Lactic acid in vaginal fluid inactivates HIV-1

What is it about?

Lactobacillus-dominated vaginal microbiota is associated with a reduced risk of acquiring and transmitting HIV and other sexually transmitted infections (STIs). Lactic acid is a major organic acid metabolite produced by lactobacilli that acidifies the vagina and has been reported to have inhibitory activity in vitro against bacterial, protozoan, and viral STIs, including HIV infections. However, the anti-HIV properties of lactic acid in native vaginal lumen fluids of women colonized with Lactobacillus spp. have not yet been established. Our study, using native cervicovaginal fluid from women, found that potent and irreversible anti-HIV-1 activity is significantly associated with the concentration of the protonated (acidic, uncharged) form of lactic acid.

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Why is it important?

This work shows that lactic acid present in vaginal fluids has biological activity and advances our understanding of the mechanisms by which vaginal microbiota modulate HIV susceptibility. This study could lead to non-antibiotic-dependent strategies to prevent women from acquiring HIV or transmitting the virus during vaginal intercourse and vaginal birth. This could potentially be achieved through either treatment with lactic acid producing lactobacilli (biotherapeutics) or delivery of intravaginal lactic acid in women who have vaginal microbiota depleted of beneficial lactobacillli although this equires further investigation in human studies.

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