Despite significant improvements in therapy, the HIV/AIDS pandemic remains an important threat to public health. Current treatments fail to eradicate HIV as proviral DNA persists in long-living cellular reservoirs, leading to viral rebound whenever treatment is discontinued. Hence, a better understanding of viral reservoir establishment and maintenance is required to develop novel strategies to destroy latently infected cells, and/or to durably silence the latent provirus in infected cells. Whereas the mechanism of integration has been well studied from a catalytic point of view, it remains unknown how integration site selection and transcription are linked. In recent years, evidence has grown that lens epithelium-derived growth factor p75 (LEDGF/p75) is the main determinant of HIV integration site selection and that the integration site affects the transcriptional state of the provirus. LEDGINs have been developed as small molecule inhibitors of the interaction between LEDGF/p75 and integrase. Recently, it was shown that LEDGIN treatment in cell culture shifts the residual integrated provirus towards the inner nuclear compartment and out of transcription units in a dose dependent manner. This LEDGIN-mediated retargeting increased the proportion of provirus with a transcriptionally silent phenotype and the residual reservoir proved refractory to reactivation in vitro. LEDGINs provide us with a research tool to study the link between integration and transcription, a quintessential question in retrovirology. LEDGIN-mediated retargeting of the residual reservoirs provides a novel potential “block-and-lock” strategy as a functional cure of HIV infection.
Light and shadow on the mechanisms of integration site selection in yeast Ty retrotransposon families