Microbiome’s link to HIV infection risk to be investigated in new $2m study

A new international research collaborative will explore the role of the microbiome in preventing human immunodeficiency virus (HIV).

The $2 million project, funded by the Canadian Institutes of Health Research (CIHR), will be undertaken over a five-year period as part of a collaboration led by the University of Manitoba, Imperial College London and the IrsiCaixa AIDS Research Institute.  

HIV continues to be a major global public health issue and was the cause of 770,000 deaths globally in 2018. The virus targets the immune system and weakens the body’s defences against infections and certain forms of cancer; as it destroys and impairs the function of immune cells, infected individuals gradually become immunodeficient. Effective antiretroviral (ARV) drugs can control the virus and help prevent transmission, but there is currently no cure for HIV.

The microbiome, which refers to the vast collection of microbes living in and on our bodies, has been previously associated with increased risk of HIV infection. However, it has not been studied extensively in the context of HIV prevention technologies, such as anti-retroviral based pre-exposure prophylaxis and vaccines. The new research collaborative will evaluate how differences in the microbiome of the genital tract and gut affect host inflammation, the effectiveness of these drugs and immune responses stimulated by HIV vaccines. These studies may help to improve therapies and technologies to make them more effective for HIV prevention.

"This consortium represents a unique opportunity to assess the effect of the microbiome components on the efficacy of HIV prevention strategies including antiretrovirals and vaccines" Dr Carolina Herrera Co-Principal Investigator and Senior Research Fellow

At Imperial College London, co-principal investigator Dr Carolina Herrera will use cervical and rectal tissue models to evaluate the effect of the microbial flora on the susceptibility to HIV infection and on the efficacy of anti-HIV prevention methods. The Imperial team will make use of samples gathered from two previous clinical trials that tested a vaginal ring delivering an anti-HIV drug (ASPIRE trial) and an HIV vaccine (RV306 trial). Using the results of both studies, researchers will identify the different kinds of bacteria present in individuals who showed a greater risk of HIV infection despite using the ring with drug or receiving the vaccine. They will then work to confirm the effect of these specific bacteria by adding them on small pieces of cervical or rectal tissue that will be infected in the laboratory with HIV and testing the potency of the anti-HIV drug or measuring antibody levels. 

Commenting on the significance of the collaborative, Dr Herrera commented: “After more than 30 years of an HIV/AIDS epidemic, the goal of global protection has not been reached. This consortium brings together ten institutions from five countries and represents a unique opportunity to assess the effect of the microbiome components on the efficacy of HIV prevention strategies including antiretrovirals and vaccines.”

The study will build on co-principal investigator Dr Adam Burgener’s past work which demonstrated that the effectiveness of an anti-HIV gel known as tenofovir is related to the presence of “healthy” lactobacillus bacteria in the vaginal tract, meaning those women who lacked these bacteria gained little or no benefit from the drug. Based at the University of Manitoba, Dr Burgener’s team was the first to show that vaginal bacteria can impact this class of anti-retroviral drugs, and their efficacy can vary more than three-fold depending on what bacteria are dominant in the individual.

This article was adapted from a press release by the University of Manitoba.