A Rapid and Facile Purification Method for Glycan-Binding Proteins and Glycoproteins

Glycosylated proteins, namely glycoproteins and proteoglycans (collectively called glycoconjugates), are indispensable in a variety of biological processes. The functions of many glycoconjugates are regulated by their interactions with another group of proteins known as lectins. In order to understand the biological functions of lectins and their glycosylated binding partners, one must obtain these proteins in pure form. The conventional protein purification methods often require long times, elaborate infrastructure, costly reagents, and large sample volumes. To minimize some of these problems, we recently developed and validated a new method termed capture and release (CaRe). This method is time-saving, precise, inexpensive, and it needs a relatively small sample volume. In this approach, targets (lectins and glycoproteins) are captured in solution by multivalent ligands called target capturing agents (TCAs). The captured targets are then released and separated from their TCAs to obtain purified targets. Application of the CaRe method could play an important role in discovering new lectins and glycoconjugates. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Preparation of crude extracts containing the target proteins from soybean flour Alternate Protocol 1: Preparation of crude extracts from Jack bean meal Alternate Protocol 2: Preparation of crude extracts from the corms of Colocasia esculenta, Xanthosoma sagittifolium, and from the bulbs of Allium sativum Alternate Protocol 3: Preparation of Escherichia coli cell lysates containing human galectin-3 Alternate Protocol 4: Preparation of crude extracts from chicken egg whites (source of ovalbumin) Basic Protocol 2: Preparation of 2% (v/v) red blood cell suspension Basic Protocol 3: Detection of lectin activity of the crude extracts Basic Protocol 4: Identification of multivalent inhibitors as target capturing agents by hemagglutination inhibition assays Basic Protocol 5: Testing the capturing abilities of target capturing agents by precipitation/turbidity assays Basic Protocol 6: Capturing of targets (lectins and glycoproteins) in the crude extracts by target capturing agents and separation of the target-TCA complex from other components of the crude extracts Basic Protocol 7: Releasing the captured targets (lectins and glycoproteins) by dissolving the complex Basic Protocol 8: Separation of the targets (lectins and glycoproteins) from their respective target capturing agents Basic Protocol 9: Verification of the purity of the isolated targets (lectins or glycoproteins).

International collaborative study to establish reference preparations to standardise haemagglutination testing for anti-A and anti-B in normal intravenous immunoglobulins by the direct method

A joint project (coded BSP089) was run by the European Directorate for the Quality of Medicines & HealthCare (EDQM) of the Council of Europe, the National Institute for Biological Standards and Control (NIBSC) on behalf of the World Health Organization (WHO) and the Center for Biologics Evaluation and Research (CBER) of the U.S. Food and Drug Administration (FDA) to evaluate, in an international collaborative study, 3 lyophilised intravenous immunoglobulin (IVIG) preparations for their suitability to serve as Reference Preparations to standardise and control the highly variable haemagglutination testing for anti-A and anti-B in IVIG products. 23 laboratories tested candidate IVIG reference preparations consisting of a Positive control, a Negative control and a specifically formulated Limit test reference preparation to define the maximum (e.g., pharmacopoeial) limits of anti-A and anti-B haemagglutinins in IVIG products, where limits are applicable. Laboratories performed direct haemagglutination using papain-treated erythrocytes and/or indirect anti-globulin tests. For both methods, there was up to 16-fold variation in anti-A and anti-B titres, although there was good agreement over a 2-fold titre range for anti-A and anti-B between laboratories using the direct method for both the Positive control and Limit reference preparations. Comparative titration data for the Positive control and Limit reference preparations indicated that the use of a 'Limit' test reference preparation would facilitate identification of higher titre batches when the direct haemagglutination method is used. The Positive control, Negative control and Limit test preparations were adopted in November 2008 by the Commission of the European Pharmacopoeia (Ph. Eur.) as Biological Reference Preparations. The same preparations have been established as reference reagents by the WHO and the U.S FDA, including the maximal specifications defined by the Limit test preparation. This will facilitate global standardisation of haemagglutination tests for anti-A and anti-B, ensure that such tests are sufficiently sensitive and specific, and facilitate identification of batches that exceed maximum recommended levels of anti-A and anti-B antibodies.

[Comparison of commercial IFA, IHA and in-house IFA tests in the diagnosis of cystic echinococosis]

Hydatidosis is an endemic illness in many regions of world. Several serodiagnostic techniques have been evaluated for the diagnosis of cystic hydatid disease caused by Echinococcus granulosus. The aim of this study was to assess the efficiency of the commercial fluorescent antibody test (IFAT), indirect hemaglutination test (IHAT) and in-house IFA tests. For this purpose sera from one hundred patients who had been given a diagnosis of hydatid cyst by surgery were used. In-house IFA was developed using the germinal membrane of Echinococcus granulosus and sera were studied by the three different methods. As a result, the specificity of commercial IFA, IHA and in-house IFA was found to be 100% and sensitivities of these tests were 87.7%, 74.6% and 83.3% respectively. In conclusion, in-house IFA test is a useful and cost effective but difficult test to prepare for the routine laboratory.

International collaborative study to establish immunoglobulin (anti-D test) BRP batch 1

An international collaborative study was organised to establish a European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) and United States (US) Food and Drug Administration (FDA) reference preparation for the test for anti-D (anti-Rho) antibodies in human normal immunoglobulin for intravenous administration (IGIV). A candidate positive control (IGIV+anti-D) and negative control IGIV were compared to corresponding World Health Organization (WHO) International Reference Reagents using a direct haemagglutination reference method. Sixteen (16) laboratories participated in the collaborative study. Further to completion of the study, the materials assayed in the study were granted the status of Ph. Eur. and US FDA reference preparations for controlling the levels of anti-D in IGIV.

Comparison of the performance of microtube column systems and solid-phase systems and the tube low-ionic-strength solution additive indirect antiglobulin test in the detection of red cell alloantibodies

To compare the performance of seven currently available test systems in the detection of erythrocyte alloantibodies (ab), we tested in parallel 446 sera samples containing red cell ab [368 sera samples with ab that are assumed to be clinically significant (cs-ab) and 78 sera samples with ab that are assumed to be of minor clinical significance (ms-ab)] using the tube spin low-ionic-strength solution (addition method) indirect antiglobulin test (tube LISS-IAT), three microtube column agglutination techniques (DiaMed-ID, Ortho BioVue and Bio-Rad Scangel), one affinity adherence test system (CLB/Mast CellBind Screen) and two solid-phase tests [Biotest Solidscreen II and Immucor Capture-R Ready-Screen (4)]. To address the specificity of the three test systems under routine conditions, results of 4566 patient samples obtained using the tube LISS-IAT, results of 5205 patient samples obtained using the Scangel and results of 3560 samples obtained using the Capture-R were evaluated. The DiaMed-ID detected 344 cs-ab and 43 ms-ab, BioVue 333 cs-ab and 48 ms-ab, Scangel 348 cs-ab and 62 ms-ab, CellBind Screen 346 cs-ab and 47 ms-ab, Solidscreen 330 cs-ab and 38 ms-ab, Capture-R 358 cs-ab and 45 ms-ab and LISS-IAT 159 cs-ab and 12 ms-ab. In routine practice, erythrocyte cs-ab could be identified in 61 (67.8%) of 90 reactive sera (specificity: 98.6%) in the tube LISS-IAT, in 169 (58.7%) of 288 (94.4%) in Bio-Rad Scangel and in 101 (51.0%) of 198 reactive sera (94.3%) in Capture-R. We conclude that the sensitivity of the microcolumn, affinity adherence and solid-phase test systems in the detection of cs-ab was similar and was markedly superior to that of the conventional tube LISS-IAT. All high-sensitive test systems produced higher rates of false positives and ms-ab compared to the tube test. An individual cost-benefit analysis, considering the recent knowledge about the clinical significance of weak-reactive cs-ab, should be performed in every institution to decide whether and if so which high-sensitive screening system should be applied.

An International Standard for specifying the minimum potency of anti-D blood-grouping reagents: evaluation of a candidate preparation in an international collaborative study

BACKGROUND AND OBJECTIVES

The aim of this study was to evaluate a lyophilized monoclonal immunoglobulin M (IgM) anti-D preparation for use as an International Standard to specify a recommended minimum acceptable potency of anti-D blood-grouping reagents.

MATERIALS AND METHODS

The candidate International Standard (99/836) for specifying the minimum potency of anti-D blood-grouping reagents was evaluated against a wide range of commercial anti-D blood-grouping reagents in an international collaborative study involving 20 laboratories in 13 countries. Laboratories titrated reconstituted 99/836, in parallel with as many commercial anti-D blood-grouping reagents as were available to them, in tube tests according to specified haemagglutination methodology for low-protein (e.g. monoclonal IgM) and high-protein (e.g. polyclonal) reagents. The ratios of the mean end-point titres of the reagents to that of 99/836 within each laboratory were calculated.

RESULTS

The ratios of the mean titres of the low-protein reagents to the mean titre of 99/836 within a laboratory fell between 0.25 and 2 for 43 of the 45 low-protein anti-D reagents tested (i.e. the potencies of the low-protein reagents compared with 99/836 were between a 1:4 dilution of 99/836 to twice as potent as 99/836). The ratios of the mean titres of the high-protein reagents to the mean titre of 99/836 within a laboratory fell within 0.125 and 1 for eight out of the 10 high protein reagents tested.

CONCLUSIONS

By international consensus, a 1:3 dilution of reconstituted 99/836 was deemed appropriate to define a recommended minimum acceptable potency of low-protein anti-D blood-grouping reagents. A 1:8 dilution of reconstituted 99/836 was deemed appropriate to define a recommended minimum acceptable potency of high-protein anti-D blood-grouping reagents. On the basis of the results presented here, 99/836 was established by the World Health Organization as the 1st International Standard for specifying the minimum potency of anti-D blood-grouping reagents, in tube tests.

External quality assessment scheme in red blood cell serology: a 5-year experience in Thailand

From 2000 to 2004, 36, 58, 72, 78, and 86 laboratories participated in an external quality assessment scheme (EQAS) organized by the Department of Transfusion Medicine, Faculty of Medicine Siriraj Hospital. Each year the staff was requested to perform ABO grouping, D typing, antibody screening, antibody identification, and DATs on eight blood samples. Each participant received information on the correct test results and a coded summary. Regarding ABO grouping, the error rate ranged from 0.3 to 1.3 percent, mostly due to human errors. Error rates in D typing ranged from 0.7 to 5.7 percent, the most problematic being weak D phenotype interpretation. Although every sample was negative by the DAT, error rates due to false positive test results were determined to be 0.4 to 2.1 percent. Antibody screening errors were also found; however, errors steadily decreased from 4.2 percent in 2000 to 0.3 percent in 2004. Only 69.4 to 87.2 percent of laboratories performed antibody identification; however, correct results increased from 78.4 to 91.0 percent. In conclusion, an EQAS in RBC serology should be used to compare results from different laboratories and to identify those laboratories that need improvement in testing procedures.

International collaborative study to evaluate a candidate reference preparation to define an appropriate specified limit of anti-D in intravenous immunoglobulin products

BACKGROUND AND OBJECTIVES

The aim of the study was to evaluate a lyophilized intravenous immunoglobulin (IVIG) preparation containing anti-D (02/228; nominal reciprocal titre of 8) for its suitability to define the maximum limit of anti-D in IVIG products when used in a proposed reference method of direct haemagglutination of papain-treated erythrocytes, in an international collaborative study.

MATERIALS AND METHODS

Twenty laboratories tested 02/228 along with a negative control IVIG preparation and four IVIG samples containing different levels of anti-D. Nineteen laboratories performed direct haemagglutination methodology using papain-treated erythrocytes; five of these laboratories and one additional laboratory performed their in-house haemagglutination methodology (all indirect antiglobulin tests).

RESULTS

The mode titre of 02/228, obtained by using the proposed reference method, was 8 (62.5% of tests). However, there was wide variation in haemagglutination titres between laboratories for three of the four samples. Correcting the titres of the samples relative to those of the proposed reference preparation reduced the interlaboratory variability and increased the frequency of the mode titres in three out of four samples. The indirect antiglobulin tests also showed wide interlaboratory variability and were less sensitive than the direct method in four laboratories. Eleven of the 14 laboratories that expressed an opinion considered that the level of anti-D in 02/228 was appropriate to define a specified limit.

CONCLUSIONS

Our results demonstrate the necessity of using a reference preparation to define the maximum level of anti-D in IVIG products and ensure sufficient sensitivity in haemagglutination testing methodology. On the basis of these results, members of the European Pharmacopoeia Expert Group 6B recommended revision of the appropriate monograph to include this new specification and test. The Food and Drug Administration in the USA intends to adopt the same maximal specification defined by the reference preparation and to recommend the same test for the safety of IVIG products. Preparations 02/228 and 02/226 were also established by the World Health Organization as International Reference Reagents to standardize haemagglutination testing for anti-D in normal IVIG products.

D-dimer for the exclusion of acute venous thrombosis and pulmonary embolism: a systematic review

BACKGROUND

Despite extensive literature, the diagnostic role of d-dimer for deep venous thrombosis (DVT) or pulmonary embolism (PE) remains unclear, reflecting multiple d-dimer assays and concerns about differing sensitivities and variability.

PURPOSE

To systematically review trials that assessed sensitivity, specificity, likelihood ratios, and variability among d-dimer assays.

DATA SOURCES

Studies in all languages were identified by searching PubMed from 1983 to January 2003 and EMBASE from 1988 to January 2003.

STUDY SELECTION

The researchers selected prospective studies that compared d-dimer with a reference standard. Studies of high methodologic quality were included in the primary analyses; sensitivity analysis included additional weaker studies.

DATA EXTRACTION

Two authors collected data on study-level factors: d-dimer assay used, cutoff value, and whether patients had suspected DVT or PE.

DATA SYNTHESIS

For DVT, the enzyme-linked immunosorbent assay (ELISA) and quantitative rapid ELISA dominate the rank order for these values: sensitivity, 0.96 (95% confidence limit [CL], 0.91 to 1.00), and negative likelihood ratio, 0.12 (CL, 0.04 to 0.33); and sensitivity, 0.96 (CL, 0.90 to 1.00), and negative likelihood ratio, 0.09 (CL, 0.02 to 0.41), respectively. For PE, the ELISA and quantitative rapid ELISA also dominate the rank order for these values: sensitivity, 0.95 (CL, 0.85 to 1.00), and negative likelihood ratio, 0.13 (CL, 0.03 to 0.58); and sensitivity, 0.95 (CL, 0.83 to 1.00), and negative likelihood ratio, 0.13 (CL, 0.02 to 0.84), respectively. The ELISA and quantitative rapid ELISA have negative likelihood ratios that yield a high certainty for excluding DVT or PE. The positive likelihood values, which are in the general range of 1.5 to 2.5, do not greatly increase the certainty of diagnosis. Sensitivity analyses do not affect these findings.

LIMITATIONS

Although many studies evaluated multiple d-dimer assays, findings are based largely on indirect comparisons of test performance characteristics across studies.

CONCLUSION

The ELISAs in general dominate the comparative ranking among the d-dimer assays for sensitivity and negative likelihood ratio. For excluding PE or DVT, a negative result on quantitative rapid ELISA is as diagnostically useful as a normal lung scan or negative duplex ultrasonography finding.

Evaluation of 2-column agglutination versus conventional tube technique for antibody screening

The study aimed to determine the specificity and sensitivity of the Ortho BioVue two-column agglutination system for the detection of low concentrations of clinically significant antibodies in serum. The BioVue system was compared with the conventional tube technique (LISS-Coombs indirect antiglobulin test), and the two-stage Papenzyme test was used to resolve discrepancies between the two methods. We tested 3000 serum samples from randomly selected patients at King Hussein Medical Centre. Both the antibody screening and identification gave negative results in 2952 patients and positive results in 48 patients. We found the BioVue system to be the more sensitive technique. However, if papain enzyme-treated cells were included in the conventional tube technique when applied to antibody screening and identification, both methods would be of comparable sensitivity.

A preliminary comparison of flow cytometry and tube agglutination assays in detecting red blood cell-associated C3d

This study compared flow cytometric analysis with tube agglutination assays for the detection of red blood cell (RBC)-associated complement and immunoglobulins (Igs). RBCs from 20 patients with reactive tube direct antiglobulin tests (DATs) were evaluated by flow cytometry with anti-C3d, anti-IgG, anti-IgM and anti-IgA. Serial samples were also tested from a patient at risk of passenger lymphocyte haemolysis. Results of flow cytometry and tube assays for anti-IgG were as follows: 12 of 20 samples reactive in both; six of 20 nonreactive in both; two of 20 discordant with a reactive tube and a nonreactive flow cytometry assay. Anti-C3d results showed nine of 20 reactive in both and 11 of 20 discordant with a nonreactive tube and a reactive flow cytometry assay. In the IgM flow cytometry assay, three samples were reactive with anti-IgM. Samples from a group A woman who was transplanted with stem cells from a group B donor showed that on days 3 through 6 post-transplant, the flow cytometry assays for anti-IgG and/or anti-C3d were reactive, whilst the tube assays were nonreactive. In conclusion, flow cytometric analysis is more sensitive than the tube assay for the detection of RBC-associated C3d. Further studies are needed to determine the correlation of C3d levels with clinical sequelae.

Diagnosis of canine parvovirus by rapid immunomigration on a membrane

Rapid immunomigration on a membrane was applied to the diagnosis of canine parvovirus (CPV) in 128 samples of faeces containing four strains of parvovirus (two CPV-2a strains, including one vaccine strain, and two CPV-2b strains). The results were compared with the results of haemagglutination and ELISA sandwich techniques. The new test was quick and easy to use, and made it possible to identify both the CPV-2a and CPV-2b strains. Its detection thresholds per gram of faeces corresponded to specific haemagglutination titres of between 320 and 640 and a virus titre of between 10(4) and 10(5) CCID50 (dose required to infect 50 per cent of cell cultures).

Prevalence of human parvovirus B19 in blood donors as determined by a haemagglutination assay and verified by the polymerase chain reaction

BACKGROUND AND OBJECTIVES

Transmission of human parvovirus B19 (PV B19) by transfusion of blood and blood products is well documented. Although PV B19 infection is connected with severe complications in some recipients, donor screening is not yet mandatory. In this study the prevalence of PV B19, as detected by a haemagglutination assay (the Human PV B19 Antigen-Test), was assessed. In addition, the persistence of B19 DNA and the serological status of blood donors was also assessed. The specificity and utility of the Human PV B19 Antigen-Test for donor screening was investigated and compared with other screening strategies.

MATERIALS AND METHODS

The prevalence of PV B19 viraemia was assessed in 28 972 donations from 15,660 remunerated donors by means of the haemagglutination assay. Reactive results were confirmed by the polymerase chain reaction (PCR).

RESULTS

Overall, 255 donations gave reactive or indeterminate results in the screening assay. Four donations/donors detected by the haemagglutination assay were confirmed as positive for B19 DNA by PCR. Therefore, a frequency was detected of 1:7243 B19-positive donations and 1:3915 positive donors. Specificity was determined to be 99.1%. Follow-up showed the persistence of viraemia in low concentrations for prolonged time-periods.

CONCLUSION

Blood donations with a high level of human PV B19 viraemia can be detected by the haemagglutination assay, which is rapid and easy to perform. The presence of neutralizing antibody may inhibit specific haemagglutination.

[Quality of rapid tests for determination of infectious mononucleosis]

BACKGROUND

The Norwegian centre for quality assurance in primary health care, NOKLUS, was established in 1992 to ensure the quality of laboratory analyses performed in primary health care. This article evaluates results from the surveys of infectious mononucleosis.

MATERIAL AND METHODS

From 1996 to 2000, five serum panels were sent to participating practices in order to control test-kits designed for serological rapid diagnosis of infectious mononucleosis. 648 practices participated in this external quality assessment in 2000. Target values were determined using the Paul Bunell Davidsohn test. The results obtained for each type of test and variables that might have affected the results were evaluated.

RESULTS

Outdated kits or kits close to the date of expiration showed poorer results than the other test-kits. The quality of the results depended mainly on the type of test-kit used and the training level of the persons performing the analyses.

INTERPRETATION

The best performing tests in these surveys were Clearview IM (Unipath Limited) and Contrast Mono (Genzyme diagnostics). These two tests are among the three most frequently used tests, out of a total of thirteen, in our surveys.

Two methods for rapid serological diagnosis of acute leptospirosis

Leptospirosis is a common and underdiagnosed zoonosis. Two rapid assays for serological diagnosis of acute leptospirosis in diagnostic laboratories, the immunoglobulin M (IgM)-dipstick assay and the indirect hemagglutination assay (IHA), were evaluated and compared with standard assays. Sera were examined from 104 patients admitted to a hospital for investigation in a leptospirosis diagnostic protocol. Specimens for serology were taken on days 1 and 4 of the patients' hospital stay. Antibodies were detected using an IgM-enzyme-linked immunosorbent assay (ELISA), microscopic agglutination test (MAT), an IgM-dipstick assay, and an IHA. Fifty-one patients were found to have leptospirosis. The sensitivity of the IgM-dipstick assay was 98%, its specificity was 90.6%, its positive predictive value was 90.9%, and its negative predictive value was 98%. The sensitivity of the IHA was 92.2%, its specificity was 94.4%, its positive predictive value was 95.9%, and its negative predictive value was 92.7%. The standard IgM-ELISA and MAT, were positive in the first samples tested from 67 and 55% of the cases, respectively, and the rapid IgM-dipstick assay and IHA were positive in 71 and 49%, respectively, in the first sample tested. Both rapid assays are highly sensitive and specific. Neither requires specialized equipment, and both are suitable for use in diagnostic laboratories.

[Reliability of results evaluation for the passive hemagglutination test in pertussis obtained from WSSE laboratories]

This study was undertaken for assessing of the reliability of the passive haemagglutination test with B. pertussis endotoxin in 18 laboratories of the Sanitary Epidemiological Stations. Each laboratory determined the level of pertussis antibodies in three serum samples twice, at interval of two weeks. The correct results were obtained in 7 laboratories (38.9%). The results of pertussis antibodies determination in only one or two samples were differed more than twice from correct in 5 additional laboratories; in this way the test was carried out satisfactorily in 12 laboratories (66.7%). Reproducibility of the results was good in 12 laboratories (66.7%). The study showed the necessity of repeated interlaboratory controls and periodic training of laboratory workers for raising of the quality and reliability of serological investigations for pertussis.

Specific IgG avidity in acute and chronic human fascioliasis

The detection of IgG avidity in sera is potentially useful in the diagnosis of acute and chronic infection. We studied IgG avidity in 31 patients with fascioliasis, with the aim of evaluating the clinical application of this test to confirm the diagnosis of incubating cases and to distinguish between acute and chronic cases. Of the 31 cases, 13 were incubating and had a mean avidity index of 57.28 +/- 5.79%. The 18 chronic cases had an avidity index of 68.80 +/- 8.92%. The difference was highly significant. We conclude that IgG avidity is a reliable means of identifying the stage of fascioliasis and suggest a cut-off point of 59.90% to distinguish between acute and chronic infection.

Comparison of the performance of four microtube column agglutination systems in the detection of red cell alloantibodies

BACKGROUND

The purpose of this study was to compare the performance of four currently available microtube column agglutination systems in the detection of red cell alloantibodies to that of the standard tube low-ionic-strength solution (LISS) indirect antiglobulin test (IAT) (tube LISS-IAT).

STUDY DESIGN AND METHODS

In a comparative study, 172 sera, previously demonstrated to contain red cell alloantibodies, were tested in parallel by the tube LISS-IAT and three microtube column agglutination techniques (DiaMed-ID, Ortho BioVue, and Sanofi-Pasteur Scangel) and one affinity-adherence test system (Gamma ReACT). Tests were performed simultaneously by a single person on freshly thawed sera that had been frozen at -20 degrees C.

RESULTS

The rate of detection of clinically significant alloantibodies (n = 154) in microtube column systems was very similar. One hundred forty-one sera (91.6%) reacted in the DiaMed-ID, 139 (90.3%) in the ReACT, 139 (90.3%) in the BioVue, and 142 (92.2%) in the Scangel. Only 117 (76.0%) of these sera reacted in the tube LISS-IAT. The detection rates for 18 antibodies of minor clinical significance (anti-M, -N, -P1, -Le(a), and -Le(b)) varied among the test systems: DiaMed-ID, 5 (28%); ReACT, 7 (39%); BioVue, 14 (78%); Scangel, 10 (56%); and tube LISS-IAT, 6 (33%). Antibody reactivity as determined by titer and score was very similar in all microtube column systems and higher in these systems than in the tube LISS-IAT.

CONCLUSION

The sensitivity of all four microtube column systems in the detection of clinically significant red cell alloantibodies was similar and was markedly superior to that of the tube LISS-IAT. An individual cost-benefit analysis should be performed in every institution to decide whether a microtube column system should be applied. If so, the antibody screen in the microtube column agglutination system should ideally be performed in advance of the crossmatch to provide time to screen for compatible units.

Development of an antigen spot test for detection of coronavirus in bovine fecal samples

We have developed a rapid and sensitive microimmunodot blot assay, the antigen spot test (AST), for the detection of bovine coronavirus (BCV) antigen from neonatal calf fecal samples. The AST procedure can be completed in 3.5 h, whereas the previously reported immunodot blot assays require 10 to 12 h. Ninety-six samples can be tested per membrane, and 10 membranes (960 samples) may be processed by a single technologist in 1 working day. The effects of detergents, oxidizing chemicals, chaotropic agents, and enzyme substrates in improving the sensitivity and signal-to-noise ratio of the AST were studied. Finally, the sensitivity and specificity of AST for the detection of BCV antigen were compared to those of a sandwich enzyme-linked immunosorbant assay (ELISA) and a hemagglutination assay (HA). Of 347 field samples tested by all three methods, 94.2% were positive by AST, 91.4% were positive by ELISA, and 86.7% were positive by HA. The sensitivity of the AST was determined to be 100% compared to the results of the ELISA reference method. The specificity of the AST was 67%, which reflects a lower limit of detection of 10(4) viral particles per ml in a 10% fecal suspension.

Specificity of a novel red blood cell agglutination assay ('SimpliRED') for HIV-1/HIV-2 infection

The specificity and ease of use of a novel red blood cell assay for detection of HIV-1/HIV-2 antibodies was evaluated on 125 blood donor samples in Nairobi. The specificity was estimated as > 99%. The assay correctly identified five positive samples in the population, and was easy and rapid to perform. The data confirm results obtained for the assay from other regions and suggest that the assay is suitable for detection of HIV-infected individuals by minimally equipped laboratories.

Evaluation of purified antigens in haemagglutination test (IHA) for determination of cross reactivities in diagnosis of fascioliasis and schistosomiasis

Indirect haemagglutination test (IHA) commercially available kits (Fumouze) for diagnosis of fascioliasis and schistosomiasis were evaluated for cross reactivity. Sera of 85 selected schistosomiasis patients (Group I) were tested for schistosomiasis titers employing purified Schistosomiasis mansoni egg antigen. Sensitivity of the test was 75.3%. Positive sera (Group II: 64 sera) were retested using kits for fascioliasis employing purified adult Fasciola hepatica antigen to detect any cross reactions. Specificity was 96.9%. In addition, thirty eight (38) sera of selected fascioliasis cases (Group III) were retested using IHA kits for schistosomiasis. Specificity was 94.7%. It was found that IHA employing purified specific antigens both for schistosomiasis and fascioliasis gives good specificities and helps to avoid cross reactions between the two serious endemic trematode infections offering reliable diagnosis.

Unreliability of current screening tests for syphilis in chronic psychiatric patients

OBJECTIVE

This study examined whether psychiatrists perform adequate diagnostic screening for syphilis in patients with chronic mental illness.

METHOD

Two hundred patients with chronic mental illness underwent testing for syphilis with the commonly used RPR test and the microhemagglutination assay for Treponema pallidum (MHA-TP). Sensitivities of the two tests were compared.

RESULTS

A substantial number of patients with negative results on RPR tests had reactive MHA-TPs and would have not been identified as having had syphilis with the use of RPR testing alone.

CONCLUSIONS

Nontreponemal tests such as the RPR test are less likely than treponemal tests to detect syphilis appropriately in chronically mentally ill patients, and specific treponemal tests such as the MHA-TP should be considered.

Comparison of in vivo and in vitro methods for determining unitage of diphtheria antitoxin in adsorbed diphtheria-tetanus (DT) and diphtheria-tetanus-pertussis (DTP) vaccines

In view of the current efforts to find a reliable in vitro method which can suitably act as an alternative for determining the potency of the diphtheria component in a combined vaccine, we have analysed experimental batches by the method proposed by WHO [1] i.e. challenge method in guinea pigs. The same batches were also analysed by the alternative antibody induction method as suggested in the Indian Pharmacopoeia (I.P.) [2] which is similar to the old method suggested in the British Pharmacopoeia (B.P.) 1973. As per I.P. the initial part of raising the antibodies remains unaltered but the actual titration of diphtheria antitoxin from the immunised guinea pigs was performed by using the following in vitro methods: a) indirect haemagglutination test using human "O" red blood cells to coat diphtheria toxoid using chromic chloride as the coupling agent [3]; b) toxin neutralisation test using Vero cells [4]; c) a double diffusion technique in agar gel for titration of diphtheria antitoxin [5]. Our findings show clearly that the results of two in vivo methods i.e. Challenge Test, Alternative I.P. Method and the above-mentioned three in vitro methods are comparable and would certainly reduce the number of animals required by making a combination of in vivo and in vitro techniques to give us an assessment of the potency of the vaccine to be tested.

[Serological diagnosis of Chagas disease: self-sufficiency and interlaboratory concordance]

American trypanosomiasis (Chagas' disease) is becoming a relatively common condition in North America. Diagnosis at the chronic stage depends on demonstration of specific antibodies in body fluids, since parasitologic or pathologic diagnosis is uncertain at this stage. Therefore, standardization of immunodiagnostic techniques is mandatory, and it depends on antigen quality. Locally prepared antigens and crude extracts obtained from Mexican isolates, -both from infected vector and human cases-were compared using three different immunodiagnostic assays-indirect immunofluorescence, hemagglutination and enzyme linked immunosorbent assay (ELISA)-at two different laboratories from the Instituto Nacional de Cardiología and the Instituto Nacional de Diagnóstico y Referencia Epidemiológicos. Concordance between laboratories reached a significant Kappa value (0.8) and sensitivity, specificity and predictive values of individual diagnostic assays were adequate to use these tests in clinical diagnoses. This is the first attempt to standardize immunodiagnostic techniques in Mexico.

Factors affecting the sensitivity and reproducibility of passive haemagglutination test for the quantitation of measles-specific antibodies

Various factors affecting the passive haemagglutination test (PHA) for the quantitation of measles-specific antibodies have been evaluated with the aim to obtain maximum sensitivity and reproducibility of the test. The antigen used for sensitization was prepared in Vero cells using Edmonston 245 strain of measles virus. Sheep red blood cells (SRBCs) were found most sensitive for use in PHA test. The optimum dilution of tannic acid was found to be 1:40,000 for tanning of fixed and 1:10,000 for unfixed SRBCs, when the tanning was carried out at 4 degrees C overnight. Fixed and tanned SRBCs sensitized with 32 HA units of measles HA antigen at 56 degrees C for 30 mins were found optimal. SRBCs from different sheep affected the sensitivity of the assay. Stability study of SRBCs showed that storage at -70 degrees C of glutaraldehyde-fixed and sensitized SRBCs gave better results as compared to those stored at -20 degrees C and +4 degrees C. Tanned SRBCs could be stored at -70 degrees C only up to 15 days. Sensitized SRBCs with-stood two cycles of freezing and thawing after removal from -20 degrees C and -70 degrees C. Sensitized SRBCs could be stored for 120 days without any significant loss of titer at -20 degrees C, +4 degrees C or 22 degrees C; when lyophilized with stabilizers, there was a slight decline in the titer after exposure at 37 degrees C for 30 days. The lyophilized sensitized SRBCs after reconstitution were found to be stable at +4 degrees C for 3 days without any loss in the titer.(ABSTRACT TRUNCATED AT 250 WORDS)

Selection of European Union standard reference sera for use in the serological diagnosis of infectious bovine rhinotracheitis

A study, consisting of three trials, was undertaken in order to find standard reference sera for use in serological diagnostic procedures for infectious bovine rhinotracheitis (IBR) in the European Union (EU). A total of forty-nine laboratories participated in the trials, in which panels of positive, weak positive, and negative candidate sera were tested blind by neutralisation, indirect and blocking enzyme-linked immunosorbent assay, indirect immunofluorescence and passive haemagglutination. A serum which scored positive in all tests in all laboratories was selected as a strong positive standard serum. The chosen negative standard serum gave negative results in virtually all tests. A 1/36 dilution of a positive serum was chosen as the weak positive standard serum and only very sensitive techniques were able to score it positive. Three EU reference sera are now available for the standardisation of serological tests for IBR.

Determination of lectin-cell-binding parameters by a new agglutination technique

We applied a recently described technique which is based on a light transmission/scattering method to determine the association characteristics of the Geodia lectin to sheep erythrocytes. The agglutination assays were performed in a total volume of 3 ml with 5.4 x 10(6) erythrocytes/ml. At a concentration of 360 ng/ml 50% of the lectin molecules were bound to the cells within the first 10 s of incubation. Scatchard analyses revealed an association constant (K(a)) of 0.9 +/- 0.1 x 10(8) M-1 and a number of 3.8 +/- 0.6 x 10(6) lectin binding sites on one erythrocyte. The method was also successfully applied to determine quantitatively the inhibitory potential of sugars competing with cell surface glycoproteins for the lectin binding site. At a lectin concentration of 360 ng/ml 1 mM of lactose or 70 mM of D-N-acetylgalactosamine are required to inhibit lectin-mediated agglutination by 50%. These analyses confirm the potential of the novel light absorption agglutination technique to evaluate lectin characteristics.

[Method for studying anti-complement reagents: use of freeze-thawed sensitized erythrocytes]

The use of red blood cells coated with complement fractions using low ionic strength saline conditions is part of the evaluation of anti-complement antibodies, specially monoclonal antibodies used for antiglobulin reagents. This work shows that such cells stored in liquid nitrogen allow satisfactory long-term studies except for the anti-C3g antibodies.

Enzyme-linked immunosorbent assay for leptospirosis immunoglobulin M specific antibody using surface antigen from a pathogenic Leptospira: a comparison with indirect hemagglutination and microagglutination tests

A search for a sensitive and specific test for human leptospirosis was made by enzyme-linked immunosorbent assay for immunoglobulin M specific antibody (IgM ELISA) using a surface antigen from L.interrogans serovar bataviae, L. interrogans serovar pyrogenes and L.interogans serovar icterohaemorrhagiae. The IgM ELISA tests using each of the three antigens were evaluated in 103 sera primarily positive by microagglutination test (MA). Optical density of these IgM ELISA tests showed good correlation. The IgM ELISA using antigen from serovar bataviae was compared with MA and indirect hemagglutination (IHA) in 20 sera primarily positive by IHA, and 103 sera primarily positive by MA. IgM ELISA and IHA using antigen prepared from serovar bataviae in 103 sera positive for MA had a sensitivity of 98.06 and 92.23 per cent respectively. In 20 sera primarily positive by IHA, IgM ELISA and MA showed sensitivity of 80 and 45 per cent respectively. The surface antigen used in IgM ELISA is broadly specific making IgM ELISA a sensitive and specific test for human leptospirosis. IHA agreed more with IgM ELISA in comparison to MA. As MA is not sensitive for early infection, IHA and IgM ELISA should be in routine use in general laboratories.

Syphilis--an STD on the increase

The number of reported cases of syphilis, including primary, secondary and congenital syphilis, has been rapidly rising since 1987. The greatest increases have occurred in urban areas. An association between human immunodeficiency virus infection and syphilis has been established. Primary syphilis is manifested by a clean, painless ulcer called a chancre. Secondary disease often presents with constitutional symptoms and a maculopapular rash. Most infants with congenital syphilis are born without signs of infection. Serologic testing for both nontreponemal and treponemal antibodies is essential for diagnosis. Penicillin is the treatment of choice for all stages of syphilis. Case reporting and treatment of sexual contacts are two aspects of this disease that warrant greater attention from physicians.

[Erroneous information in the epidemiological surveillance of hepatitis B]

False positive results obtained in the determination of the immune markers of hepatitis A by the methods of the passive reverse hemagglutination test and the enzyme immunoassay distort the course of the registration of the epidemic process and deteriorate the quality of the antiepidemic measures ensured to the population. The necessity of the standardization of available test systems is postulated.

Rapid presumptive identification of human black pigmented Bacteroides species

A simple and reliable technique is described for the rapid presumptive identification of black pigmented Bacteroides species of human origin. This method involved a microtitration technique that detected the hydrolysis of specific chromogenic enzyme substrates and haemagglutination of sheep erythrocytes. Pure cultures of black pigmented Bacteroides strains, representing the eight human species, were successfully differentiated and identified within 4 h by the identification scheme developed with this method. This is a highly reproducible method and the scheme should be useful in laboratories lacking the sophisticated equipment often needed for the identification of black pigmented Bacteroides.

A comparison of passive haemagglutination test and immunofluorescent test for antibody to native deoxyribonucleic acid

Antibody to double-stranded DNA is a specific marker for systemic lupus erythematosus. The recommended method for detection of this antibody is immunofluorescence. Haemagglutination was developed and the results of antibody detection were evaluated with those obtained by immunofluorescence. Human group O erythrocytes were treated with glutaraldehyde and coated with DNA from calf thymus. Testing in 169 active and inactive SLE sera, 59 sera were positive and 91 sera were negative by both methods. Five sera were negative by haemagglutination but positive by immunofluorescence. Fourteen sera with low haemagglutination titer were negative by immunofluorescence. The correlation between the results obtained by both methods were highly significance with contingency coefficient of 0.61 and correlation coefficient between the results of 78 sera positive by both or either method was 0.74 (p less than 0.001). Sixty-three sera from blood donors and seventy sera from pregnant women were negative by the two techniques. PHA is simpler, quicker and can be assayed in laboratories without the use of fluorescent microscope. It can be established as a very useful alternative test to immunofluorescence.

Pattern of reactive serological tests for syphilis in different population groups attending the University College Hospital Ibadan (1976-1985)

A review of the reactive serological tests for syphilis was carried out. An overall seroreactivity of 5.1% was obtained over the 10-year period reviewed. A subtle but steady rise in the incidence of syphilitic infections was noted, from 7 to 10 new cases per 1000 population between 1970 and 1975. The predictive characteristics obtained from the screening tests show that the tests are reliable diagnostic tests when the results are carefully interpreted, and the medical personnel can be alerted of the prevalence of syphilitic infections.

Primary standardization for the ELISA of serum thyroperoxidase and thyroglobulin antibodies and their prevalence in a normal Welsh population

This paper describes the use of ELISA techniques, together with university available primary standards, for the assay of the thyroid autoantibodies anti-thyroperoxidase (TPOAb) and anti-thyroglobulin (TgAb). The data obtained using ELISA compared well with that obtained by passive haemagglutination giving correlation coefficients of 0.79 and 0.83 respectively. TPOAb and TgAb concentrations were assayed in serum samples from 832 healthy individuals aged between 18 and 45 years and cut-off values for both antibodies have been defined (TPOAb less than 19.6kIU/l; TgAb less than 98kIU/l). Applying these cut-off values, some 10% of the population showed elevated anti-thyroid antibody activity and, when divided by sex, a majority of this group belonged to the female population.

Improved ELISA for thyroid microsomal auto-antibodies. Comparison with haemagglutination and immunofluorescent techniques

Thyroid microsomal antibodies (TMA) and thyroglobulin antibodies (TGA) are strongly associated with auto-immune thyroid disease. TMA and TGA have been mostly detected by means of either immunofluorescence (IF), tanned red cell haemagglutination (TRCH), or radio-immunoassay (RIA) until the recent development of the enzyme-linked immunosorbent assay (ELISA). The ELISA has not been as extensively used in TMA detection as in the assay for TGA. The RIA method, though more sensitive, is technically and materially very demanding while the TRCH and IF are simpler to perform but are less sensitive. The main problem with the ELISA for the detection of TMA appears to be the interference of TGA present in some test sera reacting with thyroglobulin present as a contaminant in the thyroid microsomal preparation. In this study, we compared the TMA results from an ELISA system designed to eliminate TGA interference with those of IF and TRCH. The ELISA system in which TGA interference was eliminated without concurrent inhibition of the test reaction that gives rise to false negatives was more sensitive than either IF or TRCH. A significant number of samples was falsely reported as negative by both TRCH and IF. The correlation of the degree of positivity between TRCH and ELISA was moderate and was higher than that between ELISA and IF, though both were highly significant. The ELISA technique for TMA detection described here is a more efficient, more sensitive and also more cost-effective system than either TRCH or IF, both of which should now be replaced by ELISA, provided steps are taken to avoid false positives and false negatives.

[Standardization of the direct hemagglutination reaction induced by bacteria of the genus Lactobacillus]

L. bulgaricus, L. casei var. rhamnosus, and L. plantarum cells grown in agar-containing (but not liquid) thioglycol medium for 3 days have been shown to be capable of inducing mannose-resistant agglutination of human and guinea-pig erythrocytes, while giving a considerably weaker reaction with erythrocytes from animals of other species (ox, sheep, dog, rabbit, rat and mouse). The optimum conditions for the test are presented.

Partial characterization of the hemagglutinin of Alcaligenes faecalis

The hemagglutinin of Alcaligenes faecalis was partially characterized. Hemagglutination (HA) was blocked by enzymes inactivating proteins, by heat, and by antisera but not by sugar-blocking substances. Pili were not determined to be a factor in HA activity. There was no connection between virulence and HA activity.

Evaluation of assays for the detection of antibodies to rubella. A report based on data from the College of American Pathologists Surveys of 1982

Data from laboratories participating in the College of American Pathologists Surveys in 1982 provided information on the trends in testing for antibodies to rubella. Methods used by participants included: passive hemagglutination, 29%; latex agglutination card assay test, 25%; hemagglutination inhibition, 19%; enzyme immunosorbent assays, 13%; indirect fluorescent antibody assays, 11%; and radioimmunoassay, 3%. The results from these methods generally agreed well with the standard HI test, particularly for detection of immunity in negative and strongly positive samples. Laboratories should use caution, however, that the tests they use give satisfactory results with low titered sera. Compared to laboratories using the one to three-day-old chick cells with Heparin-MnCl2 for HI, laboratories using Human O Cells tended to get higher titers, and laboratories using Fixed Chick cell or Kaolin methods tended to get lower titers.