The importance of CD8⁺T-cell responses in the control of human immunodeficiency virus type 1 (HIV-1) infection has been demonstrated, yet few studies have been able to correlate these responses with markers of HIV-1 disease progression. This study measured cell-mediated immune responses using peripheral blood mononuclear cells (PBMC) obtained from 27 patients with chronic HIV-1 infection, the majority of whom were off antiretroviral therapy. The ELISPOT assay was used to detect gamma interferon-secreting PBMC after stimulation with overlapping HIV-1 peptides spanning the Gag, Pol, Env, and Nef proteins in addition to the baculovirus-derived p24 and gp160 proteins. All volunteers had responses to at least one HIV-1-specific peptide. All but one of the subjects (96%) responded to the Gag peptide pool, and 86% responded to the Pol and/or Nef peptide pools. The magnitude and the breadth of T-cell responses directed to either the Gag or p24 peptide pools correlated inversely with viral load in plasma (r= −0.60,P< 0.001 andr= −0.52,P< 0.005, respectively) and directly with absolute CD4⁺T-cell counts (r= 0.54,P< 0.01 andr= 0.39,P< 0.05, respectively) using the Spearman rank correlation test. Responses to the Pol and integrase peptide pools also correlated with absolute CD4⁺T-cell counts (r= 0.45,P< 0.05 andr= 0.49,P< 0.01, respectively). No correlation with markers of disease progression was seen with specific T-cell responses directed toward the Env or Nef peptides. These data serve as strong evidence that major histocompatibility complex class I presentation of Gag peptides is an essential feature for any HIV-1 vaccine designed to elicit optimal CD8⁺T-cell responses.

Despite the seemingly important role of cytotoxic T-lymphocyte (CTL) responses in human immunodeficiency virus (HIV) disease pathogenesis, their measurement has relied on a variety of different techniques. We utilized three separate methodologies for the detection of CTLs in a cohort of HIV-infected individuals who were also human leukocyte antigen A2 (HLA-A2) positive. Among the different CTL assays, a correlation was seen only when the Gag epitope-specific HLA A*0201-restricted tetramer assay was compared with the ELISPOT assay performed after stimulation with the Gag epitope; however, this correlation was of borderline statistical significance. On average, the tetramer reagent detected a 10-fold-higher number of cells than were seen to produce gamma interferon by the ELISPOT assay. The implications of this CTL assay comparison and the possibility of phenotypic differences in HIV-specific CD8⁺T lymphocytes are discussed.

SARS-CoV-2 causes a wide spectrum of clinical manifestations and significant mortality. Studies investigating underlying immune characteristics are needed to understand disease pathogenesis and inform vaccine design. In this study, we examined immune cell subsets in hospitalized and nonhospitalized individuals. In hospitalized patients, many adaptive and innate immune cells were decreased in frequency compared with those of healthy and convalescent individuals, with the exception of an increase in B lymphocytes. Our findings show increased frequencies of T cell activation markers (CD69, OX40, HLA-DR, and CD154) in hospitalized patients, with other T cell activation/exhaustion markers (PD-L1 and TIGIT) remaining elevated in hospitalized and nonhospitalized individuals. B cells had a similar pattern of activation/exhaustion, with increased frequency of CD69 and CD95 during hospitalization followed by an increase in PD1 frequencies in nonhospitalized individuals. Interestingly, many of these changes were found to increase over time in nonhospitalized longitudinal samples, suggesting a prolonged period of immune dysregulation after SARS-CoV-2 infection. Changes in T cell activation/exhaustion in nonhospitalized patients were found to positively correlate with age. Severely infected individuals had increased expression of activation and exhaustion markers. These data suggest a prolonged period of immune dysregulation after SARS-CoV-2 infection, highlighting the need for additional studies investigating immune dysregulation in convalescent individuals.

Pathogenic Th cells and myeloid cells are involved in the pathogenesis of multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), an animal model of MS. The JAK/STAT pathway is used by numerous cytokines for signaling and is critical for development, regulation, and termination of immune responses. Dysregulation of the JAK/STAT pathway has pathological implications in autoimmune and neuroinflammatory diseases. Many of the cytokines involved in MS/EAE, including IL-6, IL-12, IL-23, IFN-γ, and GM-CSF, use the JAK/STAT pathway to induce biological responses. Thus, targeting JAKs has implications for treating autoimmune inflammation of the brain. We have used AZD1480, a JAK1/2 inhibitor, to investigate the therapeutic potential of inhibiting the JAK/STAT pathway in models of EAE. AZD1480 treatment inhibits disease severity in myelin oligodendrocyte glycoprotein-induced classical and atypical EAE models by preventing entry of immune cells into the brain, suppressing differentiation of Th1 and Th17 cells, deactivating myeloid cells, inhibiting STAT activation in the brain, and reducing expression of proinflammatory cytokines and chemokines. Treatment of SJL/J mice with AZD1480 delays disease onset of PLP-induced relapsing-remitting disease, reduces relapses and diminishes clinical severity. AZD1480 treatment was also effective in reducing ongoing paralysis induced by adoptive transfer of either pathogenic Th1 or Th17 cells. In vivo AZD1480 treatment impairs both the priming and expansion of T cells and attenuates Ag presentation functions of myeloid cells. Inhibition of the JAK/STAT pathway has clinical efficacy in multiple preclinical models of MS, suggesting the feasibility of the JAK/STAT pathway as a target for neuroinflammatory diseases.

HIV-1 integration is prone to a high rate of failure, resulting in the accumulation of unintegrated viral genomes (uDNA) in vivo and in vitro. uDNA can be transcriptionally active, and circularized uDNA genomes are biochemically stable in non-proliferating cells. Resting, non-proliferating CD4 T cells are prime targets of HIV-1 infection and latently infected resting CD4 T cells are the major barrier to HIV cure. Our prior studies demonstrated that uDNA generates infectious virions when T cell activation follows rather than precedes infection. Here, we characterize in primary resting CD4 T cells the dynamics of integrated and unintegrated virus expression, genome persistence and sensitivity to latency reversing agents. Unintegrated HIV-1 was abundant in directly infected resting CD4 T cells. Maximal gene expression from uDNA was delayed compared with integrated HIV-1 and was less toxic, resulting in uDNA enrichment over time relative to integrated proviruses. Inhibiting integration with raltegravir shunted the generation of durable latency from integrated to unintegrated genomes. Latent uDNA was activated to de novo virus production by latency reversing agents that also activated latent integrated proviruses, including PKC activators, histone deacetylase inhibitors and P-TEFb agonists. However, uDNA responses displayed a wider dynamic range, indicating differential regulation of expression relative to integrated proviruses. Similar to what has recently been demonstrated for latent integrated proviruses, one or two applications of latency reversing agents failed to activate all latent unintegrated genomes. Unlike integrated proviruses, uDNA gene expression did not down modulate expression of HLA Class I on resting CD4 T cells. uDNA did, however, efficiently prime infected cells for killing by HIV-1-specific cytotoxic T cells. These studies demonstrate that contributions by unintegrated genomes to HIV-1 gene expression, virus production, latency and immune responses are inherent properties of the direct infection of resting CD4 T cells. Experimental models of HIV-1 latency employing directly infected resting CD4 T cells should calibrate the contribution of unintegrated HIV-1.

Recent observational studies indicate an association between the use of hormonal contraceptives and acquisition and transmission of HIV-1. The biological and immunological mechanisms underlying the observed association are unknown. Depot medroxyprogesterone acetate (DMPA) is a progestin-only injectable contraceptive that is commonly used in regions with high HIV-1 prevalence. Here we show that medroxyprogesterone acetate (MPA) suppresses the production of key regulators of cellular and humoral immunity involved in orchestrating the immune response to invading pathogens. MPA inhibited the production of interferon (IFN)-γ, IL-2, IL-4, IL-6, IL-12, TNFα, macrophage inflammatory protein-1α (MIP-1α), and other cytokines and chemokines by peripheral blood cells and activated T cells and reduced the production of IFNα and TNFα by plasmacytoid dendritic cells in response to Toll-like receptor-7, -8, and -9 ligands. Women using DMPA displayed lower levels of IFNα in plasma and genital secretions compared with controls with no hormonal contraception. In addition, MPA prevented the down-regulation of HIV-1 coreceptors CXCR4 and CCR5 on the surface of T cells after activation and increased HIV-1 replication in activated peripheral blood mononuclear cell cultures. The presented results suggest that MPA suppresses both innate and adaptive arms of the immune system resulting in a reduction of host resistance to invading pathogens.