HIV and microbiota: the gut virome reveals its secrets
According to a new study 1, the viral component of the gut microbiota may be involved in the progression of HIV infection. Some viruses may even serve as markers for monitoring the recovery of immunity and predicting the effectiveness of treatments.
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Extreme depletion of CD4 T cells, inflammation, bacterial dysbiosis, disruption of the epithelial barrier, microbial translocation... HIV’s impact on the gastrointestinal tract is now well documented.
While no research has yet succeeded in defining a bacterial dysbiosis signature associated with HIV, we do know that enteropathy is involved in the chronic activation of the infection and in the development of immunodeficiency.
39 million In 2023, 39 million people were affected by HIV. ²
Better understanding the role viruses play in the gut microbiota during HIV infection
The viral component of the gut microbiota is less well known than the bacterial component. To what extent does it play a part in this process? To find out, scientists in Mexico City investigated whether our ‘virome’ is associated with HIV infection and immunodeficiency. 1
They began by comparing the CD4 T cell count and gut bacteriome and virome (viral RNA and DNA) of 92 untreated HIV-positive individuals with those of 52 healthy individuals at risk.
To better understand the association between gut microbiota composition, HIV-related immunodeficiency, and immune recovery, they followed 14 HIV-positive individuals receiving antiretroviral therapy (ART) for two years. Blood and stool samples were taken at baseline (before ART) and at 2, 6, 12, and 24 months after the start of treatment.
The results showed that HIV-positive individuals do indeed have reduced alpha bacterial diversity, with an increase in Enterococcus, Streptococcus, and Coprococcus in those at an advanced stage of infection. However, no clear signature could be identified.
Marked expansion of certain viruses
Compared with HIV-seronegative volunteers, individuals suffering from severe immunodeficiency (CD4 count < 350) showed radical changes in the composition of their gut virome:
- Increase in sequences of Anelloviridae (anelloviruses), Adenoviridae, and Papillomaviridae
- Decrease in plant viruses of the Tobamovirus genus
No Anelloviridae were detected in HIV-seronegative individuals.
The researchers believe that this expansion of viruses could contribute to the pathogenesis of AIDS by damaging the gut barrier and promoting inflammation.
The data also showed a striking link between HIV-associated immunodeficiency and the detection of Anelloviridae sequences, which were completely absent in the 53 HIV-negative individuals. In highly immunocompromised individuals, the abundance of anelloviruses decreased progressively during ART.
A predictive tool?
Another finding: the detection of anelloviruses prior to treatment independently predicts poor immune recovery.
Despite the limitations of this study (majority of subjects male, dietary factors not taken into account, etc.), it suggests that the detection of anellovirus sequences in stool could be used to predict and monitor immune recovery during ART.
Another step forward in our understanding of the gut microbiota, but above all a small step forward in the fight against HIV, a virus which, according to the WHO, affected 39 million people and caused 630,000 deaths in 2023. 2
