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PubMed1993

A comparison of ELISA, FAST-ELISA and gel diffusion tests for detecting antibody to equine infectious anaemia virus.

Sera of sixteen horses with clinical signs of EIA from six different outbreaks and sera of 100 uninfected horses were used to validate an ELISA for EIA diagnosis. The antigen used was a recombinant protein derived from the amino-terminal portion of the transmembrane envelope protein of EIA (gp45). Reactivity between positive and negative sera could be clearly distinguished. Comparison with the traditional agar gel immunodiffusion test (commonly called the Coggins test) showed that the ELISA was superior in sensitivity. Comparison of this ELISA with the FAST-ELISA system showed that the latter was less sensitive. Although the FAST-ELISA was much faster to perform, it could not be recommended as a diagnostic test in its present form, because the margin between reactivity by a positive serum and a negative serum was not high.

Animals↗
PubMed2005

Comparison of IgG-ELISA and IgG4-ELISA for Toxocara serodiagnosis.

Diagnosis of human toxocariasis, caused by Toxocara canis or Toxocara cati, normally relies on a combination of the presence of clinical signs and symptoms backed by positive serology. The use of Toxocara excretory-secretory antigen (TES) in ELISA assays increases the test specificity. However, in tropical countries where soil-transmitted helminths are endemic, cross-reactivity from antibodies to these intestinal parasites poses a significant limitation for Toxocara serodiagnosis. To increase the specificity of serodiagnosis, we compared the use of IgG-ELISA to the use of IgG4-ELISA using commercially manufactured TES-coated plates. The sensitivity of the IgG-ELISA was 97.1%, while that of the IgG4-ELISA was 45.7%; the specificities were 36.0 and 78.6%, respectively. The study shows that employing both assays can improve the serodiagnosis of toxocariasis. An IgG4 immunoassay would also be useful in the secondary screening of antigen clones in the effort to develop improved serological tests for toxocariasis.

Animals↗
PubMed2000

Diagnosis of pemphigus by ELISA: a critical evaluation of two ELISAs for the detection of antibodies to the major pemphigus antigens, desmoglein 1 and 3.

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are characterized by autoantibodies to the desmosomal glycoproteins desmoglein 3 (Dsg 3) and Dsg 1 (Dsg 1), respectively. In this study, two enzyme-linked immunosorbent assays (ELISA) which detect IgG autoantibodies to Dsg 1 and Dsg 3 have been evaluated. A total of 317 normal and disease controls, 82 patients with PV and 25 with PF were studied. The Dsg 3 ELISA was positive in all 34 patients with untreated PV and the Dsg 1 ELISA was positive in all 10 with untreated PF. When patients undergoing treatment were included, the sensitivities fell to 95% and 92%, respectively, but still compared favourably to the sensitivity of indirect immunofluorescence which was 79% in PV and 84% in PF. All PF sera were negative in the Dsg 3 ELISA and the specificity of both assays was 98% or greater. Large numbers of samples could be analysed simultaneously over a relatively short time period. The Dsg 1 and Dsg 3 ELISAs also provided objective, quantitative, reproducible data which allowed differentiation of PV from PF and in view of these advantages, they are likely to become a routine technique in diagnostic laboratories.

Adolescent↗
PubMed2003

Comparison of capture immunoglobulin M (IgM) and IgG enzyme-linked immunosorbent assay (ELISA) and nonstructural protein NS1 serotype-specific IgG ELISA for differentiation of primary and secondary dengue virus infections.

We have found that NS1 serotype-specific immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) can be used to differentiate primary and secondary dengue virus infections. This is due to the fact that the NS1-specific IgG antibody cannot be detected before day 9 of illness for primary infection, so the NS1-specific IgG antibodies measured in acute-phase sera must come from previous infection. Comparison of NS1 serotype-specific IgG ELISA with envelope- and membrane-specific capture IgM and IgG ELISA in the differentiation of primary and secondary dengue virus infections showed good correlation (95.90% agreement). Most important, we have found that the serotype of the dengue virus from the majority of patients with primary infection could be correctly identified when convalescent-phase or postinfection sera were analyzed by NS1 serotype-specific IgG ELISA. These findings suggested that NS1 serotype-specific IgG ELISA could be reliably applied for serodiagnosis and seroepidemiological study of dengue virus infection.

Acute Disease↗
PubMed2006

Assessment of a bovine viral diarrhea virus antigen capture ELISA and a microtiter virus isolation ELISA using pooled ear notch and serum samples.

To reduce the cost of whole herd screening for bovine viral diarrhea virus persistently infected animals, the sensitivity and specificity of an antigen-capture enzyme-linked immunosorbent assay (AC-ELISA) and a microtiter virus isolation ELISA using saline from ear notch samples or pooled serum was determined. Pooled saline from ear notch samples, assayed by AC-ELISA, gave a sensitivity and specificity of 98% and 94%, respectively, for pools containing 2 samples and 72% and 100%, respectively, for pools of 5. The sensitivity of pooled ear notch or serum samples for bovine viral diarrhea virus detection by microtiter virus isolation (sensitivity < 5%) or serum samples for detection by AC-ELISA (sensitivity < 15%) is too low to be used for whole herd screening. Pooling saline from ear notch samples from 2 animals tested by AC-ELISA, however, could provide a less expensive, reliable method for whole herd screening for bovine viral diarrhea virus.

Animals↗
PubMed1992

Follow-up of multibacillary leprosy patients using a phenolic glycolipid-I-based ELISA. Do increasing ELISA-values after discontinuation of treatment indicate relapse?

With the introduction of reproducible serological tests it was hoped that relapses in leprosy patients, after discontinuing treatment, could be detected before damaging reactions occurred and before the patients became infectious. The possible value of an ELISA using a semisynthetic analogue of phenolic glycolipid-I to detect antibodies to this antigen in order to predict a relapse in multibacillary patients was investigated. In contrast to that reported for paucibacillary patients, this test was useful to detect early relapses in multibacillary patients. In 3 out of 4 multibacillary patients who relapsed, the ELISA-values were increased. The decreased ELISA-values in the one relapsed patient could be attributed to the corticosteroid therapy. In the multibacillary patients who did not relapse after RFT, the ELISA-values were consistently low or decreased. In only one patient did the ELISA-values increase following his release from treatment and this patient was clinically suspected of developing a relapse.

Adult↗
PubMed1999

The combined IGG, IGM and IGA peroxidase conjugate can facilitate determination of immune complexes by CIF-ELISA and anti-C3 ELISA.

To determine the levels of circulating immune complexes (CIC) in normal and patients sera, CIF-ELISA and anti-C3 ELISA were performed. Immune complexes containing different antibody isotypes were detected simultaneously by the combined anti human IgG, IgM and IgA peroxidase conjugate as detecting antibody. The results obtained confirm the higher CIF-ELISA sensitivity, specificity and reproductivity compared to anti-C3 ELISA and provide good evidence to justify the use of CIF-ELISA as a screening test for CIC assessment.

Antigen-Antibody Complex↗
PubMedDate not supplied

[Diagnostic use of ELISA, IgG, IgM, IgA and ELISA IgG avidity in recent and chronic toxoplasmosis].

Toxoplasmosis, a world-wide zoonotic infection, is generally asymptomatic and benign in immunocompetent individuals, but it can be serious in immunodeficiencies particularly in patients with acquired immunodeficiency syndrome and in children infected in utero. So, it is important to dispose methods which permit discriminate between recent and chronic infections. In order to contribute to improve the diagnosis of toxoplasmosis ELISA IgG, IgM, IgA and ELISA IgG avidity were performed in 15 and 24 sera from patients suspected of having acute and chronic infection respectively, according dye test (DT) titres. ELISA IgG was positive in both groups, ELISA IgM was positive in 78.6 and 58.3% respectively, while ELISA IgA was positive in 85.7 and 33.3% of recent and chronic group respectively. In those sera with low IgG avidity (18.8%) we found specific IgM in 71.5 and 4.2% and IgA in 78.6 and 0.0% of recent and chronic groups respectively. Parallelling, 208 sera samples were classified according to the results of DT, indirect hemagglutination and complement fixation tests in the following groups: acute (97), intermediate (36), chronic (35) and negative (40). The results were: acute (96.9-64.9-55.6 and 65.9%); intermediate (97.2-63.8-44.4 and 47.2%); chronic (45.7-42.8-5.7 and 34.3%) for IgG, IgM, IgA and low IgG avidity respectively. The use of both acute markers, IgA and low IgG avidity in the diagnosis of toxoplasmosis is discussed.

Animals↗
PubMed2005

Development of the rapid and simplified ELISA (WHOLE BLOOD-ELISA) using samples of Schistosoma japonicum-infected human whole blood.

An ELISA technique was developed using samples of Schistosoma japonicum-infected human whole blood based on the conventional ELISA. In this study, the following were demonstrated. 1) Whole blood samples could be used. 2) The volume of whole blood and conjugate could be reduced to 0.05 ml. 3) The incubation time was shortened to 5 minutes. 4) The optical density could be measured at 10 minutes after transferring the substrate and the volume was reduced to 0.1 ml. 5) It did not require a fixed temperature setting. 6) The operation time was as short as 20 to 30 minutes. 7) The optical density values were almost the same as the conventional ELISA and were not influenced by other common intestinal helminthic infections. 8) The observed variations from day to day including effects of sampling in stool examination were negated by the results of this ELISA technique. 9) Based on correlation with stool examination results, criteria can be formulated in which optical density values of 0.3 and above as positive, 0.1 to less than 0.3 as doubtful, and less than 0.1 as negative. Whenever an immunological field survey is necessary, before and after a selective or a mass treatment control program, this WHOLE BLOOD-ELISA, which was shown to be rapid and simple, is recommended.

Adolescent↗
PubMed2001

[Development of the ELISA kit for the detection of Hypoderma bovis antibodies in cattle. III. Stability and usefulness of ELISA components preserved under different conditions].

The aim of investigations was to determine the stability of ELISA components preserved under different conditions. The following components for the ELISA were used: the secreted/excreted antigen prepared from H. bovis L1 larvae, its fraction containing hypodermine A, conjugat, positive and negative control sera. Freezing at -20 degrees C, lyophilization and preservation at 4 degrees C were applied. Seven kits for the ELISA containing components preserved using described methods, were prepared. The identical packets of sera were examined by the ELISA directly after preparation of the kits (day '0'), and next, at 3-4 week intervals for 9 months. The experiments showed that the best method of conservation of ELISA components for the detection of H. bovis antibodies was lyophilization. The kits prepared in this way did not lose their characteristics for 9 months and their specificity and sensitivity were close 100%.

Animals↗
PubMed1991

A comparative efficacy of plate ELISA and dot ELISA to detect antiamoebic antibodies in clinical patients.

The dot enzyme-linked immunosorbent assay (dot ELISA) has been developed and compared with plate ELISA for detecting antiamoebic antibodies in serum samples from amoebic patients and healthy controls. Both dot and plate ELISA detected antiamoebic antibodies in all 17 confirmed amoebic liver abscess cases and 15 (68%) of 22 suspected amoebic liver abscess cases while none of 21 non-amoebic hepatic disorders, 25 non-amoebic intestinal disorders and 28 apparently healthy subjects had antiamoebic antibodies as assessed by either of the tests. All the 15 suspected amoebic liver abscess patients who had antiamoebic antibodies responded favourably to antiamoebic treatment. As the dot ELISA is simpler, rapid, inexpensive, equally sensitive and specific as compared to plate ELISA, its use in detecting antiamoebic antibodies is recommended especially under field conditions.

Antibodies, Protozoan↗
PubMed1990

Dot-ELISA in detection of filarial antibodies: comparison with standard ELISA.

The present study deals with the preliminary results of two assays, standard ELISA and dot ELISA compared for their sensitivity in measuring humoral immune responses in filarial patients and normals residing in an area of bancroftian filariasis using a heterologous antigen. Responses were more vigorous in filarial patients than in endemic normals by both assays. Higher percentage of positivity and reciprocal titre of antibody were observed in dot ELISA showing more sensitivity than the standard ELISA. The dot ELISA method required only nanogram amounts of antigen.

Animals↗
PubMed1997

Detection of circulating antigens of Parastrongylus cantonensis in human sera by dot-blot ELISA and sandwich ELISA using monoclonal antibody.

A dot-blot ELISA was compared with a previously performed sandwich ELISA for the detection of Parastrongylus cantonensis antigens in sera from patients. Using the same monoclonal antibody and the same sera, 6 of 10 sera (60%) from parastronglyiasis patients were positive in dot-blot ELISA, whereas with sandwich ELISA, 5 of the same patient sera (50%) were positive. The specificity in both assays was 100% using 50 sera from patients with other parasitic diseases; of these, 10 each were from patients with cysticercosis, filariasis, gnathostomiasis, malaria and toxocariasis. The control group consisted of 53 sera from normal health Thais and Malaysians. The sensitivity of the assays was, however, slightly better with dot-blot ELISA and because it is simple, quick and cost-effective, it may be a test of choice for specific diagnosis of human parastrongyliasis.

Angiostrongylus cantonensis↗
PubMed1994

Potential use of IgG2-ELISA in the diagnosis of chronic elephantiasis and IgG4-ELISA in the follow-up of microfilaraemic patients infected with Brugia malayi.

Sera from fifty subjects with different presentations of Brugian filariasis and from common soil-transmitted helminth infections were tested for specific anti-filarial IgG and its subclasses. Anti-filarial IgG, IgG1 and IgG3 showed cross-reactivities with soil-transmitted helminthic infections and no significant differences in optical densities among the various groups of filarial patients. In comparison with other groups of subjects, IgG4-ELISA of sera from microfilaraemic patients and some previously microfilaraemic patients showed a significant increase in optical density readings, while IgG2-ELISA showed elevated optical density readings in sera of patients with chronic elephantiasis. Therefore IgG2-ELISA is potentially useful in the diagnosis of brugian chronic elephantiasis while IgG4-ELISA may be beneficial for follow-up diagnosis of treated microfilaraemic patients.

Animals↗
PubMed2005

Direct competitive ELISA based on a monoclonal antibody for detection of aflatoxin B1. Stabilization of ELISA kit components and application to grain samples.

A direct competitive enzyme-linked immunosorbent assay (ELISA) based on a monoclonal antibody has been developed and optimized for detection of aflatoxin B1 (AFB1), and an ELISA kit has been designed. This immunoassay was highly specific, sensitive, rapid, simple, and suitable for aflatoxin monitoring. AFB1 concentrations determinable by ELISA ranged from 0.1 to 10 microg L(-1). The IC50 value was 0.62 microg L(-1). Recovery from spiked rice samples averaged between 94 and 113%. The effect of different reagents on the stability of HRP-AFB1 conjugate solution was studied. The performance of a stabilized enzyme tracer in ELISA was determined and compared with that of a freshly prepared control solution of HRP-AFB(1) conjugate. The results showed that stabilizing media containing 0.02% BSA, 0.1% Kathon CG, and 0.05 mol L(-1) calcium chloride in 0.05 mol L(-1) Tris-HCl buffer (pH 7.2) maintained the activity of HRP-AFB1 at a dilution of 1:1000 for a period of at least 12 months at room temperature whereas the reference conjugate solution without the additives lost its activity within a few days. Several additives were tested for their stabilizing effect on a monoclonal antibody (MAb) immobilized on the surface of polystyrene microtitre plates. It was shown that immobilized MAb, treated with post-coating solutions containing PVA, BSA, and combinations of these substances with trehalose, retained its activity for at least 4 months at 4 degrees C, whereas the untreated MAb-coated plate lost its activity within 2 days.

Aflatoxin B1↗
PubMed1984

A sensitive enzyme-linked immunosorbent assay (ELISA) against the major EBV-associated antigens. I. Correlation between ELISA and immunofluorescence titers using purified antigens.

An enzyme-linked immunosorbent assay (ELISA) was developed for the major Epstein-Barr virus (EBV) associated antigens. The ELISA assay was based on purified protein components of virus-capsid antigen (VCA), early antigen (EA), membrane antigen (MA) and the nuclear antigen (EBNA). These antigens, except EBNA, were purified on immunoaffinity columns containing monoclonal antibodies, while EBNA was purified by biochemical methods. Screening of 69 human sera including 26 sera from individuals with infectious mononucleosis against these antigens in ELISA showed a good correlation with immunofluorescence titers against the major groups of EBV associated antigens. The results indicated that the ELISA technique using purified EBV proteins could be useful for detecting and monitoring antibody responses to different EBV proteins in patients with EBV-associated diseases.

Antigens, Viral↗
PubMed1994

The use of an indirect ELISA with protein G-peroxidase conjugate and a blocking ELISA to demonstrate recent bluetongue infection in sheep.

The humoral immune response of sheep infected with bluetongue virus serotypes 3, 9 and 16 was monitored by plaque inhibition (PI), blocking ELISA (BELISA) and indirect ELISA over a period of 63 days post-infection. Results indicated that testing of a single plasma or serum sample by both a BELISA and an indirect ELISA using a recombinant streptococcal protein G (PrG) peroxidase conjugate enabled an assessment of the proximity of a recent infection based on the failure of PrG to bind ovine IgM class antibodies. When BELISA and indirect ELISA results were expressed as a ratio, values indicative of recent infection (> or = 5) were observed for an average duration of 16.5 days (range 8 to 23 days) following the initial detection of antibody by BELISA. This approach has potential to improve diagnosis of a wide range of virus infections by providing an indicator for the relationship of serological status with a recent infection. However, where reinfection may occur, as with bluetongue virus, alternative methods may be required for definitive diagnosis.

Animals↗
PubMed1993

ELISAs for parasitologists: or lies, damned lies and ELISAs.

The introduction in 1971, by Engvoll and Perlmann, of enzyme labels in immunoassays represented a significant technical advance. Their enzyme-linked immunosorbent assay (ELISA) proved to be as sensitive as radioimmunoossoys but safer to use. Since then, ELISAs have been widely used in the assay o f anti-bodies and antigens. In this article, Pradhib Venkateson and Derek Wokelin focus on some o f the problems associated with ELISAs when applied to parasitic infections, which can modify antibody responses, by immunosuppression or polyclonal activation. The article also considers optimization, which is an essential step in the establishment o f on ELISA.

Journal Article↗