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A M Deelder

Publications and source records attributed to A M Deelder.

At least 91 records · Page 5Linked to original sources
PubMed1994

Rapid diagnosis of schistosomiasis by antigen detection in urine with a reagent strip.

For the rapid and simple diagnosis of schistosomiasis, a reagent strip assay for detection of circulating cathodic antigen (CCA) in urine was developed. The test was based on a previously developed sandwich enzyme-linked immunosorbent assay (ELISA) using a combination of two anti-CCA monoclonal antibodies. For the reagent strip assay, as the capture matrix, monoclonal antibody was coated onto a nitrocellulose membrane and mounted on polyvinyl chloride strips. Urine samples were then tested in an assay consisting of a combined incubation step of the urine sample and biotinylated detecting antibody followed by incubation in streptavidin peroxidase and a subsequent staining. The specificity and the sensitivity of the assay, as determined with urine samples of 61 uninfected controls and 67 Schistosoma mansoni-infected individuals, were 96.7 and 95.5%, respectively. The results of the reagent strip assay compared very well with microscopical parasitological diagnosis by the standard Kato-Katz method for the same individuals. The reagent strip test has a lower detection limit of 1 ng of CCA per ml and can be completed in 75 min. By the inclusion of two reference bands on the strips, standardized reading could be achieved. This reagent strip assay is a promising tool for qualitative diagnosis of S. mansoni infections in control programs.

Animals↗
PubMed1994

Immunologic characterization of two monoclonal antibodies reactive with repetitive carbohydrate epitopes of circulating Schistosoma mansoni egg antigen.

A panel of 60 monoclonal antibodies (MAbs) reactive with repetitive epitopes of species-specific Schistosoma mansoni soluble egg antigen (SEA) was tested for performance in detecting circulating egg antigens. Two MAbs, 114-5B1-A and 114-4D12-A, which were highly reactive with two different repetitive carbohydrate epitopes of soluble egg antigen, were found to detect circulating egg antigen in the sera of S. mansoni-infected mice. The two MAbs also showed strong reactivity with two high M(r) cercarial antigens present on the cercarial and schistosomular surface, while in the adult worms, antigens in the parenchyma were recognized. In two sandwich enzyme-linked immunosorbent assays (ELISA-5B1 and ELISA-4D12), each MAb was used as capture antibody and as conjugate, which resulted in assays with a lower detection level (0.2-0.4 ng) of the trichloroacetic acid-soluble fraction of soluble egg antigen (SEA-TCA)/ml. The antigen component(s) detected by ELISA-5B1 and ELISA-4D12 were 10,000 and 40,000 times more concentrated in the egg antigen than in the adult worm antigen, respectively. With both assays, in serum of heavily S. mansoni-infected mice, antigen became detectable from eight weeks postinfection (PI) onwards, with a striking increase at nine weeks PI.

Animals↗
PubMed1994

Quantitative determination of circulating soluble egg antigen in urine and serum of Schistosoma mansoni-infected individuals using a combined two-site enzyme-linked immunosorbent assay.

Two enzyme-linked immunosorbent assays (ELISA-5B1 using monoclonal antibody [MAb] 114-5B1-A [IgG1] and ELISA-4D12 using MAb 114-4D12-A [IgG3]) that detect circulating soluble egg antigen (CSEA) of Schistosoma mansoni were combined into one assay. This assay showed better performance than either of the two MAbs alone in detecting egg antigen, which was demonstrated with 80 urine samples from patients infected with Schistosoma mansoni from Zaire. The lower detection limit of the combined ELISA was 90 pg of the trichloroacetic acid-soluble fraction of soluble egg antigen (SEA-TCA) per milliliter. Thirty-two serum samples and 107 urine samples from uninfected Dutch individuals were negative when tested with the combined ELISA. This assay showed the same sensitivity (86.3%) with patients' urine samples as parallel testing with ELISA-5B1 and ELISA-4D12 (85%), while ELISA-5B1 and ELISA-4D12 showed sensitivities of 81.3% and 75%, respectively. The sensitivity of the combined ELISA with 51 serum samples was 84.3%, and three of five serum samples available from the seven patients with negative urine were positive for CSEA. The concentration of CSEA calculated from a four-parameters logistic curve for samples tested showed a correlation with egg output and serum circulating anodic antigen (P < 0.0001). Circulating soluble egg antigen in urine showed a significant decrease with an increase in age of the patients in relation to serum CSEA and egg output.

Age Factors↗
PubMed1994

Immunofluorescent visualization of the excretory and gut system of Schistosoma mansoni by confocal laser scanning microscopy.

Conventional epifluorescence microscopy (CEM) and confocal laser scanning microscopy (CLSM) were used to visualize the excretory system and the gut on whole organisms of different life-cycle stages of Schistosoma mansoni. To visualize the gut system, an anti-circulating anodic antigen (CAA) monoclonal antibody (MAb) (120-1B10-A) was used, whereas the excretory system was immunohistochemically stained with an anti-flame cell MAb (51-4H8-A) and with a recently described anti-egg MAb (114-5B1-A). The CEM procedure resulted in clear images at low magnification but the signal-to-noise ratio on the higher magnification images was very poor. Using CLSM on the adult worm, the 114-581-A MAb demonstrated a well-defined system of canals that could be morphologically identified as the excretory system. The flame cells terminating the branches of the excretory canals showed a clear immunoreactivity with the 114-5B1-A MAb as well as with the specific flame cell MAb. The gut system could be visualized, using an anti-CAA MAb, as two well-defined bands throughout the length of the parasite. Application of the 114-5B1-A MAb on cercariae revealed a strong fluorescence on the cercarial surface, whereas no immunoreactivity could be detected on internal structures. Whole eggs showed a bright fluorescence of the egg shell, whereas miracidia showed immunoreactivity of the germinal cells located in the center of the organism. The CLSM procedure, especially with the recently introduced fast photon-counting option, provides a superior tool to investigate the three-dimensional localization of different epitopes on immunofluorescently stained whole mounts of multicellular organisms in comparison with CEM.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Analysis of the target epitopes recognized by two monoclonal antibodies directed to egg-associated fractions of Schistosoma japonicum].

Two IgM isotype monoclonal antibodies (McAb), 2H10 and 2H1, recognizing repetitive epitopes on Schistosoma egg-associated molecules were characterized and their specificities were identified in a two-site sandwich ELISA system. In consistent with the differences in immunological behaviour and specificity demonstrated with immunoelectrophoresis (IEP) and immunofluorescent antibody (IFA) techniques, absolutely negative reactions found in the heterologous detecting system with alternated capture and detecting McAbs of the two revealed a complete incompatibility giving evidences that epitopes on different molecules were recognized. Immunological liability of the target antigen SEA or SEA-TCA to the two McAbs were demonstrated on sodium periodate and trifluoroacetic acid treatment indicating the biochemical nature of these epitopes were glycosyolated molecules with apparently higher resistance to the oxidizing agent showing in 2H10 recognizing epitopes. By means of an ion-gradient Mono-Q FPLC system (Pharmacia), 2H10-reactive epitopes of SEA, being tested not so efficiently adsorbed by ConA-sepharose affinity column, was found successfully concentrated in the profile eluted with pH 8.0 PBS at 0.2-0.4 NaCl ionic strength. Repeated trials on SDS-PAGE and Western blotting analysis with the reactive fractions further showed a heterogeneity of molecular weight range as well as the non-transferable property of the CHO-reactive groups.

Animals↗
PubMed1994

Quantitative diagnosis of Schistosoma infections by measurement of circulating antigens in serum and urine.

Recent research on the detection of the schistosome circulating antigens, circulating anodic antigen (CAA) and circulating cathodic antigen (CCA), has greatly expanded the scope of applications. In the present paper aspects of assay development, in particular of highly sensitive assays and of field-applicable assays, are discussed. The progress in the use of CAA- and CCA-detection for diagnosis, follow-up of chemotherapy and sero-epidemiological studies is evaluated.

Animals↗
PubMed1994

Morbidity markers for Schistosoma haematobium infection.

A description is given of a field study design, including pretreatment and short and long-term posttreatment measurements, which is conducted as a case-control study among school children in Kaloleni District, Kenya, and Kilosa District, Tanzania, including 500 school children from each endemic setting. The aim of the study is to evaluate eosinophil cationic protein (ECP) in urine as a marker for Schistosoma haematobium morbidity by comparing levels of ECP in urine with S. haematobium egg counts in urine, level of excreted S. haematobium egg antigen in urine, microhaematuria and urinary tract pathology assessed by ultrasonography. Initial results have been promising and are now subject to an extensive evaluation. Strong training components and transfer of technology are included in the project, thus contributing to the strengthening of the research capacity of the collaborating African institutions. Simple non-invasive assays for ECP and excreted S. haematobium egg antigen could provide new tools for evaluation of chemotherapy effects and morbidity in urinary schistosomiasis, helping to understand the dynamic process of posttreatment resolution and reappearance of pathological changes.

Adolescent↗
PubMed1993

Schistosoma mansoni circulating anodic antigen but not circulating cathodic antigen interacts with complement component C1q.

Adult schistosome parasites, living in the blood vessels of their mammalian hosts, protect themselves against immune damage in a variety of ways. In addition to the tegument, the intestinal epithelium of the blood-feeding worms is permanently exposed to both the innate and the acquired immune system. In this study, we investigated whether the Schistosoma gut-associated antigens CAA and CCA (circulating anodic antigen and circulating cathodic antigen, respectively), which are excreted in relatively large quantities into the host's circulation, might play a role in evading complement attack. Of several complement components tested, only purified C1q showed significant binding to CAA, a negatively charged highly glycosylated glycoprotein. CCA, also highly glycosylated, but neutral or slightly positively charged, did not bind to C1q. CAA bound only to the collagen-like stalks of C1q and not to the globular heads. No detectable interaction of CAA with precursor human C1 was found and CAA did not induce activation of C1 in whole human serum as assessed by consumption of hemolytic C4 activity. Also CAA could not induce activation of precursor C1 in vitro. These results suggest that CAA behaves like a receptor for C1q, and might be involved in protecting the vulnerable schistosome gut against complement-mediated attack.

Animals↗
PubMed1993

Schistosoma mansoni: analysis of monoclonal antibodies reactive with gut-associated antigens.

The analysis of a series of monoclonal antibodies (mAbs) developed in our laboratory against gut-associated antigens of Schistosoma mansoni is described. It was found that mAbs that recognized epitopes of antigens in the gut and on the eggshell were mainly of the IgM isotype; these epitopes are likely to be carbohydrate in composition. Of a number of mAbs that were reactive with antigens important to the human humoral immune response, 75% appeared to be reactive with the circulating cathodic antigen.

Animals↗
PubMed1993

Epidemiology of Schistosoma mansoni infection in a recently exposed community in northern Senegal.

The epidemiology of Schistosoma mansoni infection was investigated in Ndombo, a village in the epicenter of a very recent outbreak of schistosomiasis in northern Senegal. Repeated fecal egg counts and antigen detection in urine and serum were carried out in a random population sample (n = 422). Eggs were found in 91% of the subjects, with 41% excreting > 1,000 eggs per gram of feces (epg) (mean egg load of 646 epg). The prevalence was almost 100% in groups greater than five years of age. In spite of the supposed absence of acquired immunity, intensities of infection decreased strongly in adults. Antigen detection confirmed the high prevalence and intensity of infection and the age-related distribution of worm loads. The emergence of this new focus is probably due to the ecologic impact of newly built dams and the extension of irrigation projects in the Senegal basin.

Adolescent↗
PubMed1993

Dot immunoassay with biotinylated antigen for determination of antibodies against the circulating cathodic antigen (CCA) in schistosomiasis japonica.

Based on the fact that schistosomiasis patients in both the acute and chronic phase of the infection show a strong humoral immune response against the gut-associated circulating cathodic antigen, a simple and sensitive dot immunobinding assay for schistosomiasis japonica was developed. Circulating cathodic antigen that had been purified by immunoadsorption using monoclonal antibody was biotinylated with biotin aminocaproylhydrazide via the carbohydrate moiety of the antigen. Serum samples dotted onto nitrocellulose strips were then tested in an assay involving a combined incubation step of biotinylated antigen and streptavidin peroxidase, and a subsequent staining; the total assay time was 1.5 hr. Assaying the sera of 105 uninfected controls and 104 Schistosoma japonicum-infected individuals showed a specificity of 99.0%, and sensitivities of 96.2% (acute infections) and 94.1% (chronic infections). The described assay is economic, rapid, and reproducible and lends itself to use under field conditions.

Animals↗
PubMed1993

Diagnostic evaluation of dot-binding assays for circulating cathodic antigen (CCA) and anti-CCA determinations in schistosomiasis japonica using defined biotinylated conjugates.

Using an affinity purified circulating cathodic antigen (CCA) preparation and an anti-CCA monoclonal IgM antibody, we modified dot-binding assays for anti-CCA and CCA detections with biotinylated conjugates. A study on 3 groups of 138 schistosomiasis japonica patients and 105 healthy individuals demonstrated a high predictive rate of over 95% in both assays, highly comparable to those of circumoral precipitin test (COPT). A blind test in 342 samples of various groups revealed higher detection rates in Ab-binding assay with both acute and chronic case groups (over 90%), but comparatively lower rates in Ag-binding assay with chronic groups (50%-76%). Distinct reductions of either GMRT and dot-indexes were found in 48 praziquantel treated patients whose sera were collected 9 months after chemotherapy. The major target molecules detected by the two binding assays were proved to be the protein incorporated moieties readily precipitated by trichloroacetic acid (TCA), ammonium sulphate and higher concentration of polyethylene glycol (PEG) suggestive of pathological, specific immunoglobulins in the free or complex forms. Non-specific dot reactions were found in some acute and chronic patients with non-relevant bovine serum albumin (BSA) conjugated peroxidase and streptavidin-PO controls, and also in normal sera with the McAb peroxidase conjugate or when working concentration of the biotinylated McAb was not properly titrated. The reliability and proper management of the dot binding assay as an immunodiagnostic tool were discussed.

Animals↗
PubMed1993

Detection of IgM antibodies directed against the gut-associated circulating cathodic antigen in sera from Schistosoma mansoni infected patients. Development and comparison of three enzyme-linked immunoassays.

The majority of the human IgM antibodies detected with an immunofluorescence assay (IFA) on adult worms are directed against the gut-associated circulating cathodic antigen (CCA). In order to study this phenomenon further we developed and evaluated three related ELISA methods to specifically detect IgM antibodies against purified CCA. The assays employed: 1) direct coating of CCA, 2) indirect coating of CCA via a monoclonal antibody, and 3) IgM antibody-capture by rabbit anti-mu chain antibodies. Using a group of 46 positive sera, it was found that the three ELISA's and the IFA were significantly correlated. To discriminate between positive and negative sera we used a cut-off level of average reactivity + 3 standard deviations of 50 negative sera. False negative reactions were not found in any of the ELISA's, while both in the direct and indirect ELISA one false positive reaction occurred. For further studies or diagnostic use the antibody-capture ELISA is recommended.

Animals↗
PubMed1992

Magnetic bead antigen capture enzyme-linked immunoassay in microtitre trays for rapid detection of schistosomal circulating anodic antigen.

We have developed a new magnetic bead antigen capture enzyme-linked immunoassay for the detection of schistosomal circulating anodic antigen. The assay utilizes IgG1 monoclonal antibody coated monodisperse magnetic beads in microtitre trays fitted to a special magnet. The total test time was found to be 1-2 h, using 0.05 mg beads per well. The lower detection level was 0.7 ng AWA-TCA per ml (approximately 0.07 ng CAA per ml). Validation by sera from uninfected and Schistosoma mansoni infected Africans and Norwegians resulted in an assay specificity of 100% and sensitivity was close to 90% for cases excreting more than 100 eggs per gram faeces. At such clinically relevant levels the inter-assay CV was below 10% and photometric absorbance correlated to antigen levels was nearly linear. There was a significant correlation between the magnetic bead EIA absorbance values and the titres obtained using the previously established ELISA. The new bead assay, however, was easier and less laborious because TCA pretreatment and the titration of positive results were unnecessary.

Africa↗
PubMed1992

Detection of circulating anodic antigen before and after specific chemotherapy in experimental murine Schistosomiasis mansoni.

In two groups of mice infected with 60 (group I) and 120 (group II) Schistosoma mansoni cercariae, respectively, the effects of intensity and duration of infection, and of praziquantel therapy (curative vs subcurative dose) on the levels of circulating anodic antigen (CAA), were studied. CAA was measured in trichloracetic acid-treated serum samples with an avidin-biotin enzyme-linked immunosorbent assay (AB-ELISA) using the monoclonal anti-CAA antibody. Total worm burdens, oogram patterns and ova counts/g liver and intestine were followed up. The lowest detectable level of CAA was about 1.0 ng/ml, and was positive with a worm load of 3-5/mouse. CAA levels became already detectable as early as 1-2 weeks post-infection (pi) before any parasitological parameter and showed a significant drop from the 11th-12th week pi onwards. A positive correlation was demonstrated between the CAA level and worm load. Following successful praziquantel therapy, CAA disappeared earlier than any of the other parameters studied.

Animals↗
PubMed1992

The susceptibility of adult schistosomes to immune attrition.

Mouse infection models are described that demonstrate reduction of egg production in Schistosoma haematobium infections and both worm loss and reduced fecundity in S. bovis infections. Neither phenomenon could be shown in S. mansoni infected mice. The immunological basis for these anti-adult responses was inferred by comparison with infections in T-cell deprived mice and by serum transfer of the ability to reduce a S. bovis worm burden into immunocompromised hosts. Vaccination with irradiation attenuated parasites was also shown to have consequences for the adults of a challenge infection of S. haematobium and S. bovis specifically. Prior vaccination resulted in an abrogation of the anti-fecundity and adult worm elimination that occurred in non-vaccinated similarly infected mice. These models are being used to define the targets and mechanisms involved in anti-adult attrition. A serological assay, quantitation of a circulating antigen (CAA) has been assessed for its ability to measure worm burdens of different species of schistosome in mice. This assay will be used to question whether anti-adult immunity contributes to the pattern of infection with S. mansoni and S. haematobium in man.

Animals↗