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To examine the consistency and comparability of anti-hepatitis B core antigen (anti-HBcAg) assays, four blood donation centers of the Red Cross in the Federal Republic of Germany tested 4,080 unselected blood donors with six different tests in parallel. Confirmation testing of reactive samples was done in the National Reference Center for Viral Hepatitis. Depending on the test kit used, 4.1 to 9.9% of serum samples were initially positive and 2.9 to 7.5% were repeatedly positive. Sixteen percent of serum samples were positive in at least one test but only three percent were positive in all six tests. Statistical analysis of frequency distribution of optical densities for each test suggested that there should be a correction of the cutoff values. This reduced the number of false-positive results by half, but a significant proportion of discrepant results could not be resolved. The lack of specificity and consistency requires cautious interpretation of isolated anti-HBcAg results in clinical specimens. Screening of predominantly anti-HBcAg-negative populations (e.g., blood donors) by the current anti-HBcAg test kits will almost necessarily give unsatisfactory results.

Three specific immunological methods for the determination of netilmicin and two enzyme immunoassays for gentamicin were compared for assaying serum netilmicin. The commercial kits we used were Radioimmunoassay (RIA), Substrate Labelled Fluorescence Immunoassay (gentamicin) ( SLFIA ), Homogeneous Enzyme Immunoassay (gentamicin and netilmicin) (EMIT) and Fluorescence Polarization Immunoassay ( FPIA ). After analysing spiked calf serum samples in the range of 0-15.8 mg X 1(-1) netilmicin, extensive statistical analysis was performed. The Performance Index was used to qualify the different methods. Results show that the SLFIA (gentamicin) kit is a very acceptable method for the determination of serum netilmicin levels, well comparable with the EMIT (gentamicin) kit and the EMIT (netilmicin) kit. FPIA and RIA require expensive specialized apparatus so it is only economically feasible when other drugs or substances are also determined on the same apparatus. The abilities and specific needs of each laboratory will play an important role in the choice of a method, because the tested kits are all within the range we need from a clinical point of view.

IgM detection by enzyme-linked immunosorbent assay (ELISA) is the most used method of establishing a cytomegalovirus (CMV) infection during pregnancy. In this paper, we discuss the results obtained assaying 1,000 sera from pregnant women by two ELISA kits: a traditional indirect ELISA and a more recent IgM-capture ELISA. All the sera that gave a positive ELISA value with one or both kits were further tested by immunoblotting (IB) to establish which CMV polypeptides were detected by IgM antibodies. From the results obtained, IgM-capture ELISA seems less sensitive than indirect ELISA, but correlates better with serological evidence of active CMV infections as judged by typical IB profiles.

The immunodiagnosis of tropical parasitic diseases has begun to benefit significantly from recent developments such as: in vitro cultivation of pathogenic parasites; new immunochemical methods for producing and purifying immunodiagnostic reagents; emergence of reagent monoclonal antibodies; and the development of sensitive immunoassay methodology for detecting low concentrations of circulating or excreted pathogens or their markers in body fluids.

Enzyme immunoassays of eicosanoids have been developed in recent years. Although the assays are quite different in the enzyme label and the type of development, they represent a major conceptual change for the immunoanalysis of these compounds. We have coupled covalently acetylcholine esterase from electrophorus electricus to various eicosanoids, including PGE2, PGD2, PGF2α, 6-keto-PGF1α, TXB2, dinor-TXB2, ll-dehydro-TXB2, and LTC4. Using 96-well microtiter plates coated with the second antibody, we could obtain results equal to or better than those obtained with corresponding [125I]-radioiodinated tracers when available. The high sensitivity of this method combined to semiautomation may prove to be a useful tool to investigate the level of these substances from various biological fluids. In addition, this enzyme has been coupled successfully to other substances, suggesting that it could be used as a general label to produce nonisotopic tracers.

We followed the levels of circulating immune complexes (CIC) in 27 patients with Kawasaki disease (KD) from the acute stage of the disease through convalescence, using the test for platelet-reactive IgG-IC, and C1q-binding and conglutinin-binding enzyme immunoassays. CIC were detected by one or more techniques in all but one patient. Positive results were obtained most often with the test for platelet-reactive IgG-IC. Measurement of complement components C3 and C4 in 14 patients revealed an increase in C3 levels during the first few weeks of the disease and normal levels of C4. The blood platelet count correlated directly with the level of platelet-reactive IgG-IC. The highest levels of CIC were found during weeks 3 through 7 after the onset of disease. Measurement of CIC is, however, not applicable to the clinical follow-up of patients with KD.

During February and March 1984, 207 fecal samples from infants and children with gastroenteritis were tested for rotavirus with four techniques: two enzyme immunoassays (Rotazyme; Abbott Laboratories, North Chicago, Ill., and Enzygnost-Rotavirus; Calbiochem-Behring, La Jolla, Calif.) and two latex agglutination tests (Rotalex; Orion Research, Inc., Cambridge, Mass., and Slidex Rota-Kit; Biomérieux). All stool samples were also tested for yeasts and bacterial pathogens. Electron microscopy was used to investigate discrepant results. We found 47% positive samples with Enzygnost-Rotavirus, 38% with Rotazyme, 37% with Slidex Rota-Kit, and 34% with Rotalex. No specimen was found positive by Rotazyme only or Slidex Rota-Kit only. On the contrary, 12 samples which were positive with Enzygnost-Rotavirus only and 3 which were positive with Rotalex only were not confirmed as positive by electron microscopy. Both enzyme immunoassays gave 6% equivocal results; Slidex Rota-Kit gave significantly fewer equivocal results than did Rotalex: 2.9% versus 9.7% (P less than 0.01). The sensitivity and specificity of latex tests compared favorably with that of enzyme immunoassays. Latex agglutination tests can be performed by unskilled personnel and are rapid and relatively cheap. They appear to be very suitable for routine laboratory work and may prove useful for large-scale screening in developing countries.

Enzyme immunoassays (EIAs) are widely used to diagnose chlamydial infections in patients attending genitourinary medicine clinics. They are relatively easy to perform and are suitable for testing large numbers of samples. The objective of this study was to determine what proportion of women with chlamydial infection, defined as the presence ofChlamydia trachomatis in a cervical smear or deposit and/or in the urinary tract, detected by means of a sensitive direct fluorescent antibody test could also be identified by using two commercially available EIAs to test cervical samples. One hundred fifty-one women attending the genitourinary medicine clinic at St. Mary's Hospital, London, were enrolled. The use of the Chlamydiazyme (Abbott Diagnostics, UK) and MicroTrak (Syva, UK) EIAs resulted in the identification of only 56 % and 63 %, respectively, of women with chlamydial infection detected by direct fluorescent antibody staining. Thus, the EIAs available for detection of chlamydiae in cervical samples are inadequate for identifying all infected women. Improvement might be achieved by testing multiple samples or by resorting to tests of greater sensitivity.

There is uncertainty regarding how stable complement analytes are during long-term storage at – 80 °C. As part of our work program we have measured 17 complement biomarkers (C1q, C1 inhibitor, C3, C3a, iC3b, C4, C5, C9, FB, FD, FH, FI, TCC, Bb, sCR1, sCR2, Clusterin) and the benchmark inflammatory marker C-reactive protein (CRP) in a large set of plasma samples (n = 720) that had been collected, processed and subsequently stored at – 80 °C over a period of 6.6–10.6 years, prior to laboratory analysis. The biomarkers were measured using solid-phase enzyme immunoassays with a combination of multiplex assays using the MesoScale Discovery Platform and single-plex enzyme-linked immunosorbent assays (ELISAs). As part of a post hoc analysis of extrinsic factors (co-variables) affecting the analyses we investigated the impact of freezer storage time on the values obtained for each complement analyte. With the exception of five analytes (C4, C9, sCR2, clusterin and CRP), storage time was significantly correlated with measured plasma concentrations. For ten analytes: C3, FI, FB, FD, C5, sCR1, C3a, iC3b, Bb and TCC, storage time was positively correlated with concentration and for three analytes: FH, C1q, and C1 inhibitor, storage time was negatively correlated with concentration. The results suggest that information on storage time should be regarded as an important co-variable and taken into consideration when analysing data to look for associations of complement biomarker levels and disease or other outcomes.

Recently, elevated titers of antibody to HTLV I have been demonstrated in patients with tropical spastic paraparesis and multiple sclerosis. We evaluated the possible role of human retroviruses HTLV I and III in Canadian patients with multiple sclerosis and chronic idiopathic myelopathy. Using sensitive enzyme immunoassays, we were unable to find antibody to either HTLV I or III in 201 patients with multiple sclerosis, 29 patients with chronic myelopathy, 51 patients with other neurological disorders, or 29 normal subjects. These data do not support a role for these viruses in the cause of sporadic multiple sclerosis and chronic myelopathy in a regionally based Canadian population, but do not exclude a role for other antigenically distinct retroviruses.

Background Numbers of giraffes are declining rapidly in their native habitat. As giraffe research and conservation efforts increase, the demand for more complete measures of the impact of conservation interventions and the effects of captive environments on animal health and welfare have risen. We compared the ability of six different enzyme immunoassays to quantify changes in fecal glucocorticoid metabolites (FGM) resulting from three sources: adrenocorticotropic hormone stimulation test, transport, and time of day that samples were collected. Results Two male giraffes underwent ACTH injections; all six assays detected FGM increases following injection for Giraffe 1, while only three assays detected FGM increases following injection for Giraffe 2. Consistent with other ruminant species, the two 11-oxoetiocholanolone assays (one for 11,17-dioxoandrostanes and the other for 3α,11-oxo metabolites) measured the most pronounced and prolonged elevation of FGM, while an assay for 3β,11β-diol detected peaks of smaller magnitude and duration. Both of the 11-oxoetiocholanolone assays detected significant FGM increases after transport in Giraffes 3–7, and preliminary data suggest FGM detected by the assay for 11,17-dioxoandrostanes may differ across time of day. Conclusions We conclude the assay for 11,17-dioxoandrostanes is the most sensitive assay tested for FGM in giraffes and the assay for FGM with a 5β-3α-ol-11-one structure is also effective. 11-oxoetiocholanolone enzyme immunoassays have now been demonstrated to be successful in a wide variety of ruminant species, providing indirect evidence that 5β-reduction may be a common metabolic pathway for glucocorticoids in ruminants. As FGM peaks were detected in at least some giraffes using all assays tested, giraffes appear to excrete a wide variety of different FGM. The assays validated here will provide a valuable tool for research on the health, welfare, and conservation of giraffes. Electronic supplementary material The online version of this article (doi:10.1186/s12917-016-0864-8) contains supplementary material, which is available to authorized users.

A monoclonal antibody specific for the T1 tegumental antigen of Fasciola hepatica was used as a solid-phase immunosorbent for the purification of T1 antigen from homogenised mature F hepatica. Material fractionated by this technique was successfully used in enzyme-linked immunoassays to detect antibodies to F hepatica in sera from sheep and cattle. Species differences in response to infection by F hepatica were demonstrated.

We have developed highly sensitive enzyme immunoassays for total anti-HBc and anti-HBc IgM using the sequential saturation test principle resp. the anti-μ technique. A high practicability is achieved not only by short but also by identical incubation times in both assays which facilitates the mechanisation of the procedure.

Endourethral or endocervical swabs were taken from 403 patients to detect Chlamydia trachomatis by four different methods including standard tissue culture. Two immunoenzyme assays, Chlamydiazyme and IDEIA, were found to be satisfactory and could be valuable for large and busy sexually transmitted disease (STD) clinics.

Une infection par le virus HDV (hepatitis delta virus) est determinee par la detection d'un antigene de ce virus et d'un anticorps dirige contre ce virus. Deux methodes de detection avaient ete utilisees par Dubois et Goudeau: Dettassay (Noctech) et la technique immunoenzymatique Organon, le premier s'etant revele moins sensible que le second. Or, Shattock et Morris ont des resultats inverses. L'explication de ce phenomene reside probablement dans la matrice des reactifs utilises pour ces deux tests. En effet, le test Organon mis en pratique par Dubois et Goudeau a ete modifie par rapport au test d'origine. Les divergences de resultats peuvent donc s'expliquer de cette maniere

We used an enzyme immunoassay to determine the normal reference intervals for thyroxin, triiodothyronine, and thyrotropin in groups of children, ranging from newborns to 15-year-olds. Results compared well with those by radioimmunoassay. There were no substantial differences between plasma and serum samples for thyroxin and triiodothyronine, but thyrotropin concentrations differed significantly (p less than 0.05, n = 20 each).

One-step immunological incubation in enzyme immunoassays is a means of combining good performance characteristics with considerable savings in both handling time and disposables and a lesser chance of technical errors due to its simplicity. However, it must be emphasized that application of this principle has to be proven in each special case.

Rotaviruses (RV) are major causes of diarrheal disease in humans and other animals. Until recently, it was thought that all RVs shared a common antigen, and a vaccine based on this principle is undergoing field testing in humans. However, rotavirus-like agents (RVLA) which are morphologically indistinguishable from RVs but which do not share any antigenic similarity to standard RVs have recently been isolated from cows, piglets, birds, and humans. The role of these agents in human disease has not been extensively studied. We recently discovered a RVLA which is capable of infecting infant rats (J. Virol. 52:94-98, 1984). We found that fecal samples from adults and humans with acute gastroenteritis can transmit an identical disease to the infant rats. The infection is characterized by typical pathological changes in the gastrointestinal epithelial ceils and by the passage of viral particles with a characteristic pattern of double-stranded, segmented RNA. We have devised enzyme immunoassays for the detection of RVLA antigen and antibody. The application of these assays to human specimens has indicated that RVLA infection is common in young children and that infection with RVLA can be associated with severe gastroenteritis. RVLA may be an important new agent of gastroenteritis in humans and animals.

Recent advances in immunologic technology are making the rapid diagnosis of viral infections of the ocular surface possible. The prompt use of these diagnostic techniques can directly influence therapeutic decision making, such as the use of antiviral drugs and steroids. In this article, existing methods of sampling the ocular surface are discussed, and the yield of infectious virus and viral antigens from various sites on the ocular surface is reviewed. The immunologic principles underlying radio-immunoassays, enzyme immunoassays, and a variety of immunocytologic methods are outlined, along with the advantages and disadvantages of each immunologic technique. In addition to reviewing the methods for detecting viral antigens on the ocular surface, the value of assessing antiviral antibodies in the tear film, as well as prospects for future diagnostic techniques, are discussed.

The Homogeneous Enzyme lmmunoassays have in the past been used to determine drugs of abuse in urine. Later the system was expanded to include the quantitative determination of antiepileptic drugs in less than 1 min in microliters of serum or plasma. The Emit technology can also be used for the determination of digoxin. Recently a new principle was found which allows the determination of T-4 in serum or plasma. When T-4 is conjugated to pig mitochondria1 malate dehydrogenase, the enzymatic activity is inhibited. Upon addition of anti T-4 antibodies, the enzyme becomes reactivated. This system has been used to develop an Emit T-4 assay employing the ABA-100 as analyser. It was evaluated in 5 laboratories. A good correlation coefficient with existing methods was found. The coefficient of variation for all concentrations is below 5%. Recovery of added T-4 between 94 and 100% is found. More than 70 samples/h can be dealt with.

To the Editor.— The most common risk factors for women with human immunodeficiency virus (HIV) infection in the United States are intravenous drug abuse and heterosexual contact with persons at risk. 1 Some women, however, are unaware that their sexual partners belong to a high-risk group. For these reasons, we offered screening for antibodies to HIV to all women presenting for prenatal care at our clinic for indigent patients from Dec 12, 1987, to March 12, 1987. Study.— A questionnaire asking for known HIV risk factors was administered. Women were considered seropositive if results of two enzyme immunoassays for antibodies to HIV and a confirmatory Western blot analysis were positive. After counseling and obtaining informed consent, 299 of 302 women were screened. Overall, two (6.7 per 1000) of these women were seropositive. Of 39 women reporting one or more risk factors, one (25.7 per 1000) was seropositive. Of the 250 women

Diagnostic of H.pylori infection requires several methods, some of them are currently used in “Institut Pasteur “of Algeria. The aim of this study is to evaluate performances of two enzyme immunoassays used in detection of H.pylori using stool Ag before and after eradication, the first one “premier Platinium HpSA, Meridian Diagnostics” use a polyclonal Ac, the other one “IDEA HpStAR, Oxoid” use a monoclonal Ac. The reference test used in this study was UBT which is considered as a gold standard. More than 1000 stools specimens were studied prospectively between 2000 and 2008, in adult subjects which are more than 16 years old. For each patient two Stools specimens are used, one before eradication and one minimum 04 weeks after treatment. 749 stools specimens were collected before eradication and only 265 ones after. Our findings show that “IDEA HpStAR, Oxoid” results (specificity: 83%, sensibility: 91% before eradication, 83% after eradication) are better than “Premier Platinium HpSA®, Meridian Diagnostics” ones (specificity: 76%, sensibility: 64% before eradication, 56% after eradication). It seems evident that using monoclonal Ac gives more performances to the method, and allows detection of active infection with less of “false positive” also before than after eradication.