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Immuno-fluorescence Assay of Leptospiral Surface-exposed Proteins
Published on: July 1, 2011
Five Leptospira spp. Antibody Point-of-Care Tests in Healthy Dogs Reveal Different Results After Revaccination
Katharina Gesa Schmitt1, Michèle Bergmann1, Hans van der Linden2
1LMU Small Animal Clinic, Centre for Clinical Veterinary Medicine, Faculty of Veterinary Medicine, LMU Munich, Veterinaerstrasse 13, 80539 Munich, Germany.
Abstract:
The microscopic agglutination test (MAT) is the diagnostic standard for canine leptospirosis. However, it is a time-consuming process and does not differentiate between infection- and vaccine-induced antibodies. Canine Leptospira spp.-specific antibody point-of-care (POC) tests provide the rapid detection of immunoglobulin M (IgM) and/or G (IgG). IgM POC tests are considered to become negative more rapidly after vaccination, making them more effective at diagnosing leptospirosis in not-recently vaccinated dogs. This study analysed 582 serum samples of 97 healthy dogs using five different POC tests and the MAT before vaccination and 2, 4, 12, 26, and 52 weeks afterwards. Among the POC tests, three detected IgM antibodies, one detected IgG antibodies, and one detected both IgM and IgG. The results were analysed using mixed-effects logistic regression. Before vaccination, only 2/291 IgM tests were positive (0.7%), compared to 45/194 IgG tests (23.2%). All the POC tests became positive after vaccination, but IgM positivity occurred significantly less frequently (59/1746), especially >4 weeks post-vaccination (7/59 positive results), with 94.5-99.6% specificity compared to 41.4-77.8% in IgG tests. These findings support the use of IgM POC tests in vaccinated dogs, while IgG POC tests are more difficult to interpret.
Insights
Canine leptospirosis diagnosis is improved with point-of-care (POC) tests. Immunoglobulin M (IgM) POC tests are more reliable than immunoglobulin G (IgG) tests for diagnosing leptospirosis in vaccinated dogs.
Area of Science:
- Veterinary Diagnostics
- Immunology
- Infectious Diseases
Background:
- The microscopic agglutination test (MAT) is the gold standard for diagnosing canine leptospirosis but is slow and cannot distinguish between infection and vaccination.
- Point-of-care (POC) tests offer rapid detection of antibodies, with immunoglobulin M (IgM) and immunoglobulin G (IgG) tests showing potential for differentiating vaccine responses.
Purpose of the Study:
- To evaluate the diagnostic performance of canine leptospirosis antibody point-of-care tests (POCs) in vaccinated dogs.
- To compare the utility of IgM and IgG POC tests in distinguishing between vaccine-induced and pre-existing antibodies.
Main Methods:
- Serum samples from 97 healthy dogs were tested using five different POC tests (three IgM, one IgG, one IgM/IgG) and MAT before and at multiple time points after vaccination.
- Mixed-effects logistic regression was used to analyze the specificity and positivity rates of IgM and IgG POC tests over time.
Main Results:
- Before vaccination, IgM POC tests showed low positivity (0.7%), while IgG tests showed higher positivity (23.2%).
- All POC tests became positive post-vaccination. IgM positivity decreased significantly after 4 weeks, demonstrating high specificity (94.5-99.6%).
- IgG tests exhibited lower specificity (41.4-77.8%) post-vaccination, making interpretation challenging.
Conclusions:
- IgM POC tests are valuable tools for diagnosing leptospirosis in vaccinated dogs due to their ability to return to negative levels post-vaccination.
- IgG POC tests are less reliable for diagnosing leptospirosis in vaccinated dogs due to persistent positivity and lower specificity.
