Novel Fitc-Labeled Igy Antibody: Fluorescence Imaging Toxoplasma Gondii In Vitro

Imaging Leishmania major Antigens in Experimentally Infected Macrophages and Dermal Scrapings from Cutaneous Leishmaniasis Lesions in Tunisia

Leishmania major cutaneous leishmaniasis (CL) lesions are characterized by an intense process of parasite destruction and antigen processing that could limit microscopic amastigote detection. The aim of our study was to develop a direct immunofluorescence (DIF) assay for in situ visualization of L. major antigens and access its reliability in the routine diagnosis of CL. The developed DIF assay used IgG polyclonal antibodies produced in rabbits by intravenous injections of live L. major metacyclic promastigotes chemically coupled to fluorescein isothiocyanate. Applied to L. major infected RAW macrophages, corresponding macrophage-derived amastigotes and dermal scrapings from CL lesions, the immunofluorescence assay stained specifically Leishmania amastigotes and showed a diffuse Leishmania antigen deposit into cytoplasm of phagocytic cells. Reliability of DIF in CL diagnosis was assessed on 101 methanol-fixed dermal smears from 59 positive and 42 negative CL lesions diagnosed by direct microscopy and/or kDNA real-time PCR. Sensitivity and specificity of DIF was 98.3% and 100%, respectively, being more sensitive than microscopy (p < 0.001) and as sensitive as ITS1-PCR. ITS1-PCR-RFLP allowed Leishmania species identification in 56 out of the 58 DIF-positive smears, identifying 52 L. major, two L. infantum and two L. tropica cases, which indicates antigenic cross-reactivity between Leishmania species.

Sensitive protein detection and visualization using protein-binding peptides

Silk sericin (SS) as a silk protein has important applications in biomedical and textile fields, and thus finding a facile method for detecting and imaging it is very important. Here, we show that a free SS-binding peptide, labeled with horseradish peroxidase and fluorescein isothiocyanate, could be used as a probe to determine the concentration of SS (from 1 to 100 μg/ml) in a dilute solution with a detection limit of 0.073 μg/ml and visualize the distribution of SS on a substrate under a fluorescent microscope, respectively. This work highlights the importance in discovering a protein-binding peptide and the power of such a peptide for the detection and imaging of technologically important proteins.

Conjugation and Characterization of Latex Particles with Toxoplasma gondii-specific Immunoglobulin Y Antibodies for Diagnostic Aim and Evaluation Efficiency in In Vitro Culture

Toxoplasma gondii is a parasite that causes severe health problems in the world. Toxoplasmosis, an infection caused by T. gondii, leads to high risk of mortality in patients with immunodeficiency, transplantation, and cancer. Besides that, it causes miscarriages in pregnancy, various abnormalities such as hydrocephalus in infants and congenital diseases. Because the clinical indication of the disease is not specific, it is confused with many diseases, and this leads to the necessity of directly detecting the presence of the toxoplasmosis. Therefore, various diagnostic assays are needed for the diagnosis of the disease. Amongs them, latex agglutination assay is widely used for the detection of specific antibodies or antigens in samples. Latex particles are coated with immunogenic molecules (antigens) to detect antibodies in the blood or used to identify antigens when coated with specific antibodies. In both, aggregation of latex particles results in agglutination. Monoclonal antibodies are often used in latex agglutination assay as in other diagnostic methods. However, monoclonal antibodies can be produced in low quantities at a high cost. Besides, to produce monoclonal antibodies, an experienced staff, a well-equipped cell culture laboratory, a long period of time, and a burdened budget are needed. In recent years, as an alternative to monoclonal antibodies, immunoglobulin Y (IgY) antibodies, which are obtained from chicken eggs, and specifically produced against desired antigenic constructs, have become quite attractive in terms of both low cost and abundant production without requiring infrastructure. In contrast, the latex assay based on IgY antibodies for use in the diagnosis of T. gondii has not been developed. This study aimed to conjugate T. gondii-specific IgY antibodies to latex particles, characterize the particles by Fourier transform infrared spectroscopy, scanning electron microscopy, and spectroscopic methods, and finally demonstrate the interaction with T.gondii parasites in culture with scanning electron microscopy analysis.

The Spectrophotometric Characteristic of Immunoglobulin Conjugates for Diagnostics of Causative Agents of Especially Dangerous Infections

The possibility of characterizing fluorescent immunoglobulins using spectrophotometric analysis as a testing method is considered. The comparative analysis of optical properties of fluorescent immunoglobulin preparations and their components-immunoglobulins and fluorochrome-is carried out. The obtained results testify that the proposed methodological approach of optical detection of labeled immunoglobulin molecules can be promising for tests on obtaining conjugates used in immunological tests on revealing specific antigens of causative agents of especially dangerous infections.

Enhancing the detection of Toxoplasma gondii via an anti-SAG1 scFv-alkaline phosphatase immunoconjugate

The purpose of this study was to implement a fluorometric method for enhancing the detection sensitivity of Toxoplasma gondii in biological fluids. To address this challenge, we designed and produced a recombinant immunoconjugate tool based on a single-chain antibody fragment anti-T. gondii SAG1 antigen (scFvSG15) genetically fused to the bacterial alkaline phosphatase (AP) using 4-methyl-umbelliferyl-phosphate as fluorogenic substrate. The anti-SAG1 scFv-AP conjugate was fully bifunctional and was used successfully in different assays including immunoblot, fluorometric ELISA and direct immunofluorescence. The fluorometric immunoassay afforded an extremely low detection limit (1 tachyzoite/well), which was in agreement with the real-time PCR control test. The immunofluorescence imaging has provided captivating visual evidence of T. gondii detection. These results strongly suggest that the recombinant anti-SAG1-AP conjugate generated here might serve as useful and highly sensitive immunoassay probe to direct detect T. gondii in a one-step procedure, opening up new perspectives for diagnosis of toxoplasmosis.

Egg yolk antibodies (IgY) and their applications in human and veterinary health: A review

Egg yolk constitutes a relevant alternative source of antibodies. It presents some advantages over mammalian serum immunoglobulins regarding productivity, animal welfare and specificity. The main immunoglobulin present in avian blood (IgY) is transmitted to their offspring and accumulates in egg yolks, which enables the non-invasive harvesting of high amounts of antibodies. Moreover, due to structural differences and phylogenetic distance, IgY is more suitable for diagnostic purposes than mammalian antibodies, since it does not react with certain components of the human immune system and displays greater avidity for mammalian conserved proteins. IgY has been extensively used in health researches, as both therapeutic and diagnostic tool. This article aims to review its applications in both human and veterinary health.

Chicken egg yolk antibody (IgY) as diagnostics and therapeutics in parasitic infections - A review

Early diagnosis and treatment of parasitic diseases are indispensable to combat parasites mediated morbidity and mortality in humans and animals. Mammalian sourced antibodies are being successfully used in immunotherapy and immunoassays. However, their increased conservation amongst mammals, involves them in unnecessary interaction and immune mediated pathologies, obstructing their applications in certain approaches in immunoassays. Further, the high production cost and difficulty to achieve high and stable antibody titer hampers their utility for therapeutic purposes. In recent years, chicken egg yolk immunoglobulin, termed as immunoglobulin Y (IgY) has attracted noticeable consideration since it poses greater advantages than mammalian IgG including high yield, low cost and convenience. IgY has unique properties which are being exploited in different aspects for its applications in research, diagnosis and therapy. This review gives an overview of the research outcomes pertaining to chicken IgY as diagnostics and therapeutics in parasitology.