Browsing by Author "Manamperi, A.A.P.S."

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A Double antibody sandwich ELISA for the diagnosis of vivax malaria: a tool for further research
(University of Colombo, 2000) Seneviratna, G.D.C.N.; Manamperi, A.A.P.S.; Kapilananda, G.M.G.; Longacre, S.; Handunnetti, S.M.; Udagama-Randeniya, P.V.
A diagnostic assay for Plasmodium vivax based on a double antibody sandwich enzyme-linked immunosorbent assay (DAS ELISA) was established to detect the merozoite surface protein 1 (PvMSP1) in wild isolates. This assay was based on the recombinant protein p19, a C-terminal processing product of PvMSP1. Of the two anti-P. vivax monoclonal antibodies (MAbs) selected, A21 was used as the capture antibody while horse radish peroxidase labelled A8 served as the probing second antibody. Optimized conditions established for p19 based DAS ELISA with the exception of a lower concentration of Tween-20 in buffers were suitable to screen lysed whole blood of malaria patients. This assay had a specificity of 100 percent for P. vivax and all the isolates of P. falciparum tested negative. Of the P. vivax-infected blood samples, only those containing both compact and schizont stages were diagnosed positive. The rest of the isolates tested negative either due to stage specificity of this assay or to the antigenic diversity of PvMSP1 in wild isolates. This test demonstrated a sensitivity of 27.58 percent and an accuracy of 63.15 percent. The positive and negative predicted values of this ELISA were 100 percent and 57.14 percent, respectively. Therefore, the P. vivax specific DAS ELISA developed and tested in the present study is not sufficiently sensitive to be used as a diagnostic tool for vivax malaria. Nevertheless, a baseline was established for development of diagnostic ELISA for future use with a more appropriate antigen.
Micro mapping of common alpha thalassaemia deletions (3.7 kb, 4.2 kb) in Sri Lanka and assessment of the contribution of alpha thalassemia to hypochromic microcytosis
(Sri Lanka Medical Association, 2014) Rodriao, B.K.R.P.; Perera, H.L.; Branava, U.; Manamperi, A.A.P.S.; Weatherall, D.J.; Premawardhena, A.P.
INTRODUCTION AND OBJECTIVES: The exact prevalence and distribution of a thalassaemia in Sri-Lanka is not known, and it is widely believed that single gene deletion of a thalassaemia does not cause hypochromic rnicrocytic anaemia. To micro map the distribution of the common athalassaemia deletions in Sri Lanka and to assess its contribution to hypochromic microcytosis in the community. METHODS: A national survey on haemoglobin disorders was carried out between 2009-2010 covering all 25 districts where 300 school children of each district were screened for haemoglobin disorders and anaemia. As part of the survey 3.7 kb and 4.2 kb common alpha plus deletions were analysed using polymerase chain reaction (PCR) Gap PCR in two groups. Group 01,,2038 subjects with hypochromTc rnicrocytic anaemia [MCV < 80 fl; MCH < 27 pg], Group 02, 1305 subjects with normal MCV and MCH. RESULTS: Overall prevalence of a thalassaemia in Sri-Lanka was 9.49 % of which 3.7kb was the commonest deletion (8.27%) whilst the 4.2kb deletion accounted for 1.14%. The distribution of a thalassaemia showed remarkable variabiiity within the districts in Sri Lanka ranging from (16.33%) in Kurunegala to (3.86%) in Galie. Contrary to the present belief a thalassaemia due to single gene deletions is most often associated with hypochromic microcytic anaemia (95%) than not (5%).
Molecular evidence of hantavirus infection among clinically suspected patients with hae-morrhagic fever with renal syndrome (HFRS)
(Sri Lanka College of Microbiologists, 2013) Muthugala, M.A.R.V.; Manamperi, A.A.P.S.; Gunasena, S.; Hapugoda, M.D.; Butch, G.
INTRODUCTION: Hantavirus disease is an emerging zoonotic viral infection with high fatality. Transmission is by inhalation of aerosols generated from virus contaminated rodent excreta. There are two major clinical forms, haemorraghic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). Clinical features of HFRS, often mimic leptospirosis. Large number of cases of leptospirosis like illness has been reported in Sri Lanka annually. Although there were serological evidence of different types of hantavirus infection in Sri Lanka, diagnosis of hantavirus is not routinely performed. Due to the genetic and antigenic diversity, an assay that could detect a wide range of hantaviruses need to be established. OBJECTIVES: To establish, evaluate and validate a genus specific hantavirus RT-PCR assay. To diagnose hantavirus infection among clinically suspected HFRS patients in three selected hospitals.To describe clinical manifestations of hantavirus infections in the study population. METHODOLOGY: Genus specific conventional RT-PCR assay was established using panhanta primers and evaluated, optimized and validated using synthetic genes of 12 known hantavirus species as reference samples. Assay was able to detect a wide range of hantaviruses at minimum detection limit of 70 copies/ reaction. Molecular diagnosis of hantavirus infection was carried out in three hospitals in Colombo and Gampaha districts. Study was conducted from 01st of January 2011 to 31st of April 2011 and 61 adult patients were recruited to this study. Hantavirus RT-PCR was performed on all collected samples after extraction of RNA by TRIzol® method. RESULTS: Of 61 tested samples, 05 were positive for hantavirus genome. These results were confirmed at reference laboratory as well and species identification result is pending. Of 58 tested samples, 06 samples were positive for hantavirus IgM by in-house ELISA. All PCR positive samples were positive for hanta virus IgM. All patients with hantavirus infection had clinical and biochemical features of liver involvement in addition to fever, thrombocytopenia and renal involvement. CONCLUSION: Established RT-PCR assay was able to detect a wide range of hantaviruses and by using it molecular evidence of hantavirus infection was demonstrated in humans in Sri Lanka. Further studies are required to describe the disease epidemiology and to identify natural hosts in the country.