical nonresponders with 15 clinical responders, using a standard proliferation assay combined with ELISPOT assays for detection of interferon-gamma and interleukin-4 secreting cells. Thirteen (86 %) of the 15 clinical responders met at least 2 of the immunological response criteria mentioned above. In contrast, only 2 (22 %) of the 9 clinical nonresponders met two of the immunological criteria (p = 0.0006). We conclude that the ELISPOT assay may provide a promising additional tool for monitoring the treatment response in multiple sclerosis patients treated with GA.

Evolution of the enzyme-linked immunosorbent spot assay for post-transplant alloreactivity as a potentially useful immune monitoring tool

Post-transplant monitoring of cellular immunity has the potential to guide alterations in medical therapy. To this end, our laboratory has developed an enzyme-linked immunosorbent spot (ELISPOT) assay for detection of peripheral blood alloimmunity. Peripheral blood lymphocytes (PBLs) from normal volunteers and from renal allograft recipients were tested against donor stimulator cells for their ability to respond in 'one-way' cytokine ELISPOT assays. T cell depletion of donor spleen or PBLs eliminated donor cell cytokine secretion while preserving the ability of these cells to present allo-antigen to responding T cells. Alloreactive IFN-gamma-producing PBLs derive from the memory T cell pool and are readily detectable in recipients of renal allografts taking immunosuppressant medications. A significant expansion of IFN-gamma-producing donor-reactive memory PBLs was detectable at 4-6 months post-transplant in those who had experienced an acute rejection episode compared with those with a stable post-transplant course. The data demonstrate the feasibility of repeated post-transplant monitoring of allograft recipients, and provide the foundation for improving the care of human transplant recipients through rational clinical decision-making based on measures of immune function.

Detection of genetically modified organisms in foods

Legislation enacted worldwide to regulate the presence of genetically modified organisms (GMOs) in crops, foods and ingredients, necessitated the development of reliable and sensitive methods for GMO detection. In this article, protein- and DNA-based methods employing western blots, enzyme-linked immunosorbant assay, lateral flow strips, Southern blots, qualitative-, quantitative-, real-time- and limiting dilution-PCR methods, are discussed. Where information on modified gene sequences is not available, new approaches, such as near-infrared spectrometry, might tackle the problem of detection of non-approved genetically modified (GM) foods. The efficiency of screening, identification and confirmation strategies should be examined with respect to false-positive rates, disappearance of marker genes, increased use of specific regulator sequences and the increasing number of GM foods.

Rapid monitoring of recombinant protein products: a comparison of current technologies

Specific measurement of recombinant protein titer in a complex environment during industrial bioprocessing has traditionally relied on labor-intensive and time-consuming immunoassays. In recent years, however, developments in analytical technology have resulted in improved methods for protein product monitoring during bioprocessing. The choice of product-monitoring technology for a particular bioprocess will depend on a variety of assay factors and instrument-specific factors. In this article, we have compiled an overview of the advantages and disadvantages of the most commonly used technologies used: electrochemiluminescence, optical biosensors, rapid chromatography and nephelometry. The advantages of each technology for measuring both small and large recombinant therapeutic proteins are compared with a conventional enzyme-linked immunosorbent assay (ELISA) technique.

Advances in the diagnosis of some parasitic diseases by monoclonal antibody-based enzyme-linked immunosorbent assays

Advances in diagnostic assays for parasitic diseases include the use of monoclonal antibodies (MAbs) in antigen capture and competitive inhibition enzyme-linked immunosorbent assays (C-ELISA). Antigen capture ELISAs for Anaplasma marginale and Cryptosporidium parvum provide direct detection of these parasites during clinical disease, and the C-ELISA format has been adapted for detection of anti-Babesia equi, anti-A. marginale and anti-bluetongue virus antibodies. False-positive results may occur when antigen preparations in other ELISA formats are contaminated with Escherichia coli, erythrocyte or cell-culture antigens. The C-ELISA format overcomes problems of antigen purity, since the specificity of the C-ELISA depends solely on the MAb used. For this reason, the C-ELISA format is highly suited for use with recombinant antigens. Also, the use of recombinant protein in diagnostic assays precludes the need to infect animals for antigen production when the antigen cannot be produced in cell culture.