Related Experiment Video
Updated: Jul 30, 2025
Immuno-fluorescence Assay of Leptospiral Surface-exposed Proteins
Published on: July 1, 2011
Leptospira interrogans insoluble fraction as a potential antigen source for lateral flow immunochromatography
Hevandro de Souza Campos1,2, Edimilson Domingos da Silva3, Gerson Silva de Lima3
1Universidade Federal Fluminense, Departamento de Biologia Celular e Molecular, Niterói, RJ, Brasil.
Insights
The insoluble fraction of Leptospira interrogans shows promise for diagnosing leptospirosis. This antigen source offers high sensitivity and specificity in rapid diagnostic tests.
Area of Science:
- Microbiology
- Immunology
- Diagnostic Development
Background:
- Leptospirosis is an increasing zoonotic disease affecting both humans and animals.
- Current immunochromatography rapid tests for leptospirosis lack optimal sensitivity and specificity.
Purpose of the Study:
- To investigate the potential of Leptospira interrogans insoluble fraction as an antigen source for lateral flow immunochromatography (LFI).
Main Methods:
- Obtained insoluble bacterial fraction via serial centrifugation.
- Analyzed polypeptide profile using SDS-PAGE.
- Assessed immune reactivity using Western Blotting and LFI with patient sera.
Main Results:
- Predominance of low molecular mass polypeptides (2-37 kDa) with antibody reactivity between 10-38 kDa.
- LFI demonstrated 97% sensitivity and 100% specificity using MAT-positive and negative sera, respectively.
- Minimal cross-reactivity (2%) was observed.
Conclusions:
- The insoluble fraction of Leptospira interrogans is a promising antigen for developing point-of-care diagnostic tests for leptospirosis.
- This antigen source can significantly improve the accuracy of rapid leptospirosis diagnostics.
Background:
Leptospirosis is an emerging zoonosis that affects humans and animals. Immunochromatography rapid test is widely used for early diagnosis of leptospirosis, but with low sensitivity and specificity.
Objectives:
To evaluate Leptospira interrogans insoluble fraction as a potential antigen source for lateral flow immunochromatography.
Methods:
Insoluble fraction derived from the crude bacterial extract was obtained by serial centrifugation. The polypeptide profile was determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Immune reactivity of this fraction was assessed by Western Blotting and lateral flow immunochromatography (LFI). It was tested 160 microagglutination test (MAT)-positive sera from patients in the acute phase, 100 MAT-negative sera from patients with acute febrile illness, and 45 patients with other infectious diseases.
Findings:
There was a predominance of low molecular mass-polypeptide bands, ranging from 2 to 37 kDa. The antibody reactivity of theses polypeptides was found to range from 13-50%, especially between 10 and 38 kDa. Among MAT-positive sera of patients with leptospirosis in the acute phase, 97% were also positive in LFI, indicating high sensitivity. Among MAT-negative sera, all were negative in LFI, indicating high specificity. Only 2% of cross-reactivity was detected.
Conclusion:
The insoluble fraction can be a valuable antigen source for development of point-of-care diagnosis test for leptospirosis.
