11 January 2017

Healthy microflora protects against HIV

The risk of HIV infection depends on the composition of the vaginal microbiota

Anna Stavina, XX2 century

Certain types of bacteria living in the vagina can affect a woman's risk of contracting HIV sexually. This conclusion was reached by researchers who worked with young healthy women in South Africa. It turned out that African women whose vaginal microbiota is dominated by pro-inflammatory bacteria are 4 times more susceptible to HIV infection than women with "normal" vaginal microflora. At the same time, the presence of viruses in the genital tract did not correlate in any way with the risk of HIV infection.

The results of the study were published on January 10 in the publication Immunity (Gosmann et al., Lactobacillus-Deficient Cervicovaginal Bacterial Communities Are Associated with Increased HIV Acquisition in Young South African).

The composition of the vaginal microbiota, which increases the risk of HIV infection, was quite widespread among the study participants. An increase in the number of CD4+ T lymphocytes, the cells that are the main target of HIV, was also recorded in their genital tract. In addition, the researchers found that when introducing samples of "high-risk" microflora to experimental mice, the number of CD4+ T-lymphocytes also increased in the mucous membrane of the animals' vagina. Scientists have suggested that the conditions created by this type of microbiota help the virus to settle in the body. Now the researchers plan to find out whether therapy with prebiotics or probiotics can reduce the risk of infection of women living in a disadvantaged environment.

"We used modern molecular methods to determine which bacteria are associated with an increased likelihood of HIV infection among young women living south of the Sahara Desert, in a region where the virus is widespread," says first author Christina Gosmann, a researcher at the Ragon Institute. – The results of our work can be directly used in practical medicine. Having identified the types of bacteria and bacterial communities associated with an increased risk of HIV infection, we have outlined goals that can be used to develop new prevention strategies and improve existing ones."

The study involved about 900 residents of the province of Kwazulu-Natal, South Africa, aged 18 to 23 years. This region is characterized by the highest rates of HIV infection in all of Africa. The volunteers visited the researchers twice a week, simultaneously taking part in the anti-poverty program. The program included classes on professional skills training, information support on HIV prevention, as well as access to condoms and a drug for pre-contact HIV prevention (we have already written about the attempts of the leadership of the District of Columbia (USA) motivate black women to use Truvada, the only drug with proven effectiveness in preventing infection with the immunodeficiency virus).

"We think of the "healthy" microbiota of the vagina as a community dominated by lactobacilli, we were taught this in medical institutes," says the lead author of the study and head of the laboratory that organized the work, Douglas Kwon. – But the studies, as a result of which we came to such a definition of normal vaginal microflora, were conducted mainly in developed countries. When we first started working in South Africa, we found that less than 10% of women here have a "healthy" microbiota in the traditional sense of the word. In most of the participants of our studies, the vaginal microflora differs in species diversity, and lactobacilli are present in it in relatively small quantities. We have shown that this type of microflora is associated not only with increased activity of inflammatory processes in the genitals, but also with an increased risk of HIV infection."


As part of the work, a new mechanism was discovered, theoretically capable of reducing inflammation in the vagina and reducing the likelihood of HIV infection. To do this, it is necessary that lactobacilli begin to predominate in women with a mixed composition of microflora in the vagina. However, it is not very easy to achieve this. Antibiotics reduce the total number of bacteria, but they do not significantly change the ratio of the number of different types of microorganisms that make up the microbiota. In addition, from studies of the intestinal microbiota, we know that the composition of the microflora returns to its original values quite quickly, even after serious changes. Therefore, additional studies will be required to create a reliable way to correct the composition of the vaginal microflora.

Portal "Eternal youth" http://vechnayamolodost.ru  11.01.2017

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