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Published on: July 26, 2019
Antigenic diversity of Encephalitozoon hellem demonstrated by subspecies-specific monoclonal antibodies
1Unité des Rickettsies, CNRS UPRES-A 6020, IFR 48, Faculté de Médecine, Marseille, France.
Abstract:
Encephalitozoon hellem is a unicellular, obligate intracellular microsporidian species detected and isolated in HIV-infected patients presenting with keratoconjunctivitis, sinusitis, tracheobronchitis, nephritis, cystitis, and disseminated infection. A total of 24 monoclonal antibodies were produced against E. hellem and characterized. The monoclonal antibodies were of the immunoglobulin (Ig) G and Ig M subclasses, and, when incorporated into indirect immunofluorescence and immunoblotting assays, reacted against 13 isolates of E. hellem originating from three geographic regions. These monoclonal antibodies did not react with one strain each of either Encephalitozoon intestinalis or Encephalitozoon cuniculi, demonstrating their specificity. Two monoclonal antibodies reacted with all karyotype B-E. hellem isolates but did not react with karyotype A-isolates from North America and the Netherlands, thus demonstrating antigenic diversity among E. hellem isolates. These results add to the increasing evidence for diversity among E. hellem, which therefore may be reclassified into subspecies.
Insights
Monoclonal antibodies revealed genetic diversity within Encephalitozoon hellem, a microsporidian pathogen affecting HIV patients. This discovery suggests Encephalitozoon hellem may require reclassification into subspecies due to distinct antigenic profiles.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Encephalitozoon hellem is an opportunistic microsporidian pathogen frequently identified in HIV-infected individuals.
- This pathogen causes various infections, including keratoconjunctivitis, sinusitis, and disseminated disease.
Purpose of the Study:
- To produce and characterize monoclonal antibodies against Encephalitozoon hellem.
- To assess the specificity of these antibodies against other Encephalitozoon species.
- To investigate antigenic diversity among different isolates of Encephalitozoon hellem.
Main Methods:
- Production of 24 monoclonal antibodies against Encephalitozoon hellem.
- Characterization of antibody subclasses (IgG, IgM).
- Application of indirect immunofluorescence and immunoblotting assays for reactivity testing against 13 E. hellem isolates, E. intestinalis, and E. cuniculi.
Main Results:
- Monoclonal antibodies demonstrated high specificity, reacting only with E. hellem and not with E. intestinalis or E. cuniculi.
- Two specific monoclonal antibodies distinguished between karyotype B and karyotype A isolates of E. hellem.
- Reactivity patterns indicated significant antigenic diversity among E. hellem isolates from different geographic origins.
Conclusions:
- The developed monoclonal antibodies are valuable tools for specific detection and differentiation of Encephalitozoon hellem.
- Antigenic diversity observed among E. hellem isolates supports the potential need for reclassification into subspecies.
- Further research into E. hellem diversity may impact diagnostic and therapeutic strategies for microsporidian infections.
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