Highlights d Single-cell RNA-seq revealed distinct immune profiles in HPVand HPV + HNSCC d B cells, myeloid cells, and CD4+ Tconv cells were divergent by high-dimensional analysis d Multispectral imaging uncovered immune structures (TLSs) associated with HPV + disease d T follicular helper signature was associated with favorable survival in TCGA patients

Reversal of proviral latency is being pursued as a curative strategy for HIV-1 infection. Recent clinical studies of in vivo administration of the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA; vorinostat) show increases in unspliced cellular HIV-1 RNA levels in resting CD4 + T cells. A critical unknown, however, is the proportion of latent proviruses that can be transcriptionally reactivated by SAHA or T-cell activation. In this study, we quantified the fraction of HIV-1 proviruses in resting CD4 + T cells from patients on suppressive antiretroviral therapy that were reactivated ex vivo with SAHA or antibodies to CD3/CD28. At concentrations of SAHA achieved clinically, only 0.079% of proviruses in resting CD4 + T cells were reactivated to produce virions, compared with 1.5% of proviruses in cells treated with anti-CD3/CD28 antibodies after correcting for spontaneous virion production in the medium control. A significant positive correlation (ρ = 0.67, P < 0.001) was found between levels of virions in the supernatant and unspliced cellular HIV-1 RNA following anti-CD3/CD28 treatment, but not following SAHA treatment (ρ = 0.21, P = 0.99). These results reveal that the majority of HIV-1 proviruses are not reactivated by current therapeutic approaches and that more effective means of reversing proviral latency will likely be required to deplete HIV-1 reservoirs.HIV-1 persistence | HIV-1 eradication | HIV-1 cure | fractional provirus expression A ntiretroviral therapy (ART) for HIV-1 infection suppresses viral replication but is not curative. Assays of infectious virus recovery from quiescent CD4 + T cells isolated from patients on ART have revealed the existence of a reservoir of latent, replication competent HIV-1 with a half-life of 44 mo (1-4). In addition, low-level plasma viremia persists indefinitely on ART (5, 6), and the level of virus in plasma rebounds following cessation of ART (7,8). New therapeutic approaches are required to eliminate both persistent low-level viremia and the latent proviral reservoir. A "kick and kill" approach has been proposed in which latency reversing agents, administered in conjunction with ART, will "kick" proviruses out of latency, followed by a "kill" of the infected cells through viral cytopathic effects or immune-mediated cytotoxicity.Histone deacetylase inhibitors (HDACi) have been proposed as latency reversing agents, and single-dose or multidose administration of suberoylanilide hydroxamic acid (SAHA; vorinostat) in vivo was shown to increase expression of unspliced cellular HIV-1 RNA in resting CD4 + T (rCD4) cells in patients on suppressive ART (9, 10). Although three-to fivefold increases in cellular HIV-1 RNA were observed (9), the fraction of latent HIV-1 proviruses that were reactivated by SAHA was not quantified. It is possible that SAHA transcriptionally reactivated many latent proviruses, or alternatively reactivated only a minority of latent proviruses. These two alternatives have very different implications in terms of the impact SAHA coul...

Little is known about the fraction of human immunodeficiency virus type 1 (HIV-1) proviruses that express unspliced viral RNA in vivo or about the levels of HIV RNA expression within single infected cells. We developed a sensitive cell-associated HIV RNA and DNA single-genome sequencing (CARD-SGS) method to investigate fractional proviral expression of HIV RNA (1.3-kb fragment of p6, protease, and reverse transcriptase) and the levels of HIV RNA in single HIV-infected cells from blood samples obtained from individuals with viremia or individuals on long-term suppressive antiretroviral therapy (ART). Spiking experiments show that the CARD-SGS method can detect a single cell expressing HIV RNA. Applying CARD-SGS to blood mononuclear cells in six samples from four HIV-infected donors (one with viremia and not on ART and three with viremia suppressed on ART) revealed that an average of 7% of proviruses (range: 2–18%) expressed HIV RNA. Levels of expression varied from one to 62 HIV RNA molecules per cell (median of 1). CARD-SGS also revealed the frequent expression of identical HIV RNA sequences across multiple single cells and across multiple time points in donors on suppressive ART consistent with constitutive expression of HIV RNA in infected cell clones. Defective proviruses were found to express HIV RNA at levels similar to those proviruses that had no obvious defects. CARD-SGS is a useful tool to characterize fractional proviral expression in single infected cells that persist despite ART and to assess the impact of experimental interventions on proviral populations and their expression.

Head and neck squamous cell carcinoma (HNSCC) is characterized by complex relations between stromal, epithelial, and immune cells within the tumor microenvironment (TME). To enable the development of more efficacious therapies, we aim to study the heterogeneity, signatures of unique cell populations, and cell-cell interactions of non-immune and immune cell populations in 6 human papillomavirus (HPV)+ and 12 HPV– HNSCC patient tumor and matched peripheral blood specimens using single-cell RNA sequencing. Using this dataset of 134,606 cells, we show cell type-specific signatures associated with inflammation and HPV status, describe the negative prognostic value of fibroblasts with elastic differentiation specifically in the HPV+ TME, predict therapeutically targetable checkpoint receptor-ligand interactions, and show that tumor-associated macrophages are dominant contributors of PD-L1 and other immune checkpoint ligands in the TME. We present a comprehensive single-cell view of cell-intrinsic mechanisms and cell-cell communication shaping the HNSCC microenvironment.