Microevolution during Chronic Infection May Lead T. asahii to Coexist with the Host
Gen Ba1, Xuelian Lv2, Xin Yang3
1Department of Pathology The 305 Hospital of PLA, Beijing, China.
Background:
Trichosporon asahii (T. asahii) is part of the cutaneous fungal microbiota in humans and can cause lethal opportunistic infection. During infection, microorganisms can adapt to their environment by adjusting gene expression and cellular activities.
Objectives:
Investigation of the microevolutionary changes in T. asahii during chronic infection.
Methods:
Two T. asahii strains were isolated from a chronic trichosporonosis patient between a 15-year interval, and the microevolutionary changes were compared by the immune response of dendritic cell (DC), mice survival model, and transcriptome sequencing analysis.
Results:
Compared with the primary T. asahii strain, the microevolved strain induced much lower expression of TNF-α by mice bone marrow-derived DC and had a much superior survival rate, a total of 2212 significantly differentially expressed genes were identified in the microevolved strain, and functional analysis showed significance in the downregulated transcription and metabolic process, especially the valine, leucine, and isoleucine degradation pathways, which were associated with pathogenicity and virulence; hence, the results were highly consistent with the decreased immunogenicity and virulence of the microevolved strain.
Conclusions:
These results demonstrated that the microevolution during chronic infection could induce changes in immunogenicity, virulence, and transcriptome, which might lead T. asahii to coexist with the host.
Insights
Microevolution in Trichosporon asahii during chronic infection led to decreased virulence and immunogenicity. These changes in gene expression and cellular activities may allow the fungus to coexist with the host.
Area of Science:
- Medical Mycology
- Microbial Evolution
- Immunology
Background:
- Trichosporon asahii is a human fungal commensal capable of causing life-threatening opportunistic infections.
- Fungi adapt to host environments through altered gene expression and cellular functions during infection.
Purpose of the Study:
- To investigate the microevolutionary adaptations of Trichosporon asahii during prolonged chronic infection.
Main Methods:
- Comparison of two T. asahii strains isolated 15 years apart from a patient with chronic trichosporonosis.
- Assessment of immune responses using dendritic cells (DCs) and a mouse survival model.
- Transcriptome sequencing analysis to identify gene expression differences.
Main Results:
- The evolved T. asahii strain showed reduced TNF-α expression in DCs and improved host survival rates compared to the primary strain.
- 2212 differentially expressed genes were identified in the evolved strain, with significant downregulation in transcription and metabolic processes, including amino acid degradation pathways.
- These molecular changes correlated with decreased fungal immunogenicity and virulence.
Conclusions:
- Microevolution during chronic infection significantly alters T. asahii's immunogenicity, virulence, and transcriptome.
- These adaptive changes may facilitate long-term coexistence between T. asahii and the host.
