Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item Enzyme-linked Immunosorbent Assay (ELISA) using recombinant protein antigens for detection of anti-chikungunya antibodies(Faculty of Tropical Medicine, Mahidol University, 2010) Athapaththu, A.M.M.H.; Khanna, N.; Abeyewickreme, W.; Gunasena, S.; Hapugoda, M.D.OBJECTIVES: Chikungunya is a mosquito borne viral infection that has caused great medical and public health problems in South East Asia during last few years. Currently available laboratory diagnostic kits depend on Enzyme-Linked Immunosorbent Assay (ELISA) based on whole viral antigens caused biohazard risk, high production cost and cross reactivity with other organisms of the same genus/family. These problems can be avoided by using recombinant protein antigens in ELISAs. METHODOLOGY: Two novel recombinant protein antigens based on Envelope (E) domain, a critical antigenic region of the major structural protein of chikungunya virus were expressed separately in a bacterial expression system (Escherichia coli). Two proteins were purified under denatured conditions. They were evaluated as potential diagnostic intermediates for detection of and-chikungunya antibodies in Immunoglobulin M (IgM) and Immunoglobulin G (IgG) ELISAs separately using a panel of serum samples confirmed by the gold standard assay, Heamagglutination Inhibition (HAI) assayRESULTS: These 2 protein antigens: El and E2 showed more than 60% positivity in IgG ELISAs and IgM ELISAs. A field validation using a large number of serum samples should be done for further confirmation of these results. It can be concluded that these 2 novel recombinant protein antigens can be used as a diagnostic intermediate to detect anti-chikungunya antibodies. ACKNOWLEDGEMENTS: Financial assistance from the International Centre for Genetic Engineering and Biotechnology (1CGEB CRP/ SRI08-02) is gratefully acknowledgedItem A Comparative field study of novel commercial Antigen Detection Enzyme-Linked Immunosorbent Assay (ELISA) with Reverse Transcription Polymerase Chain Reaction (RT- PCR) assay for early definitive laboratory diagnosis of dengue viral infection in Sri Lanka(Sri Lanka Association for the Advancement of Science, 2007) Hapugoda, M.D.; Jayasooriya, D.H.S.W.; Gunawardene, Y.I.N.S.; Wellawaththage, C.; Premaratna, R.; Abeyewickreme, W.Dengue is an important mosquito borne viral infection in South East Asia. Early definitive laboratory diagnosis of infection would help in management of patients and reducing the case fatality rate. The objective of this study was to determine the accuracy of novel commercial Antigen Detection Enzyme-Linked Immunosorbent Assay (ELISA) using Non Structural protein 1 (NS1) (Bio Rad) for early definitive laboratory diagnosis of dengue infection under field conditions in Sri Lanka. A panel of acute serum samples collected from 99 patients clinically suspected of having dengue fever (<5 days) warded at the North Colombo Teaching Hospital, Ragama, Sri Lanka were used for the present study. Serum samples were tested using Antigen Detection ELISA according to the method described by the manufacturer. Results of this novel assay were compared with RT-PCR assay using Chi-squared test. Two variables were analyzed at a 95% confidence interval and P value <0.05 was considered as significant. Twenty two and 65 patients were positive and negative, respectively, for dengue infection by both assays. Nine patients were confirmed as dengue by the Antigen Detection ELISA only. Three patients were confirmed as dengue by RT-PCR assay only. Antigen detection ELISA showed 88% of agreement with the RT-PCR assay. According to the Chi-squared test, there was no significant difference between the two assays for early diagnosis of dengue infection (?2=46, P=0.0000). Novel commercial Antigen Detection ELISA kit (Bio-Rad 72830) can be used for early definitive laboratory diagnosis of dengue infection in Sri Lanka under field conditions. Acknowledgement: the International Atomic Energy Agency (SRL 06/28) for technical co-operation and APCOT Marketing LTD, Sri Lanka for supplying Antigen detection ELISA kits.Item Human infection with Wuchereria bancrofti in Matara, Sri Lanka: the use, in parallel, of an ELISA to detect filaria-specific IgG4 in urine and of ICT card tests to detect filarial antigen in whole blood(Academic Press, 2003) Weerasooriya, M.V.; Itoh, M.; Mudalige, M.P.; Qiu, X.G.; Kimura, E.; Gunawardena, N.K.; Fujimaki, Y.The ICT card test to detect circulating filarial antigen and an ELISA that detects filaria-specific urinary IgG(4) were each used to screen 473 subjects from a community in Sri Lanka where Wuchereria bancrofti is endemic. When the ICT test was used as the gold standard, the ELISA was found to have a sensitivity of 91.2%. However, far more of the subjects were found ELISA-positive than ICT-positive (76.5% v. 31.1%). The youngest children studied (aged 1-10 years) were similar to the adult subjects in terms of the prevalence of antigenaemia (33.8%) and the prevalence (72.1%) and concentration of filaria-specific IgG(4) in their urine. Therefore, especially as urine samples are easier, less painful and safer to collect than blood samples, the ELISA may be particularly useful to screen very young and school-age children, to estimate current levels of transmission in a particular area.