Herpes simplex virus 1 (HSV-1) R-loops are targets for APOBEC-mediated innate immunity [RNaseH_DRIP-seq]

Special three-stranded nucleic acid structures, called R-loops, have been considered as efficient targets for APOBEC-mediated mutagenesis because they present an ideal substrate, a persistent single-stranded DNA, for the enzyme.

However, the relationship between R-loops and APOBEC enzyme activity has not been verified and remains to be elucidated. Here, we reveal a mechanistic link between R-loop formation, APOBEC enzyme binding, and APOBEC mutagenesis at viral R-loop targets during virus infection. In a cellular model involving human T lymphoblastoid leukemia cells infected with Herpes simplex virus 1 (HSV-1), we show that APOBEC3A and APOBEC3G binding sites and mutagenesis signatures occur mainly in viral R-loop structures.