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Updated: Jun 6, 2025
Immuno-fluorescence Assay of Leptospiral Surface-exposed Proteins
Published on: July 1, 2011
Immunological characterization of recombinant outer membrane Loa22 protein of local pathogenic Leptospira serovars
Mehdi Gharakhani1, Mohammad Faezi Ghasemi1, Pejvak Khaki2
1Department of Microbiology, Faculty of Basic Sciences, Lahijan Branch, Islamic Azad University, Lahijan, Iran.
Abstract:
Leptospirosis is a worldwide zoonotic disease caused by pathogenic Leptospira spp., often occurring in tropical and subtropical regions. Focusing on development of rapid diagnostic methods to facilitate early diagnosis and a universal vaccine are the main critical issues to overcome the burden of leptospirosis. Here, we have studied the immunogenic potential of prepared recombinant Loa22 protein (rLoa22) of local pathogenic Leptospira species in mice and its ability to induce humoral and cellular immunity, being further evaluated by analyzing the immunoglobulin G (IgG) subclasses and cytokines produced through immunization. Based on the results, mice immunized with rLoa22/adjuvant and a trivalent vaccine, induced high titers of total IgG. All immunized groups increased IgG1 almost on the same level; but, IgG2a level was significantly higher in the vaccine and rLoa22/adjuvant groups than rLoa22 alone group. Animals immunized with the vaccine produced more interleukin 4 than rLoa22/ adjuvant group. The results of evaluating interferon gamma level showed that the rLoa22/adjuvant and vaccine groups had a significant increase compared to the rLoa22 alone group. The results also demonstrated that the rLoa22 protein, in indirect enzyme-linked immunosorbent assay, was able to detect the anti-Leptospira antibodies in mice serum that can be used as a marker in assessing the seroprevalence of leptospirosis and/or in combination with other leptospiral antigens in development of an effective vaccine against leptospirosis.
Insights
This study shows that the recombinant Loa22 protein (rLoa22) from Leptospira can induce a strong immune response in mice. This rLoa22 shows potential for developing new diagnostic tools and effective vaccines against leptospirosis.
Area of Science:
- Veterinary Medicine
- Immunology
- Infectious Diseases
Background:
- Leptospirosis is a global zoonotic disease caused by pathogenic Leptospira species, prevalent in tropical and subtropical areas.
- Developing rapid diagnostics and a universal vaccine are critical for controlling leptospirosis burden.
Purpose of the Study:
- To investigate the immunogenic potential of recombinant Loa22 protein (rLoa22) from local Leptospira species in mice.
- To evaluate the humoral and cellular immune responses induced by rLoa22 immunization.
- To assess rLoa22's utility in diagnostics and vaccine development.
Main Methods:
- Mice were immunized with rLoa22 alone, rLoa22 with adjuvant, or a trivalent vaccine.
- Humoral immunity was assessed by analyzing immunoglobulin G (IgG) subclasses (IgG1, IgG2a).
- Cellular immunity was evaluated by measuring cytokine production (interleukin-4, interferon-gamma).
- The ability of rLoa22 to detect anti-Leptospira antibodies was tested using indirect enzyme-linked immunosorbent assay (ELISA).
Main Results:
- Immunization with rLoa22/adjuvant and the trivalent vaccine induced high total IgG titers.
- While IgG1 levels were similar across groups, IgG2a levels were significantly higher in the vaccine and rLoa22/adjuvant groups.
- The vaccine group showed higher interleukin-4 production compared to the rLoa22/adjuvant group.
- Interferon-gamma levels significantly increased in the rLoa22/adjuvant and vaccine groups versus rLoa22 alone.
- rLoa22 successfully detected anti-Leptospira antibodies in mouse serum via ELISA.
Conclusions:
- Recombinant Loa22 protein (rLoa22) effectively elicits both humoral and cellular immune responses in mice.
- rLoa22 demonstrates potential as a diagnostic marker for seroprevalence studies.
- rLoa22 may serve as a valuable component in developing a more effective leptospirosis vaccine.
