Influence of vaginal lactobacilli on barrier properties of cervicovaginal mucus against HIV

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  • March 19, 2019
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  • Nunn, Kenetta
    • Affiliation: School of Medicine, UNC/NCSU Joint Department of Biomedical Engineering
Abstract
  • The vaginal epithelium is coated with cervicovaginal mucus (CVM), a dense mesh network of mucin fibers that HIV in semen must penetrate in order to reach target cells residing in the epithelium. Trapping HIV in CVM offers the potential to prevent initial HIV infections altogether, and likely accounts in part for the generally low rates of HIV transmission (~1 in 100-1000 coital acts). CVM is populated by a dense microbial community that can differ markedly between women as well as in the same woman over time, and epidemiological studies indicate that the microbiota can significantly impact the risk of acquiring HIV. Nevertheless, little is understood about whether specific microbes, including different species of Lactobacillus, may modulate the barrier properties of CVM against HIV. In this thesis, I decided to investigate whether differences in the vaginal microbiota may result in differential ability of native CVM to immobilize and trap HIV. Using high-resolution particle tracking, I found that HIV mobility across different CVM specimens was not correlated to vaginal pH or total lactic acid levels, and only slightly correlated to Nugent scores. Instead, I found that HIV readily penetrates CVM with low levels of D-lactic acid (D-LA), but is consistently trapped in CVM with high D-LA levels. Based on vaginal microbiome analysis using high throughput 16S rRNA gene sequencing, I confirmed that CVM specimens with low levels of native D-LA are more likely to possess a L.iners dominated microbiota, whereas CVM specimens with high levels of native D-LA are more likely to possess a L. crispatus dominated microbiota. These results indicate that vaginal Lactobacilli spp. can alter the barrier properties of CVM against HIV, and that L. iners, rather than solely BV-associated microbes, may be correlated to increased susceptibility to HIV transmission relative to L. crispatus.
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  • In Copyright
Advisor
  • Lai, Samuel
  • Button, Brian
  • Swanstrom, Ronald
Degree
  • Master of Science
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2014
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  • Chapel Hill, NC
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  • This item is restricted from public view for 1 year after publication.
Date uploaded
  • April 22, 2015

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