How vaginal bacteria help to get rid of papillomavirus (HPV)
Papillomavirus (HPV) is a common infection that leads to cervical cancer in some women, but not in others, for whom the virus is cleared after a few months. This resistance may be due to certain bacteria in the vaginal microbiota.
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About this article
Cervical cancer is the fourth most common cancer in women. 99% of all cases follow infection with papillomavirus (HPV), an extremely common virus transmitted through sexual contact. Fortunately, in 80% of cases, HPV disappears spontaneously within two years of infection. However, for one in five women infection persists and may lead to cervical cancer. Why are some women unable to eliminate it? And why do some develop pre-cancerous lesions as a result of the virus? Chinese researchers have attempted to answer all these questions.
They believe the vaginal microbiota is involved. Previous studies had observed a vaginal dysbiosis in infected patients: high abundance of certain lactobacilli appears to reduce the risk of infection, whereas the lactobacillus L. iners is more frequent in infected patients. However, the studies’ findings are at times contradictory. As a result, researchers in Shanghai carried out this complementary study on 73 women infected by HPV and presenting first lesions of the cervix.
27% Only 27% of women surveyed say they know that the vaginal microbiota is balanced when its bacterial diversity is low
Two bacteria involved
Almost two out of three patients saw HPV clearance after one year, with the rest remaining infected. The persistence or otherwise of the virus was not due to differences in the patients’ age, the stage of the disease, the HPV subtype, the type of vaginal bacterial community (there are five main types, somewhat like blood groups), or vaginal microbiota diversity. On the other hand, the presence of two specific bacteria seemed to be involved: women with depleted levels of enterococcus ASV_62 in their cervix and enriched in L. iners were less likely to have cleared HPV after one year.
99% of all cervical cancer cases are linked to infection with human papillomavirus (HPV), an extremely common virus transmitted through sexual contact.
4th Cervical cancer is the fourth most common cancer in women.
604,000 In 2020, an estimated 604,000 women were diagnosed with cervical cancer worldwide and about 342,000 women died from the disease.
Sources: WHO.
Preventing cervical cancer
Will future treatments target these two bacteria (promoting one and reducing the other) to drive out HPV and prevent cervical cancer? Perhaps...if further studies support these findings. In the meantime, HPV vaccination for teenagers and regular cervical cancer screening (vaginal smears to detect precancerous lesions) for all women aged 25 to 65 is enough to prevent most cases of cervical cancer.
The vaginal microbiota
Shi W, Zhu H, Yuan L et al. Vaginal microbiota and HPV clearance: A longitudinal study. Front Oncol. 2022 Oct 24;12:955150.
