Characteristics of Paecilomyces lilacinus infection comparing immunocompetent with immunosuppressed murine model
Related Experiment Video
Updated: Jun 1, 2026
Murine Model of Epicutaneously-Induced Immunomodulation
Published on: June 24, 2025
Marcelly Maria dos Santos Brito1, Mariana da Silva Lima, Fernanda Nazaré Morgado
1Laboratory of Taxonomy, Biochemistry and Bioprospection of Fungi, Oswaldo Cruz Instituto, Rio de Janeiro, Brazil.
Abstract:
The characteristics of Paecilomyces lilacinus infection were evaluated using two murine experimental models: immunocompetent and immunosuppressed. The evaluation criteria for characteristics of infection were clinical signs, weight loss, survival rates, histopathological alterations and the number of viable fungal cells re-isolated from different organs; and those for immunological status were in vitro lymphoproliferative response, cell surface phenotyping and IFN-γ production. Morphological evaluation showed that P. lilacinus isolates presented morphological characteristics consistent with those described in the literature. The immunocompetent mice could be infected by the fungi, but they did not develop the disease, unlike the immunosuppressed mice, which showed clinical signs of mycosis in an environment of suppressed cellular immune response. The hypothesis of latent infection reactivation in mice was not confirmed. The difference observed in the infection rate of the two fungi isolates points to an intrinsic variation between strains of P. lilacinus and led us to hypothesise that even in the presence of immunosuppressed environment, the fungus virulence can play a role in the pathogenesis of hyalohyphomycosis.
Insights
Paecilomyces lilacinus infection causes disease in immunosuppressed mice but not immunocompetent ones. Fungal strain virulence, not just immune status, influences hyalohyphomycosis development.
Area of Science:
- Mycology
- Immunology
- Pathogenesis
Background:
- Paecilomyces lilacinus is a fungus with varying pathogenic potential.
- Understanding its infection characteristics is crucial for diagnosing and treating hyalohyphomycosis.
Purpose of the Study:
- To evaluate the infection characteristics of Paecilomyces lilacinus in immunocompetent and immunosuppressed murine models.
- To investigate the role of fungal strain virulence and host immune status in disease development.
Main Methods:
- Murine models (immunocompetent and immunosuppressed) were used to study P. lilacinus infection.
- Evaluation included clinical signs, weight loss, survival, histopathology, fungal re-isolation, and immunological assays (lymphoproliferative response, cell phenotyping, IFN-γ production).
Main Results:
- Immunocompetent mice showed infection but no disease, while immunosuppressed mice developed clinical signs of mycosis.
- Latent infection reactivation was not confirmed.
- Differences in infection rates between fungal isolates suggest intrinsic strain variation and potential role of virulence.
Conclusions:
- Host immunosuppression is a critical factor for P. lilacinus to cause disease.
- Fungal strain virulence may play a significant role in the pathogenesis of hyalohyphomycosis, even in immunocompromised individuals.
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