Selective persistence of HIV-1-infected T cell clones can occur through immune reprogramming driven by defective, transcriptionally active proviruses

Abstract

People living with HIV (PLWH) on antiretroviral therapy (ART) accumulate primarily defective proviral sequences in genomes of often clonally expanded CD4+ HIV-1 target cells. The majority of viral-derived DNA is transcriptionally active and preferentially found at distinct genomic loci suggesting a selective process driven by integration site-specific crosstalk between viral and host sequences. Focusing on one of the most prominent selected integration loci, the BTB Domain and CNC Homolog 2 (BACH2) gene, we here show mechanistic insights how CD4+ T cells are functionally reprogrammed via exaptation of provirus-derived regulatory sequences during long-term ART. Using a cellular model of BACH2-integrated proviruses, we find that proviral transcription drives aberrant BACH2 protein levels that escape autoregulatory feedback and impose BACH2-dependent transcriptomic changes. By mimicking these changes in primary CD4+ T lymphocytes, we observe that BACH2 drives reprogramming of cells toward a proliferative, precursor memory-like type. These reprogrammed CD4+ T cells possess traits of immune evasion and cellular survival that are signatures of persistent HIV reservoir cells in PLWH. Inhibition of provirus transcriptional activity can mitigate exaptation, suggesting a strategy to offset HIV-driven differentiation and expansion of CD4+ T cells. Finally, our data suggest that provirus exaptation at a second prominently selected proviral integration gene, the Signal Transducer And Activator of Transcription 5B (STAT5B) gene, drives a contrary, effector-like T cell fate, suggesting a multifaceted impact of exaptation on immune homeostasis. Overall, our data suggest that transcriptionally active proviruses, even if structurally defective, modulate target cells through insertional activation of integration genes, a process which we postulate to contribute to the complex immune modulation and dysregulation experienced by ART-suppressed PLWH.