Leptospiral Proteins Induced In-Vivo And Its Application In The Development Of Antibody And Antigen Detection Tests For Acute Leptospirosis

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Date
2018-05
Authors
Chang, Chiat Han
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Publisher
Universiti Sains Malaysia
Abstract
Leptospirosis, caused by pathogenic Leptospira spp., is a re-emerging global health threat. Therefore, it is pertinent to identify novel diagnostic marker and investigate its potential use in antibody and antigen detection assays for detection of acute leptospirosis. Using panels of serum samples from acute (Group I) and mixed (Group II) phase leptospirosis, the present study was initiated by evaluating performance of two leptospirosis rapid diagnostic kits, namely Leptorapide and VISITECT-LEPTO, that were commonly used in Malaysia. Both test kits showed low diagnostic sensitivity (≤34%) with the acute phase serum samples, but better sensitivity with the mixed phase samples. Selected serum samples from Group I were used to identify novel diagnostic marker(s) from Leptospira genomic DNA expression library using In-vivo Induced Antigen Technology. A phage clone, S8A1, was identified and its gene fragment (named as LepS8A1FL) was cloned into recombinant plasmids. The protein was then expressed in Escherichia coli protein expression system and purified using Immobilized Metal Affinity Chromatography. Two truncated derivatives of the LepS8A1FL (namely LepS8A124 and LepS8A134) and previously reported diagnostic markers for leptospirosis (namely LigA, LipL41, OmpL1 and LipL32) were produced with the methods described above. In Immunoglobulin M (IgM) western blot, LepS8A1FL showed a satisfactory performance with 75.0% sensitivity and specificity. It outperformed the reported LipL41 and LigA in detecting acute leptospirosis. In an IgM Enzyme-Linked Immunosorbent Assay (ELISA) format, the protein, however, has moderate diagnostic value.
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Keywords
Leptospirosis, caused by pathogenic Leptospira spp , re-emerging global health threat
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