Not all vaginal microbiomes are equal: functional context shapes immune landscapes.

Area of Science:

• Microbiome research
• Reproductive health
• Computational biology

Background:

• Vaginal microbiome's role in reproductive health is crucial but poorly understood.
• 16S rRNA sequencing limits understanding of strain-level variation and functional diversity.
• Gardnerella species dominance doesn't always indicate dysbiosis.

Purpose of the Study:

• To develop a novel framework for classifying vaginal microbiome functional and ecological diversity.
• To define metagenomic subspecies and community state types (mgCSTs) beyond taxonomic classification.
• To investigate the functional and host immune implications of different vaginal microbiome structures.

Main Methods:

• Utilized the expanded VIRGO2 gene catalog.
• Developed the vaginal inference of subspecies and typing algorithm (VISTA), an ortholog-based framework.
• Applied metagenomic sequencing and scalable computational modeling.

Main Results:

• Defined metagenomic subspecies and 25 metagenomic community state types (mgCSTs).
• Identified six distinct Gardnerella-dominated profiles within the mgCSTs.
• Demonstrated significant differences in species composition, gene content, transcriptional activity, and host immune responses across mgCSTs.

Conclusions:

• Vaginal microbiome classification requires functional and ecological context, not just taxonomy.
• VISTA provides a scalable tool for studying vaginal microbiome function and host interactions.
• This framework supports functionally informed diagnostics and precision interventions for women's reproductive health.