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Immunization of mice with stable, acapsular, yeast-like mutants of Cryptococcus neoformans
Abstract:
Immune responses, including lymphocyte transformation and protection, were evaluated in a new model of experimental murine cryptococcosis. Newly developed, genetically stable, acapsular mutants of Cryptococcus neoformans were used to immunize C3H/HeN mice. Intraperitoneal and subcutaneous routes of immunization without adjuvant were studied. Spleen cells and pooled popliteal and inguinal lymph node cells responded significantly to heat-killed, whole-cell C. neoformans antigen but not to Candida albicans antigen in lymphocyte transformation assays. No significant difference in lymphocyte transformation response to antigens was observed between intraperitoneally and subcutaneously immunized animals. Mean survival time of immunized mice was extended significantly in comparison to controls following intravenous challenge with virulent C. neoformans. Degree of protection was independent of route of immunization but dependent upon the magnitude of the challenge inoculum. This model should prove valuable in the study of immunoregulation of cryptococcosis and vaccine development.
Insights
This study introduces a new mouse model for cryptococcosis, demonstrating that immunization with acapsular Cryptococcus neoformans enhances immune responses and survival. The model is valuable for studying cryptococcosis immunity and developing vaccines.
Area of Science:
- Immunology
- Infectious Diseases
- Microbiology
Background:
- Cryptococcosis is a serious fungal infection caused by Cryptococcus neoformans.
- Developing effective vaccines and understanding immune responses are crucial for managing cryptococcosis.
Purpose of the Study:
- To evaluate immune responses and protection in a novel murine model of cryptococcosis.
- To assess the efficacy of immunization using acapsular Cryptococcus neoformans mutants.
Main Methods:
- Genetically stable, acapsular Cryptococcus neoformans mutants were used for immunization in C3H/HeN mice via intraperitoneal and subcutaneous routes.
- Lymphocyte transformation assays were performed using spleen and lymph node cells stimulated with C. neoformans antigen.
- Immunized mice were challenged intravenously with virulent C. neoformans to assess survival.
Main Results:
- Immunized mice showed significant lymphocyte transformation responses to C. neoformans antigen.
- Both immunization routes (intraperitoneal and subcutaneous) induced comparable lymphocyte responses.
- Immunization significantly extended mean survival time compared to controls.
- Protection was independent of immunization route but dependent on challenge inoculum size.
Conclusions:
- The developed murine model effectively demonstrates immune responses and protection against cryptococcosis.
- This model is a valuable tool for investigating the immunoregulation of cryptococcosis and for vaccine development efforts.