N6-methyladenosine modification of HIV-1 RNA suppresses type-I interferon induction in differentiated monocytic cells and primary macrophages

PLoS Pathog. 2021 Mar 10;17(3):e1009421. doi: 10.1371/journal.ppat.1009421. eCollection 2021 Mar.


N6-methyladenosine (m6A) is a prevalent RNA modification that plays a key role in regulating eukaryotic cellular mRNA functions. RNA m6A modification is regulated by two groups of cellular proteins, writers and erasers that add or remove m6A, respectively. HIV-1 RNA contains m6A modifications that modulate viral infection and gene expression in CD4+ T cells. However, it remains unclear whether m6A modifications of HIV-1 RNA modulate innate immune responses in myeloid cells that are important for antiviral immunity. Here we show that m6A modification of HIV-1 RNA suppresses the expression of antiviral cytokine type-I interferon (IFN-I) in differentiated human monocytic cells and primary monocyte-derived macrophages. Transfection of differentiated monocytic U937 cells with HIV-1 RNA fragments containing a single m6A-modification significantly reduced IFN-I mRNA expression relative to their unmodified RNA counterparts. We generated HIV-1 with altered m6A levels of RNA by manipulating the expression of the m6A erasers (FTO and ALKBH5) or pharmacological inhibition of m6A addition in virus-producing cells, or by treating HIV-1 RNA with recombinant FTO in vitro. HIV-1 RNA transfection or viral infection of differentiated U937 cells and primary macrophages demonstrated that HIV-1 RNA with decreased m6A levels enhanced IFN-I expression, whereas HIV-1 RNA with increased m6A modifications had opposite effects. Our mechanistic studies indicated that m6A of HIV-1 RNA escaped retinoic acid-induced gene I (RIG-I)-mediated RNA sensing and activation of the transcription factors IRF3 and IRF7 that drive IFN-I gene expression. Together, these findings suggest that m6A modifications of HIV-1 RNA evade innate immune sensing in myeloid cells.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine / analogs & derivatives
  • Adenosine / metabolism
  • Gene Expression Regulation / immunology
  • HIV Infections / immunology*
  • HIV-1 / immunology
  • HIV-1 / metabolism*
  • Humans
  • Immunity, Innate / immunology
  • Interferon Type I / biosynthesis*
  • Macrophages / metabolism
  • Macrophages / virology
  • Monocytes / metabolism
  • Monocytes / virology
  • Myeloid Cells / immunology
  • Myeloid Cells / metabolism
  • Myeloid Cells / virology*
  • RNA Processing, Post-Transcriptional / immunology*
  • RNA, Viral / immunology
  • RNA, Viral / metabolism*


  • Interferon Type I
  • RNA, Viral
  • N-methyladenosine
  • Adenosine