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Updated: Jun 25, 2025

Exploring m6A and m5C Epitranscriptomes upon Viral Infection: an Example with HIV
Published on: March 5, 2022
[How do 2'-O-methylations within Human Immunodeficiency Virus type 1 (HIV-1) genome regulate its replication?]
Alice Decombe1, Priscila El-Kazzi1, Sébastien Nisole1
1AFMB (Architecture et fonction des macromolécules biologiques), UMR 7257 - CNRS / Université Aix-Marseille, Marseille, France.
HIV-1 RNA modifications called 2''-O-methylations, added by FTSJ3, have dual effects. They protect the virus from immune sensors like MDA5 but also hinder viral replication, suggesting a complex role in HIV-1 infection.
Area of Science:
- Molecular Biology
- Virology
- Epitranscriptomics
Background:
- HIV-1 genomic RNA undergoes epitranscriptomic modifications, specifically 2'-O-methylations at internal positions.
- These modifications are catalyzed by the cellular methyltransferase FTSJ3.
- 2'-O-methylations play a dual role in HIV-1 pathogenesis, influencing viral genome stability and replication.
Purpose of the Study:
- To investigate the dual pro-viral and antiviral effects of 2'-O-methylations on HIV-1 RNA.
- To elucidate the mechanisms by which these modifications impact viral detection by innate immune sensors and replication.
Main Methods:
- Analysis of HIV-1 genomic RNA modifications.
- Assessment of viral genome protection against innate immune sensors (MDA5) and exonucleases (ISG20).
- Evaluation of the impact of 2'-O-methylations on viral replication in vitro and in quiescent cells.
Main Results:
- 2'-O-methylations shield HIV-1 RNA from MDA5 detection, reducing interferon production and ISG expression.
- These modifications protect the viral genome from ISG20-mediated degradation.
- Conversely, 2'-O-methylations inhibit HIV-1 reverse-transcription in vitro and in quiescent cells.
Conclusions:
- HIV-1 2'-O-methylations exhibit a balance between proviral (immune evasion) and antiviral (replication inhibition) activities.
- Understanding this balance offers potential for therapeutic RNA optimization through selective methylation.
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