Bulk BCR sequencing primers.

Chronic HIV infection drives B cell dysfunction associated with the accumulation of tissue-like memory (TLMs) and activated memory B cells (MBCs) but decline in resting memory B cells. TLMs express multiple inhibitory receptors and lack response to soluble antigens. However, their origin and the mechanisms driving their expansion in HIV infection remain unclear. From bulk heavy chain BCR sequencing of MBC subsets from 5 PLWH with no detectable viremia, we hypothesized that TLMs (CD21- CD27- B cells) were significantly less mutated but also less diverse than other MBCs, suggesting an enrichment for innate-like B cells or that they belong to a less mature subset. Subsequent detailed multi-omics study of an immune response to a transient HIV viremia in an elite controller demonstrated a functional increase in Env-reactive IgG and MBCs with non-TLM phenotype. Single-cell RNA/BCR sequencing of PBMCs enriched for B cells revealed an orchestrated TNF-α response followed by interferon-α and -γ responses across all B cell subsets. This study provides new insights into multifaceted functional B cell response to transient HIV viremia and highlights TLM heterogeneity.