Biomedical subjects

Y Sbihi

Publications and source records attributed to Y Sbihi.

5 recordsLinked to original sources

PubMed2001

Comparative sensitivity of six serological tests and diagnostic value of ELISA using purified antigen in hydatidosis.

Most serodiagnostic techniques have been evaluated for diagnosis of cystic hydatid disease caused by Echinococcus granulosus. Each, to varying degrees, has been shown to give false results, with considerable variation between laboratories. The comparative study was made concerning the sensitivity of the immunodiagnostic methods based on 58 sera from hydatid disease with different cyst locations. Latex agglutination, immunoelectrophoresis (IEP), and specific IgE, IgG enzyme-linked immunosorbent assay (ELISA) tests were studied. Specific IgG ELISA AgB (antigen B-rich fraction) was the most sensitive test (96.5%) and the least sensitive tests were specific IgE ELISA (24.1%) and IEP (25.8%). The low sensitivity of these two tests was due partly to the low reactivity detected in the sera of patients with lung hydatidosis. Initial laboratory studies showed purified antigens to be preferable to crude cyst fluid, regardless of the type of test used. For this reason, we evaluated the sensitivity and specificity of ELISA by using the purified antigen-B-rich fraction. In all, 117 sera were examined: 78 sera from patients with hydatidosis surgically confirmed, 15 sera from healthy control subjects, and 24 sera from patients with diseases other than hydatidosis. The method gave good results: 93.5% sensitivity, 89.7% specificity, and 92.3% diagnostic efficacy.

Animals↗

PubMed2001

Western blot applied to the diagnosis and post-treatment monitoring of human hydatidosis.

The serologic diagnosis of hydatidosis (caused by Echinococcus granulosus) can be made by different techniques, although the lack of standardization of the antigens affects the sensitivity, specificity and concordance among the different tests. We have applied the Western-Blot (WB) technique, associated with a purified antigen from sheep hydatid fluid, at 60 samples of serum from 14 patients suffering echinococcosis in different bodily locations, monitored for 3 years. The WB test enabled the detection of antibodies in the pre-surgical samples for proteins of 12-14, 16, 20, 24-26, 34, 39 and 42 kDa in molecular weight in 15-96% of the patients. The combination involving 2 of the 3 proteins of 20, 39 and 42 kDa has made it possible to diagnose 100% of the cases. The antibodies specific to proteins 39 and 42 kDa disappeared in less than one year in the patients cured after surgery, while in patients with persistent or recurrent parasitism the bands present before surgery persisted or other new ones appeared. The WB with purified antigens proved to be highly useful in the diagnosis and post-surgical monitoring of hydatidosis patients. The antigen used is proposed as a standard antigen for the diagnosis and follow-up of pre- and postsurgical hydatidosis.

Adult↗

PubMed2001

Antigen incorporation on Cryptosporidium parvum oocyst walls.

Cryptosporidium parvum oocysts are the infective stages responsible for transmission and survival of the organism in the environment. In the present work we show that the oocyst wall, far from being a static structure, is able to incorporate antigens by a mechanism involving vesicle fusion with the wall, and the incorporation of the antigen to the outer oocyst wall. Using immunoelectron microscopy we show that the antigen recognized by a monoclonal antibody used for diagnosis of cryptosporidiosis (Merifluor(R), Meridian Diagnostic Inc.) could be found associated with vesicles in the space between the sporozoites and the oocysts wall, and incorporated to the outer oocyst wall by an unknown mechanism.

Animals↗

PubMed1997

Specific recognition of hydatid cyst antigens by serum IgG, IgE, and IgA using western blot.

Diagnosis of hydatid disease in humans relies on the detection of specific antibodies against antigens of the metacestode from Echinococcus granulosus. The specificity and sensitivity of current immunological techniques based on specific serum IgG rely on the way antigens are purified. We used Western immunoblotting to detect specific IgG, IgE, and IgA antibodies in serum from patients with hydatid disease using either crude antigen preparations (total hydatid fluid), purified fractions enriched in Antigens 5 and B, and glycoproteins from hydatid fluid. Depending on whether crude HF or purified antigen fractions were used, IgG and IgE recognized specifically low-to-medium MW bands between 12 and 42 kDa. IgA recognized specifically 110 kDa band in crude hydatid fluid and in the glycoprotein fraction of hydatid fluid, and a 42 kDa band in all antigen samples used. Besides the advantage of detecting specific IgA in crude hydatid fluid, these results offer the possibility of simplifying future immunological tests if specific secretory IgA can be similarly detected.

Adult↗

PubMed1996

Serologic recognition of hydatid cyst antigens using different purification methods.

The specificity and sensitivity of enzyme-linked immunosorbent assays (ELISA) and Western immunoblot assays in detecting antibodies in serum from patients suffering cystic hydatid disease (Echinococcus granulosus) are compared using either crude antigen preparations (total sheep hydatid fluid and homogenates of protoscoleces), purified fractions enriched in Antigens 5 and B, and glycoproteins from hydatid fluid. Polyprotein bands of 12-14, 20, and 34 kDa, when purified from hydatid fluid by applying changes in the ionic strength, yielded a sensitive (95%) immunodiagnostic test that was also extremely specific (100%) when assayed with sera from noninfected humans and from patients suffering from other parasitic diseases. However, subjecting hydatid fluid to chromatography through a concanavilin A column rendered a 42 kDa band that was sensitive (95%) as well as highly specific (100%) for hydatidosis. Therefore purification procedures can strongly affect the diagnostic value of antigens with identical electrophoretic behavior in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).

Animals↗