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Aug 2021 DOI 10.14302/issn.2326-0793.jpgr-21-3917
Tarassishin LeonidCorresponding author
Department of Pathology, Albert Einstein College of Medicine, United States.
50 years ago the Enzyme Immunoassay Enzyme-Linked Immunosorbent Assay, mostly known as ELISA was developed. This is a powerful but simple method that is very widely used in the diagnostic practice, as well as in biomedical research. During this time a number of ELISA modification were developed that significantly increased its properties, especially the senstivity, such as avidin-biotin assay, immuno-PCR, nano-ELISA and finally, the digital ELISA. This short review describes the principles of ELISA and the evolution from a conventional assay to the modern ultra-sensitive method. Most of the immunological methods have two components: antigen and antibody. The high specificity of their interaction gives a possibility to detect one of them if other one is included in the reaction as a specific partner. The simplest method for antigen detection in the presence of the antibody is immune diffusion (radial immune diffusion in that case), which practically the formation of precipitate of the “antigen-antibody” complex, when the target antigen diffuses from well into agarose containing the specific antibody. Unfortunately, this assay, as well as other traditional methods, like hemagglutination or complement fixation, have a low sensitivity and are unwieldy.
Oct 2020 DOI 10.14302/issn.2576-6694.jbbs-20-3517
S.U. DOSSOU CamilleCorresponding author
Laboratoire de Recherche en Biologie Appliquée, Ecole Polytechnique d’Abomey-Calavi (EPAC), University of Abomey-Calavi, 01 BP 2009 Cotonou, Benin.
Background of the Study African countries are facing frequent blackout. Thus in sub Saharan region, due to frequent power cut, the laboratory professionals find sometimes difficulty to carry out earlier diverse diagnostic tests. Objective The aim of this work is to evaluate the feasibility of enzyme immunoassay tests in the absence of a conventional source of electricity. Methods We developed a battery-powered experimental device, which was then applied to diagnose measles. The samples included 45 sera randomly selected from non-haemolysed serum samples received and stored at the National Public Health Laboratory of Benin. The experimental device is composed of two devices (Devices 1 and 2). The Device 1 provided an average temperature of 34.47 °C, 20 min after starting. With Device 2 an average temperature of 20.32 °C is obtained 15 min after starting. Results With the experimental device the same rate of measles antibody-positive sera (44.68%) was obtained as recorded from the test using the standard equipment of laboratory. The experimental device detected 18 negative and 8 intermediate results against respectively 19 and 7 by the standard equipment. The analysis of the results of both equipments shows a concordance rate of 93.33% with a kappa reproducibility coefficient of 0.89. Conclusion The device conceived in our study is a simply equipment allowing the realization of the enzyme immunoassay tests, in this case the ELISA anti-measles test. The rate of concordance obtained shows that this device can be used with commercial kits and at temperatures close to those recommended by the manufacturer without altering the results.
Jan 2020 DOI 10.14302/issn.2372-6601.jhor-20-3186
Mamadou Sekongo YassonguiCorresponding author
Department of Training and Research, National Blood Transfusion Center; Abidjan; Côte D’Ivoire
Introduction The anti-HCV RIBA test verifies the presence of anti-HCV serum antibodies detected by the Elisa test. In Côte d'Ivoire, screening for hepatitis C is done exclusively by enzyme immunoassays. In order to reduce the number of HCV positive blood donor exclusions on ELISA, we conducted this study which aimed to demonstrate the value of the RIBA test in confirming diagnosis of viral hepatitis C to blood donors. Methods Our study, which took place from 02 to 23 February 2008 in the laboratory of Abidjan NBTC, focused on 200 sera of blood donors anti-HCV positive (Elisa test) selected according to the ratio. The DECISCAN HCV PLUS confirmation test of BIORAD was used. Results Among the 200 HCV samples positive by EIA, 49% (98/200) were confirmed positive. RIBA gave an indeterminate result in 40% of cases (80/200); and negative in 11% of cases (22/200) corresponding to false ELISA devices. In RIBA 96 samples had a low ELISA ratio of which 21% (20/96) were RIBA negative, and 79% (76/96) were indeterminate. RIBA positive samples (98/200) had a high ratio in 82% of cases (80/98). The presence of NS3 (C33) and NS4 (C100) was noted in 100% of cases (98/98, C2 in 37% (36/98) of cases and C1 in 18% of cases (18/98). RIBA indeterminate noted the presence of NS3 in 98% of cases (78/80) and NS4 in 30% of cases (24/80). Proteins C1, C2 and NS4 are essential for the diagnosis of confirmation of viral hepatitis C by RIBA. Conclusion These results attest to the lower specificity of enzyme immunoassays (ELISAs); hence the benefit of using RIBA confirmatory tests. A significant number of donors are excluded from blood donation in Côte d'Ivoire on the basis of false positive results obtained by the ELISA technique.