Isolation and identification of a Giardia lamblia-specific stool antigen (GSA 65) useful in coprodiagnosis of giardiasis

Rosoff, J D; Stibbs, Henry H.

doi:10.1128/jcm.23.5.905-910.1986

Cited by 68 publications

(33 citation statements)

References 24 publications

(18 reference statements)

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“…Because of this, diagnosis by microscopy is not entirely reliable (26); and there is a need for a rapid, stable, and highly sensitive assay for the detection of cell-free giardial antigens in stool specimens. Antigen-detection assays involving counterimmunoelectrophoresis (4,15,24) and antigen-capture enzyme-linked immunosorbent assay (ELISA) have previously been reported (9,11,20,23). Our previously reported polyclonal antibody-based assay (20) was 92% sensitive; prior fixation of stool specimens in 10% Formalin was found to have no detrimental effect on the ability of that assay to detect the antigen.…”

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confidence: 85%

Monoclonal antibody-based enzyme immunoassay for Giardia lamblia antigen in human stool

Stibbs

1989

J Clin Microbiol

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A visually readable monoclonal antibody-based antigen-capture enzyme immunoassay for the detection of Giardia lamblia antigen in human stool specimens was developed and found to be 97% (30 of 31 stool specimens) sensitive for formalinized stools and 82% (49 of 60 stool specimens) sensitive for unfixed stool specimens by visual reading. The storage of specimens in 10% Formalin resulted in increased absorbance in 20 of 26 G. lamblia-positive specimens tested as both formalinized and unfixed specimens; the increase averaged 1,336%. The assay was specific for antigens of this organism and for antigens derived from the cyst, as opposed to the trophozoite, stage. The assay could detect the antigens of five cysts per well, but could not detect antigen in in vitro-cultured trophozoites. A mouse monoclonal antibody of the immunoglobulin Gi (IgGl) subclass, which was prepared against cysts of G. lamblia, was used as the solid-phase capture antibody. The antibody was reactive with the cyst wall, as determined by immunofluorescence. Polyclonal rabbit anti-cyst IgG was used as the secondary antibody, and peroxidase-labeled goat anti-rabbit IgG was used as the tertiary antibody in the assay format. Maximal capture of antigen from stool specimens occurred by 30 min. Optimal dilution of specimens was in the range of 1:60 to 1:600. Preliminary characterization of affinity-purified antigen recognized by the monoclonal antibody showed that it is heat stable (100°C, 12 min) and resistant to sodium periodate treatment and that it may exist in multiple molecular weights from 45,000 to 110,000.

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confidence: 85%

Monoclonal antibody-based enzyme immunoassay for Giardia lamblia antigen in human stool

Stibbs

1989

J Clin Microbiol

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“…This procedure was done based on studies of Rosoff and collaborators (Rosoff and Stibbs, 1986). Briefly, the sediments were solved in 0.5% tween 80 solutions followed by centrifugation at 700 g for 5 min and solving and centrifugation processes were repeated periodically till the surface liquids were cleaned.…”

Section: One-phase Sucrose Gradientmentioning

confidence: 99%

“…Routine method to diagnose giardiasis is direct microscopic examination of stool (Rosoff and Stibbs, 1986;Duque-Beltran et al, 2002). Sensitivity of microscopic method even with several times repeating of each test is just 50 to 70% (Burke et al, 1975(Burke et al, , 1977.…”

Section: Introductionmentioning

confidence: 99%

Introducing a simple and economical method to purify Giardia lamblia cysts

Barazesh¹,

Majidi²,

Fallah³

et al. 2011

Afr. J. Biotechnol.

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Direct microscopic examination of stool to diagnosis giardiasis (wet mount) has low diagnostic value, but immunologic methods (like IFA and especially ELISA) that are based on the determination of parasite antigens in fecal samples (antigen detection) have relatively high sensitivity and specialty. To prepare anti-Giardia lamblia antibodies needed to design diagnostic kits as well as parasite culture and other molecular studies, we require purification of the parasite cysts. In this study, we designed a rapid, simple and inexpensive method to purify parasite cysts from fecal samples of the patients suffering from giardiasis. Initially, fecal samples that the presence of G. lamblia in them was affirmed by direct microscopic observation of cysts were subjected to various purification methods like one-and twophase sucrose gradient isolation, percoll-sucrose gradient isolation, and a modified two-phase method run by 0.85 and 1.5 M sucrose. The first procedure contained some contents of bacteria and small particles of feces. In the second and third procedure, bacteria were almost removed and the cysts were intact but the suspension contained some extras and cellulose particles. The recovery rate for modified two-phase method was 1.5 × 10 4 cysts for each two grams of fecal sample. In this study, by using and comparing with the results of some other studies, we introduce and run a modified method that in fact is a mélange of them with some changes. So this method could be recommended as a fast, advantageous and simple method in purification of G. lamblia cysts.

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“…The ELISA-GSA 65 detects a G. duodenalis-specific antigen (GSA) that is excreted in the stool. GSA has been identified in trophozoites and cysts and has an approximate molecular mass of 65 kDa (162). The ELISA-GSA 65 is available commercially as a kit, and its sensitivity and specificity are comparable to those of microscopic examination for cysts in the stool (62,163).…”

Section: Detection Of Antigens In Fecesmentioning

confidence: 99%

“…In fact, all studies with the ELISA-GSA 65 have reported a greater sensitivity of the immunodiagnosis assay over the microscopic examination of a single specimen ( Table 1). The sensitivity of the assay varies between 95 and 100%, and 100% specificity has been reported when it was used with stools from patients infected with other intestinal parasites (15,162). It has been reported that the ELISA-GSA 65 can detect Giardia infection in at least 30% more cases than the microscopic examination (163).…”

Section: Detection Of Antigens In Fecesmentioning

confidence: 99%

Immune Response toGiardia duodenalis

Faubert

2000

Clin Microbiol Rev

112

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SUMMARY The intestinal protozoan Giardia duodenalis is a widespread opportunistic parasite of humans and animals. This parasite inhabits the upper part of the small intestine and has a direct life cycle. After ingestion of cysts, which are the infective stage, the trophozoites emerge from the cysts in the duodenum and attach to the small intestinal mucosa of the host. Since the migration of trophozoites from the lumen of the intestine into surrounding tissues is an unusual occurrence, the immune response to Giardia remains localized. The identification of antigens that play a role in acquired immunity has been difficult because of the occurrence of antigenic variation and because, Giardia being an ubiquituous organism, it is possible that the antigenic profiles of isolates from different geographic areas will vary. Innate-immunity mechanisms play a role in the control and/or severity of the infection. Both humoral and cell-mediated immune responses play a role in acquired immunity, but the mechanisms involved are unknown. A variety of serological assays have been used to detect circulating antibodies in serum. Because of the biological characteristics of the parasite and the lack of suitable antigens, the sensitivity of serological assays remains poor. On the other hand, detection of antigens in feces of infected patients has met with success. Commercial kits are available, and they are reported to be more sensitive than microscopic examination for the detection of giardiasis on a single specimen.

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Isolation and identification of a Giardia lamblia-specific stool antigen (GSA 65) useful in coprodiagnosis of giardiasis

Cited by 68 publications

References 24 publications

Monoclonal antibody-based enzyme immunoassay for Giardia lamblia antigen in human stool

Monoclonal antibody-based enzyme immunoassay for Giardia lamblia antigen in human stool

Introducing a simple and economical method to purify Giardia lamblia cysts

Immune Response toGiardia duodenalis

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