Image: Burnet Institute Head of Life Sciences, Professor Gilda Tachedjian

Burnet Head of Life Sciences Professor Gilda Tachedjian will chair an expert session on HIV transmission: Virus, host and microbiome, at the AIDS 2018 conference in Amsterdam this month.

Professor Tachedjian will give a ‘setting the scene’ presentation to kick off the session, which will cover the very early stages of HIV transmission including the role of the local microbiome.

She said the effect of the microbiome on HIV transmission was an “incredibly exciting” area that could inform HIV prevention strategies.

“We’re starting to understand that the vaginal microbiome can influence susceptibility to HIV transmission, and can also impact on the efficacy of topical treatments,” she said.

Recent groundbreaking studies in South Africa have shown that beneficial lactobacilli can help protect young women against HIV while highly diverse vaginal bacteria depleted of lactobacilli can promote HIV transmission by causing mild inflammation in the genital tract.

“It’s a double whammy - inflammation degrades the physical barrier and recruits cells that the virus likes to infect,” Professor Tachedjian explained.

Further research indicates that a diverse range of vaginal bacteria, as well as encouraging harmful inflammation and an HIV-friendly environment, can disrupt the activity of HIV prevention gels by ‘eating up’ antiviral topical drugs.

“People have formulated an antiviral agent as a topical gel for vaginal use (to prevent HIV transmission) but clinical trials haven’t shown great efficacy,” she said.

“One reason which has really come out of the ballpark is that these diverse bacteria actually metabolise, or eat up, the drug so there’s less drug there to do the work.

“It’s really fascinating. In the end I just want to make the point that to develop effective HIV prevention strategies, you really must understand the fundamentals of HIV transmission at the site, including the impact of the microbiome.”

The latest study by Professor Tachedjian’s laboratory, published in the American Society for Microbiology journal, mSphere, shows for the first time that genital secretions collected from women with beneficial microbiota contain high levels of lactic acid produced by bacteria largely responsible for killing HIV in these secretions.

“These studies advance our understanding of the mechanisms by which vaginal microbiota modulate HIV susceptibility and could lead to novel strategies to prevent women from acquiring HIV or transmitting the virus during vaginal intercourse and vaginal birth,” Professor Tachedjian said.

Speakers at the Virus, host and microbiome AIDS 2018 session include

• Jonathan Carlson from Microsoft, US, on Why the transmitted virus wins;
• Jo-Ann Passmore, University of Cape Town, South Africa, on Local bugs and HIV transmission: the role of the local microbiome;
• Zabrina Brumme, Simon Fraser University, Canada on Seeding the latent reservoir following transmission, and
• Thumbi Ndung’u, Africa Health Research Institute, South Africa, on Early events in HIV transmission.

The International AIDS Conference is the largest conference on any global health issue.

This year it will be hosted in Amsterdam, the Netherlands, 23-27 July, with the theme Breaking Barriers, Building Bridges, and a focus on more effectively reaching key populations.

A team of life science researchers and public health specialists from Burnet will present at AIDS 2018 on a range of topics.

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