People able to control HIV has significantly higher levels of Bacteroidales bacteria and lower levels of Clostridiales, as well as a higher expression of genes related to the activation of the immune system
The organs of the human body are home to thousands of microbes that, as a whole, we know as the microbiome. The study of the gut microbiome, in particular, has shown that its composition directly influences human health. An article published by the IrsiCaixa AIDS Research Institute –a center jointly promoted by the “la Caixa” Foundation and the Department of Health of the Generalitat de Catalunya–, in the context of the European project MISTRAL, highlights how the pattern of bacteria housed in the intestine can determine the immune response against an infectious agent such as HIV.
“Thanks to antiretroviral treatment, people with HIV can keep their viral load low enough to prevent transmission of this virus and lead a day-to-day life almost identical to that of people living without HIV”, contextualizes the first author of the article and IrsiCaixa postdoctoral researcher Alessandra Borgognone. “However, we know that 10-20% of people with HIV who start treatment soon after diagnosis can maintain a low viral load even if they temporarily stop taking antiretroviral therapy”, she adds. The scientific literature suggests that this ability to control viral load may be related to the gut microbiome.
To analyse this interplay, IrsiCaixa researchers compared in this study the intestinal microbiomes of people with HIV able and unable to control their viral load after vaccination. To do so, they administered a therapeutic HIV vaccine to these individuals and, during the first 32 weeks post-vaccination, they did not receive antiretroviral treatment. They then separated the individuals into two groups: those who were able to control HIV in the absence of treatment and those who were unable to keep the virus suppressed. What the scientific team observed is that individuals able to control HIV had significantly higher levels of Bacteroidales bacteria and lower levels of Clostridiales –two types of bacteria commonly found in the human gut microbiome– as well as a higher expression of genes related to the activation of the immune system. This Bacteroidales-Clostridiales ratio was also associated with smaller HIV reservoirs.
“This finding highlights the potential of the gut microbiome as a predictive tool in the control of HIV infection, that is, as a marker to predict which people have the necessary conditions to activate the immune system and keep the virus under control,” concludes study leader and IrsiCaixa principal investigator Roger Paredes.