Is Cryptococcus neoformans a pleomorphic fungus?

Area of Science:

• Mycology
• Medical Mycology
• Fungal Pathogenesis

Background:

• Cryptococcus neoformans is a human fungal pathogen classically known as a budding yeast.
• Recent studies have identified novel single-cell morphologies relevant to infection in vivo and in vitro.
• The classification of these morphologies as true morphotypes is debated.

Purpose of the Study:

• To determine if newly discovered C. neoformans cell morphologies represent true morphotypes.
• To evaluate C. neoformans for characteristics of pleomorphism, a trait seen in other fungi.
• To provide a framework for classifying fungal single-cell morphologies.

Main Methods:

• Profiling of C. neoformans seed cells and titan cells.
• Transcriptional analysis of different C. neoformans cell forms.
• Assessment of morphology stability and heritability.
• Evaluation of growth characteristics associated with distinct morphologies.

Main Results:

• Multiple C. neoformans single-cell morphologies are transcriptionally distinct.
• These morphologies are stable and heritable across generations.
• The identified morphotypes are associated with active fungal growth.
• A framework was established for classifying fungal morphotypes.

Conclusions:

• C. neoformans exhibits true morphotypes, supporting its classification as a pleomorphic fungus.
• The capacity for morphotype switching is a key factor in C. neoformans pathogenesis.
• Updated classification reflects the complex biology of this important fungal pathogen.