CRISPR/Cas9-mediated insertion of HIV LTR within BACH2 promotes expansion of T regulatory-like cells

One key barrier to curative therapies for HIV is the limited understanding of HIV persistence. HIV provirus integration sites (IS) within BACH2 are common, and almost all sites mapped to date are located upstream of the start codon in the same transcriptional orientation as the gene. These unique features suggest the possibility of insertional mutagenesis at this location. Using CRISPR/Cas9-based homology-directed repair in primary human CD4+ T cells, we directly modeled the effects of HIV integration within BACH2 . Integration of the HIV LTR and major splice donor (MSD) increased BACH2 mRNA and protein levels, altered gene expression and promoted selective outgrowth of an activated, proliferative and T regulatory (T reg )-like cell population. In contrast, introduction of the HIV-LTR alone, or an HIV-LTR-MSD construct into STAT5B, a second common HIV IS had no functional impact. Thus, HIV LTR-driven BACH2 expression modulates T cell programming and leads to cellular outgrowth and unique phenotypic changes; findings that support a direct role for IS-dependent HIV-1 persistence.