Health In Focus
  • Specific bacteria present in the vagina may play a role in sexual transmission of HIV, finds a study from Ragon Institute.
  • A diverse group of vaginal bacteria increases vaginal inflammation and four-fold risk of HIV infection.
  • Altering the vaginal microbiome could aid in lowering vaginal inflammation and risk of HIV infection.

HIV is one of the most dreaded diseases and there are ongoing research projects that are aimed at identifying possible mechanisms involved in the spread of the disease. A new study by a research team from Ragon Institute has identified that a specific bacteria that are found in the vagina play a role in the sexual transmission of the virus. The role of these bacteria in HIV transmission has, for so long, been unrecognized.

The study was conducted on South African women who were young, healthy and working. The findings of the study showed that women with a large amount of a particular bacterial species in their vagina had a four-fold increase in the risk of acquiring HIV when compared with women who did not have healthy vaginal bacteria.
Certain Vaginal Bacteria Found to Increase Risk of HIV Infection
Certain Vaginal Bacteria Found to Increase Risk of HIV Infection

The study that appeared in the journal Immunity and it found no correlation between viruses present in the vaginal tract and risk of HIV infection.

The micro-organisms that are normally found in humans are found to influence human development, nutrition, immunity and physiology. A mutualistic relationship exists between this microbiota and their human host, where both humans and the microbiota benefit. There are a few, however, which are opportunistic pathogens and lead to the development of serious illnesses.

High Risk Bacteria

Among the population of women who were studied, it was found that
  • High-risk bacteria was found among certain women
  • Such women with high risk bacterial population had a large number of CD4+T cells. These T cells were the target for HIV
  • Introduction of pro-inflammatory species of bacteria intra-vaginally increased the number of mucosal CD4+T cells in mouse studies.
These findings suggest that certain bacteria found in the vagina could increase the risk of HIV infection by providing a foothold for the virus to hold onto. This brings to the importance of vaginal microbiota and its far reaching effects on health and disease.

Probiotic Microorganisms

The research team are now focusing on introducing probiotic bacteria which will limit the growth and multiplication of the bacteria that have been implicated in the spread of HIV infection. The probiotic microorganisms can be introduced in women from vulnerable communities as a line of defense.

Dr.Christina Gosmann who is a postdoctoral research fellow at the Ragon Institute said that modern molecular approaches were used to characterize microbiome of the vagina and to identify specific bacteria and the HIV infection among women who lived in the sub-Saharan Africa. This is the region where HIV was found to be most profound. The author further added that the findings from the study could be applied directly to improve HIV prevention

Vaginal Microbiome

The study included over 900 women between the ages of 18-23 from the KwaZulu province of Durban in South Africa. These women took part in the Females Rising Through Education, Support and Health(FRESH) study.

The region is well known for its high HIV numbers. This region was visited by volunteers, atleast twice a week and people were enrolled in a poverty annihilation project, that provided job opportunities, job skills training as well as HIV prevention education programs.

The research team which included senior author Dr. Douglas Kwon who is a physician scientist at the Ragon Institute said that they were drawn to the region as it has a high prevalence of HIV infection. Previous studies have shown that Chlamydia could lead to inflammation in the vagina but the scientists believed that it could not account for all the incidences of HIV. Based on a previous study conducted by the same research team, it was suggested that there were certain bacterial species that aided in the attachment, growth and differentiation of HIV.

Diverse Genital Microbiome

Studies on vaginal microbiome have previously stated that they were dominant in Lactobacillus species. However, these studies have been largely associated with white women. This current study showed that the vaginal microbiome contained only 10% of Lactobacillus and that the presence of certain bacteria contributed to the growth and development of HIV infection.

The study found that
  • Less than 10% of South African women in the study had the 'healthy' community of vaginal bacteria.
  • 70% of the study participants had diverse bacterial communities with low amounts of Lactobacillus.
The studies showed that the diverse communities of bacteria were associated with higher level of genital inflammation along with an increased risk of HIV infection.

Differences in Vaginal Microbiome

There are two reasons for the differences in vaginal microbiome
  • Genetic - Some people have hereditary factors that determine the type of bacteria that grow in the vagina.
  • Environmental variables - This includes hygiene, diet, contraception methods, sexual behavior and so on.

Altering the Vaginal Microbiome

The research team have been trying to identify mechanisms by which the vaginal microbiome could be altered to lower vaginal inflammation and to reduce the risk of HIV infection. However, the challenge of increasing Lactobacillus in the vagina is difficult as the use of antibiotics can lower the vaginal microbial load but the composition of bacteria cannot be changed.

Some studies have suggested fecal transplant but they have also shown that the vaginal microbiome returns to baseline after a period of time. Further research needs to be carried out in this regard.

Dr. Kwon further added that more studies were needed to understand the significance of microbial communities in the body and to discern their importance. There is more to research on the microbiome than just their relevance in the gut.

References :
  1. The vaginal microbiome: rethinking health and diseases - (

Source: Medindia

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