# TransBiota: Genital microbiome, inflammation and HIV risk in trans men and women

> **NIH NIH R21** · UNIVERSITY OF MARYLAND BALTIMORE · 2022 · $224,775

## Abstract

SUMMARY
Transgender (trans) individuals are those who have a gender identity that does not match their birth-assigned
sex. About 1.4 million adults in the United States identified as transgender in 2016. Trans people may choose to
medically transition through gender-affirming hormones or surgeries. Trans people are at higher risk for HIV and
other sexually transmitted infections (STI), but little is known of the effect of gender-affirming medical care on
the genital microenvironment, including the microbiome and local immunology, which contribute to HIV and STI
risk in cisgender individuals. The NIH has thus identified a major need for innovative research characterizing the
biological and immunological impact of interventions used for gender reassignment. About ¼ of trans women
(assigned male at birth but with a female gender identity) have undergone vaginoplasty (surgical creation of a
neovagina, typically using penile and scrotal skin), and while these women frequently present with neovaginal
dysbiosis, little is known about the underlying pathophysiology. The penile and vaginal microenvironment in cis
men and women is a critical determinant of HIV and STI risk, yet our understanding of the composition and role
of microbiota colonizing the neovagina is scarce and completely lacking for immune outcomes. In trans men,
vaginectomy is rare (<2%) but an estimated 69% use gender-affirming testosterone therapy. Masculinizing
hormone therapy has significant effects on the vaginal epithelium that result in reduced cellular proliferation and
glycogen production. This is similar to vaginal atrophy observed during menopause in cis women, which affects
the vaginal microbiota and has negative impacts on sexual health and quality of life. Little information is available
on the relationship between vaginal microbiota and inflammation and the development of vaginal atrophy and
HIV and STI risk in trans men. Given these unknowns, the short-term goals of this research are to describe the
neovaginal and vaginal microbiomes in trans women and men, define microbes associated with local
inflammation, and then test for associations between the genital microenvironment and medicines, genital
exposures, and hormone therapy, to guide the development of novel interventions, and clinical and behavioral
best-practices, which currently are lacking. We will achieve these goals by performing a thorough and rigorous
longitudinal description of the vaginal and neovaginal microbiomes in trans men and women (Aim 1) and then
defining the relationship between these microbiomes and the genital immunology, a determining factor of HIV
and STI risk in cis individuals (Aim 2). Our study, TransBiota, will leverage a piloted and validated IRB-approved
innovative home-based sampling strategy and an innovative statistical strategy that affords scientific rigor by
correcting for experimental errors associated with microbiome analyses. Understanding the genital
microenvironment and its role in...

## Key facts

- **NIH application ID:** 10402981
- **Project number:** 1R21AI157912-01A1
- **Recipient organization:** UNIVERSITY OF MARYLAND BALTIMORE
- **Principal Investigator:** Jessica Lynn Prodger
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $224,775
- **Award type:** 1
- **Project period:** 2022-04-22 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10402981

## Citation

> US National Institutes of Health, RePORTER application 10402981, TransBiota: Genital microbiome, inflammation and HIV risk in trans men and women (1R21AI157912-01A1). Retrieved via AI Analytics 2026-05-28 from https://api.ai-analytics.org/grant/nih/10402981. Licensed CC0.

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