Simian Immunodeficiency Virus Research Articles

Longitudinal analysis of rhesus macaque metabolome during acute SIV infection reveals disruption in broad metabolite classes.

Despite significant advances in antiretroviral therapy and pre-exposure prophylaxis, HIV remains a global challenge. Understanding the underlying immune mechanisms is critical for improving HIV control and therapeutic development. Cellular metabolism represents a crucial yet underappreciated area of immune system function. Metabolite availability and metabolic pathway preferences directly influence the functional response capacity of immune cells and are highly dysregulated during HIV infection. To further the understanding of metabolic impacts of HIV infection, we utilized cutting-edge mass spectrometry-based metabolome interrogation to measure over 500 metabolites using an acute simian immunodeficiency virus infection model in rhesus macaques. Our comprehensive analysis provides insights into the dynamic metabolic landscape throughout early infection, revealing both known and novel metabolic signatures. These findings enhance our understanding of the complex interplay between metabolism and immunity in lentiviral infections, potentially informing new strategies for early detection, prevention, and treatment of HIV.

Antibody prophylaxis may mask subclinical SIV infections in macaques.

Broadly neutralizing antibodies (bNAbs) show potential to prevent human immunodeficiency virus (HIV-1) infection in humans1. However, there are limited data on the antibody concentrations required to prevent infection. Clinical trials of bNAb prophylaxis have demonstrated partial efficacy2, but the sampling frequency typically does not allow precise timing of infection events and concurrent antibody levels. Here, using simian immunodeficiency virus (SIV) infection of rhesus macaques, we show that although potent bNAbs can delay the onset of acute viremia, subclinical infections occur while bNAb levels remain high. Serial SIV challenge of monkeys given partially and fully neutralizing bNAbs revealed that 'viral blips'-low and transient plasma viremia-often occur while serum bNAb concentrations are well above currently accepted protective levels. To understand the precise timing of the infections resulting in such blips, we performed plasma viral sequencing on monkeys that were serially challenged with genetically barcoded SIV after bNAb administration. These analyses showed that subclinical infections occurred in most animals that were given potent bNAb prophylaxis. These subclinical infections occurred while antibody concentrations were 2- to400-fold higher than the levels required to prevent fully viremic breakthrough infection. This study demonstrates that immunoprophylaxis can mask subclinical infections, which may affect the interpretation of prophylactic HIV-1 bNAb clinical trials.

Whole-body PET imaging of simian immunodeficiency virus using gp120-targeting probes fails to reveal regions of specific uptake in rhesus macaques.

Following the initial reports demonstrating the feasibility of immunoPET imaging of simian immunodeficiency virus (SIV) using gp120-targeting monoclonal antibodies in non-human primates, replication efforts of the imaging system in human immunodeficiency virus (HIV)-infected individuals have yielded conflicting results. Herein, we used two anti-gp120 antibodies, 7D3 and ITS103.01LS-F(ab')2, to interrogate the reproducibility of gp120-targeting probes for immunoPET imaging of SIV in rhesus macaques. The binding affinity estimates of 89Zr radiolabeled 7D3 and ITS103.01LS-F(ab')2 to SIV gp120, and the in-vitro and ex-vivo binding specificities of [89Zr]Zr-7D3 and [89Zr]Zr-ITS103.01LS-F(ab')2 to SIV Env expressing cells, primary cells, and tissue sections from uninfected and SIV-infected macaques were obtained through competition assays. The biodistributions of [89Zr]Zr-7D3 and [89Zr]Zr-ITS103.01LS-F(ab')2 were performed with static PET scans up to 6 days post-injection in 20 rhesus macaques and the standardized uptake values in various tissues were compared between SIV-infected and uninfected controls. Despite the demonstrated nanomolar affinity of [89Zr]Zr-7D3 and [89Zr]Zr-ITS103.01LS-F(ab')2 to SIV gp120, and strong binding specificity to SIV gp120 cell lines, we observed no discernible differences in their binding in primary cells, tissue sections of secondary lymphoid organs, in-vivo probe uptake between SIV-infected and uninfected macaques, or ex-vivo validation necropsies. While the probes remained stable in-vivo, only [89Zr]Zr-ITS103.01LS-F(ab')2 in chronic plasma retained its binding specificity to SIV gp120, with [89Zr]Zr-7D3 experiencing a > 97% reduction in binding to gp120 due to competition from endogenous antibodies at the 7D3 binding site. The overall absence of specific uptake suggests inadequate binding potential (ligand affinity x target molarity) for these probes to effectively image SIV or HIV in-vivo, warranting further investigation into the lack of reproducibility observed with earlier non-human primate SIV imaging and conflicting human studies.

SIV infection induces alterations in gene expression and loss of interneurons in Rhesus Macaque frontal cortex during early systemic infection

Understanding the neurobiological mechanisms underlying HIV-associated neurocognitive decline in people living with HIV is frequently complicated by an inability to analyze changes across the course of the infection and frequent presence of comorbid psychiatric and substance use disorders. Preclinical non-human primate simian immunodeficiency virus (SIV) models help address these shortcomings. However, SIV studies frequently target protracted endpoints, limiting our understanding of the neuromolecular alterations during the early post-infection window. To begin to address this knowledge gap, we utilized single nuclei transcriptomics to examine frontal cortex samples of rhesus macaques 10- and 20-days post-SIV infection, compared to non-infected controls. We identify and validated a decrease in inhibitory neurons during the early post infection window, representing a potential substrate of longer-term injury and neurocognitive impairment in people living with HIV. Differential expression identified alterations in cellular subtype gene expression that persisted over the 20-day time course and short-lived differences only detected at 10-days post-SIV infection. In silico predicted regulatory mechanisms and dysregulated neural signaling pathways are presented. Analysis of cell-cell interaction networks identify altered signal pathways in the frontal cortex that may represent regional alterations in cell-cell communications. In total, these results identify cell type-specific molecular mechanisms putatively capable of underlying long-term neurocognitive alterations in persons living with HIV.

Microbial remodeling of gut tryptophan metabolism and indole-3-lactate production regulate epithelial barrier repair and viral suppression in human and simian immunodeficiency virus infections.

Gut inflammatory diseases cause microbial dysbiosis. Human immunodeficiency virus-1 (HIV) infection disrupts intestinal integrity, subverts repair/renewal pathways, impairs mucosal immunity and propels microbial dysbiosis. However, microbial metabolic mechanisms driving repair mechanisms in virally inflamed gut are not well understood. We investigated the capability and mechanisms of gut microbes to restore epithelial barriers and mucosal immunity in virally inflamed gut by using a multipronged approach: an in vivo simian immunodeficiency virus (SIV)-infected nonhuman primate model of HIV/AIDS, ex vivo HIV-exposed human colorectal explants and primary human intestinal epithelial cells. SIV infection reprogrammed tryptophan (TRP) metabolism, increasing kynurenine catabolite levels that are associated with mucosal barrier disruption and immune suppression. Administration of Lactiplantibacillus plantarum or Bifidobacterium longum subsp. infantis into the SIV-inflamed gut lumen in vivo resulted in rapid reprogramming of microbial TRP metabolism towards indole-3-lactic acid (ILA) production. This shift accelerated epithelial repair and enhanced anti-viral defenses through induction of IL-22 signaling in mucosal T cells and aryl hydrocarbon receptor activation. Additionally, ILA treatment of human colorectal tissue explants ex vivo inhibited HIV replication by reducing mucosal inflammatory cytokine production and cell activation. Our findings underscore the therapeutic potential of microbial metabolic reprogramming of TRP-to-ILA and mechanisms in mitigating viral pathogenic effects and bolstering mucosal defenses for HIV eradication.

SIV monoclonal antibody administration spanning treatment interruption in macaques delays viral rebound and selects escape variants

HIV-1 envelope broadly neutralizing antibodies represent a promising component of HIV-1 cure strategies. To evaluate the therapeutic efficacy of combination monoclonal antibodies (mAbs) in a rigorous nonhuman primate model, we tested different combinations of simian immunodeficiency virus (SIV) neutralizing mAbs in SIVmac251-infected rhesus macaques. Antiretroviral therapy-suppressed animals received anti-SIV mAbs targeting multiple Env epitopes spanning analytical treatment interruption (ATI) in 3 groups (n = 7 each): i) no mAb; ii) 4-mAb combination; and iii) 2-mAb combination. Each mAb was administered at 15 mg/kg, and both mAb-treated groups received ITS103.01, a highly potent CD4-binding site targeting antibody. mAb treatment delayed viral rebound, lowered rebound viremia setpoint and viral diversity, and extended animal lifespan. Compared to controls, for which viremia rebounded 2 wk following ATI, mAb infusion delayed rebound for both groups (P = 0.0003). Animals that received the 4-mAb regimen rebounded 3 to 6 wk post-ATI while the 2-mAb regimen rebounded 5 to 22 wk post-ATI. Envelope escape mutations emerged in rebound virus of mAb-treated animals that abrogated neutralization by ITS103.01, the most potent in the cocktail. These data demonstrate in vivo antiviral activity of SIV mAbs in the context of ATI via immune pressure dominated by the most potent mAb and highlight their potential in adjunctive therapeutic studies.

Increased Chemokine Production is a Hallmark of Rhesus Macaque Natural Killer Cells Mediating Robust Anti-HIV Envelope-Specific Antibody-Dependent Cell-Mediated Cytotoxicity.

Antibody-dependent cell-mediated cytotoxic (ADCC) response mediated by natural killer (NK) cells correlates with decreased infection risk in studies involving simian immunodeficiency virus (SIV)/simian-human immunodeficiency virus (SHIV), and human immunodeficiency virus (HIV) vaccine candidates. Currently, the heterogeneities of the functional subset of rhesus macaque natural killer (RMNK) cells are under-characterized. We engaged the RMNK cells with ADCC-mediating anti-HIV-1 monoclonal antibodies (ADCCAbs) or anti-CD16 antibodies and used CD107a expression as the surrogate marker for RMNK cells actively involved in ADCC. CD107a+ and CD107a- populations were analyzed individually using single-cell RNA sequencing. Subsets of CD107a+ RMNK cells produced more chemokines than the others, suggesting that these cells not only eliminate infected cells but also provide immunoregulatory signals and potentially curb HIV-1 replication. Crosslinking of Fc gamma receptor IIIa via anti-CD16 antibodies resulted in a significantly higher percentage of degranulating cells than via ADCCAbs. However, the magnitude of degranulation and chemokine production was reduced by 6- to 30-fold. The quality and quantity of receptor engagement are important determinants of achieving an optimal level of the RMNK response.

Transformation of brain myeloid cell populations by SIV in rhesus macaques revealed by multiomics

The primary immune constituents in the brain, microglia and macrophages, are the target for HIV in people and simian immunodeficiency virus (SIV) in nonhuman primates. This infection can lead to neurological dysfunction, known as HIV-associated neurocognitive disorder (HAND). Given the gaps in our knowledge on how these cells respond in vivo to CNS infection, we perform single-cell multiomic sequencing, including gene expression and ATAC-seq, on myeloid cells from the brains of rhesus macaques with SIV-induced encephalitis (SIVE) as well as uninfected controls. We find that SIVE significantly changes the myeloid cell populations. In SIVE, microglia-like cells express high levels of chemoattractants capable of recruiting highly activated CAM-like cells to the site of infection/inflammation. A unique population of microglia-like cells is found in which the chromatin accessibility of genes diverges from their RNA expression. Additionally, we observe a dramatic shift of upstream gene regulators and their targets in brain myeloid cells during SIVE. This study further uncovers the transcriptome, gene regulatory events, and potential roles of different brain myeloid phenotypes in SIVE. This might deepen the understanding of SIVE/HIVE and enlighten the therapeutic development.

Viremic non-progression in HIV/SIV infection: A tied game between virus and host.

High-efficacy antiretroviral treatment (ART) has been a game-changer for HIV/AIDS pandemic, but incomplete CD4+ Tcell recovery and persistent chronic immune activation still affect HIV-suppressed people. Exceptional cases of HIV infection that naturally exhibit delayed disease progression provide invaluable insights into protective biological mechanisms with potential clinical application. Viremic non-progressors (VNPs) represent an extremely rare population of individuals with HIV, characterized by preservation of the CD4+ Tcell compartment despite persistent high levels of viral load (>10,000 copies/mL). While only a few studies have investigated the immunovirological characteristics of adult and pediatric VNPs, most of our knowledge about this phenotype stems from its non-human-primate counterpart, the natural simian immunodeficiency virus (SIV) hosts. In this review, we synthesize the insights gained from recent studies of natural SIV hosts and VNPs and evaluate the potential similarities and differences in the mechanisms that underlie the absence of pathogenesis, with special focus on the control of immune activation.

HIV-1 Vpu and SARS-CoV-2 ORF3a proteins disrupt STING-mediated activation of antiviral NF-κB signaling.

Activation of the stimulator of interferon genes (STING) pathway by cytosolic DNA leads to the activation of the transcription factors interferon regulatory factor 3 (IRF3) and nuclear factor κB (NF-κB). Although many viruses produce proteins that inhibit IRF3-dependent antiviral responses, some viruses produce proteins that inhibit STING-induced NF-κB activation without blocking IRF3 activation. Here, we found that STING-activated, NF-κB-dependent, and IRF3-independent innate immunity inhibited the replication of the DNA virus herpes simplex virus type 1 (HSV-1), the RNA virus coxsackievirus A16 (CV-A16), and the retrovirus HIV-1. The HIV-1 nonstructural protein Vpu bound to STING and prevented it from interacting with the upstream NF-κB pathway kinase inhibitor of NF-κB subunit β (IKKβ), thus blocking NF-κB signaling. This function of Vpu was conserved among Vpu proteins from diverse HIV-1 and simian immunodeficiency virus strains and was distinct from its action in disrupting other host antiviral pathways. Furthermore, the ORF3a protein from the coronavirus SARS-CoV-2 also promoted viral replication by interacting with STING and blocking STING-induced activity of NF-κB but not of IRF3. These findings demonstrate that diverse viral proteins have convergently evolved to selectively inhibit NF-κB-mediated innate immunity downstream of STING activation, suggesting that targeting this pathway may represent a promising antiviral strategy.

Exploitation of Unconventional CD8 T-Cell Responses Induced by Engineered Cytomegaloviruses for the Development of an HIV-1 Vaccine.

After four decades of intensive research, traditional vaccination strategies for HIV-1 remain ineffective due to HIV-1's extraordinary genetic diversity and complex immune evasion mechanisms. Cytomegaloviruses (CMV) have emerged as a novel type of vaccine vector with unique advantages due to CMV persistence and immunogenicity. Rhesus macaques vaccinated with molecular clone 68-1 of RhCMV (RhCMV68-1) engineered to express simian immunodeficiency virus (SIV) immunogens elicited an unconventional major histocompatibility complex class Ib allele E (MHC-E)-restricted CD8+ T-cell response, which consistently protected over half of the animals against a highly pathogenic SIV challenge. The RhCMV68-1.SIV-induced responses mediated a post-infection replication arrest of the challenge virus and eventually cleared it from the body. These observations in rhesus macaques opened a possibility that MHC-E-restricted CD8+ T-cells could achieve similar control of HIV-1 in humans. The potentially game-changing advantage of the human CMV (HCMV)-based vaccines is that they would induce protective CD8+ T-cells persisting at the sites of entry that would be insensitive to HIV-1 evasion. In the RhCMV68-1-protected rhesus macaques, MHC-E molecules and their peptide cargo utilise complex regulatory mechanisms and unique transport patterns, and researchers study these to guide human vaccine development. However, CMVs are highly species-adapted viruses and it is yet to be shown whether the success of RhCMV68-1 can be translated into an HCMV ortholog for humans. Despite some safety concerns regarding using HCMV as a vaccine vector in humans, there is a vision of immune programming of HCMV to induce pathogen-tailored CD8+ T-cells effective against HIV-1 and other life-threatening diseases.

Isolation and structure of broad SIV-neutralizing antibodies reveal a proximal helical MPER epitope recognized by a rhesus multi-donor class.

The membrane-proximal external region (MPER) of the HIV-1 envelope is a target for broadly neutralizing antibodies (bnAbs), and vaccine-elicited MPER-directed antibodies have recently been reported from a human clinical trial. In this study, we sought to identify MPER-directed nAbs in simian immunodeficiency virus (SIV)-infected rhesus macaques. We isolated four lineages of SIV MPER-directed nAbs from two SIV-infected macaques. The nAbs displayed low potency but up to 90% breadth on a 20-strain SIV panel. Crystal structures of representative nAbs in complex with SIV MPER peptides revealed the SIV antibodies to bind a helical epitope at the N-terminal (proximal) region of the MPER, defining a reproducible multi-donor class encompassing all four lineages. HIV-1 comparison showed that this class of SIV MPER-directed antibodies targets a helical region overlapping that targeted by human vaccine-elicited ones. Thus, a prevalent and reproducible class of SIV bnAbs recognizes an epitope similar to that recently observed in an HIV-1-vaccine trial.

It's all in the gut: the central role of the gut and microbiome in preventing disease progression in simian immunodeficiency viruses infected African nonhuman primates.

Typically, both HIV-infected humans and simian immunodeficiency virus (SIV)-infected Asian nonhuman primates (NHPs) eventually progress to AIDS, while African NHPs that are natural hosts of SIV do not, in spite of life-long, high levels of viral replication. Lack of disease progression in African NHPs is not due to some adaptation by the virus, but rather to host adaptations to the virus. Central to these adaptations is maintenance of the gut integrity during acute viral replication and inflammation, which allows natural hosts to avoid the chronic inflammation characteristic to pathogenic HIV/SIV infection. It has been recently shown that natural hosts of SIVs, such as the African green monkey (AGM), avoid damage to the mucosal epithelium through wound healing mechanisms, possibly with the contribution of a unique anti-inflammatory microbiome. Furthermore, these mechanisms are independent of viral replication, and CD4 + T-cell activation or depletion. Future SIV research on natural hosts should focus on further elucidating the anti-inflammatory state of their gut, and the role of microbiome/dysbiosis in the pathogenesis of SIV infection, with the goal of development new regiments or treatments to reduce or even halt the vicious cycle of gut damage and inflammation triggered by pathogenic HIV/SIV infection.

Deubiquitinase USP37 enhances the anti-HIV-2/SIV ability of the host restriction factor SAMHD1.

The Vpx protein encoded by HIV-2/simian immunodeficiency virus (SIV) can antagonize the restriction of the host intrinsic restriction factor, SAMHD1, in nondividing cells by promoting its polyubiquitination and subsequent degradation, thereby facilitating viral replication and immune evasion. However, the role of deubiquitinating enzymes (DUBs) in the dynamics of virus and host remains poorly understood. Here, we demonstrate that DUB USP37 significantly reverses the Vpx-mediated degradation of SAMHD1 in various HIV-2/SIV subtypes by interacting with SAMHD1 and removing its ubiquitin chains. Notably, USP37 deubiquitinates SAMHD1 by directly recognizing SAMHD1 rather than by targeting the E3 ubiquitin ligase. The deubiquitinase activity of USP37 and its ubiquitin interacting motifs are essential for the deubiquitination of SAMHD1, whereas the phosphorylation state of USP37 does not influence its activity. Additionally, USP37 enhances the suppression of the retrotransposition of LINE-1 elements by SAMHD1 via stabilizing SAMHD1. Our findings provide important evidence that enhancing the deubiquitinating activity of some DUBs results in the stability of the host restriction factor and might be a viable strategy against HIV/SIV infections.IMPORTANCESAMHD1 is a multifunctional protein, including restricting virus replication, maintaining genomic integrity through DNA repair, modulating the immune response by influencing the production of type I interferons and other cytokines, and affecting cancer cell proliferation and sensitivity to chemotherapy. However, HIV-2/simian immunodeficiency virus (SIV)-encoded Vpx and the host E3 ligase TRIM21 can induce the degradation of SAMHD1 via the ubiquitin-proteasome pathway. Therefore, it is necessary to find the strategy to stabilize SAMHD1. Our study demonstrates that the deubiquitinase USP37 reverses Vpx- and TRIM21-mediated degradation of SAMHD1, thereby inhibiting SIV replication and LINE-1 activity by stabilizing SAMHD1. Thus, we report a novel role of USP37, which represents a potentially useful target for the development of new drugs.

A penta-component mpox mRNA vaccine induces protective immunity in nonhuman primates

The recent worldwide outbreaks of mpox prioritize the development of a safe and effective mRNA vaccine. The contemporary mpox virus (MPXV) exhibits changing virological and epidemiological features, notably affecting populations already vulnerable to human immunodeficiency virus (HIV). Herein, we profile the immunogenicity of AR-MPXV5, a penta-component mRNA vaccine targeting five specific proteins (M1R, E8L, A29L, A35R, and B6R) from the representative contemporary MPXV clade II strain, in both naive and simian immunodeficiency virus (SIV)-infected nonhuman primates. Immunization with two doses of AR-MPXV5 to cynomolgus macaques effectively elicits antibody responses and cellular responses. Importantly, based on the challenge model with a contemporary MPXV clade II strain, AR-MPXV5 demonstrates effective efficacy in preventing skin lesions, eliminating viremia and reducing viral loads in multiple tissues after challenge in naive male animals. More importantly, AR-MPXV5 is well-tolerated in stable chronic SIV-infected rhesus monkeys, while eliciting comparable MPXV-specific humoral and cellular responses in both naive and SIV-infected monkeys. Together, these results support further clinical development of the AR-MPXV5 vaccine.

Spontaneous natural killer cell lymphoproliferative disorder in a rhesus macaque.

Lymphoproliferative disorders of natural killer (NK)-cell lineage are well documented in humans but have yet to be documented in non-human primates (NHPs). Here we describe a case of NK-cell lymphoproliferative disorder/leukemia in a 20-y-old captive female rhesus macaque (Macaca mulatta). The animal clinically had mild splenomegaly and marked lymphocytosis with small-to-medium lymphocytes in blood smears. By flow cytometry and cluster differentiation, the lymphocytes were CD3-negative, CD8-positive, CD4-negative, and CD20-negative for cell surface markers; immunohistochemistry revealed the presence of intracellular CD3 and granzyme B. This immunoprofile is consistent with a NK-cell phenotype. Histologically, these cells were predominantly intravascular within the splenic red pulp, liver sinusoids, and to a lesser degree bone marrow. Oncogenic viruses, such as Mason-Pfizer monkey viruses (MPMV; formerly, and commonly known as, simian retroviruses or SRV; Retroviridae, Betaretrovirus maspfimon); simian immunodeficiency virus (SIV; Retroviridae, Lentivirus simimdef), and primate T-lymphotropic virus 1 (PTLV1; commonly known as simian T-lymphotropic virus type 1, STLV1; Retroviridae, Deltaretrovirus priTlym1), were not detected in this animal by serology. Immunohistochemistry using EBNA2 antibody to detect rhesus and cynomolgus monkey lymphocryptovirus (McGHV4/RLV and McGHV10 respectively; Orthoherpesviridae, Lymphocryptovirus macacinegamma4 and Lymphocryptovirus macacinegamma13, respectively) was negative. Together these findings are consistent with a diagnosis of naturally occurring NK-cell lymphoproliferative disorder. NK-cell lymphoproliferative disorder has not been reported previously in rhesus macaques, to our knowledge.

Potent and broad HIV-1 neutralization in fusion peptide-primed SHIV-infected macaques.

An antibody-based HIV-1 vaccine will require the induction of potent cross-reactive HIV-1-neutralizing responses. To demonstrate feasibility toward this goal, we combined vaccination targeting the fusion-peptide site of vulnerability with infection by simian-human immunodeficiency virus (SHIV). In four macaques with vaccine-induced neutralizing responses, SHIV infection boosted plasma neutralization to 45%-77% breadth (geometric mean 50% inhibitory dilution [ID50] ∼100) on a 208-strain panel. Molecular dissection of these responses by antibody isolation and cryo-electron microscopy (cryo-EM) structure determination revealed 15 of 16 antibody lineages with cross-clade neutralization to be directed toward the fusion-peptide site of vulnerability. In each macaque, isolated antibodies from memory B cells recapitulated the plasma-neutralizing response, with fusion-peptide-binding antibodies reaching breadths of 40%-60% (50% inhibitory concentration [IC50]<50μg/mL) and total lineage-concentrations estimates of 50-200μg/mL. Longitudinal mapping indicated that these responses arose prior to SHIV infection. Collectively, these results provide invivo molecular examples for one to a few B cell lineages affording potent, broadly neutralizing plasma responses.

Tissue-Specific DNA Methylation Changes in CD8+ T Cells During Chronic Simian Immunodeficiency Virus Infection of Infant Rhesus Macaques.

Robust CD8+ T cell responses are critical for the control of HIV infection in both adults and children. Our understanding of the mechanisms driving these responses is based largely on studies of cells circulating in peripheral blood in adults, but the regulation of CD8+ T cell responses in tissue sites is poorly understood, particularly in pediatric infections. DNA methylation is an epigenetic modification that regulates gene transcription. Hypermethylated gene promoters are associated with transcriptional silencing and, conversely, hypomethylated promoters indicate gene activation. In this study, we evaluated DNA methylation signatures of CD8+ T cells isolated from several different anatomic compartments during pediatric AIDS-virus infection by utilizing the SIVmac239/251 infected infant rhesus macaque model. We performed a stepwise methylation analysis starting with total cellular DNA, to immunomodulatory cytokine promoters, to specific CpG sites within the cytokine promoters in CD8+ T cells isolated from peripheral blood, lymph nodes, and intestinal tissue during the chronic phase of infection. Tissue-specific methylation patterns were determined for transcriptionally active promoters of key immunomodulatory cytokines: interferon gamma (IFNγ), interleukin-2 (IL-2), and tumor necrosis factor alpha (TNFα). In this study, we observed tissue-specific differences in CD8+ T cell modulation by DNA methylation in SIV-infected infant macaques, highlighting the importance of evaluating cells from both blood and tissues to obtain a complete picture of CD8+ T cell regulation during pediatric HIV infection.

Stem cell transplantation and allogeneic immunity: post treatment control or HIV cure?

Long-lasting HIV remission has been reported in a small group of people with HIV (PWH) following allogenic hematopoietic stem cell transplants (HSCT) for the treatment of hematologic malignancies. While the mechanisms of HIV remission following release from antiretroviral therapy (ART) were not initially known, subsequent findings from clinical cases and preclinical nonhuman primate studies have implicated mechanisms of clearance. Here, we review the six currently published human cases of long-term ART-free HIV remission. Since the first report of ART-free HIV remission following HSCT, five subsequent cases of HSCT-induced sustained HIV remission have been published. While the pre- and posttransplant treatment conditions vary greatly, all but one received cells from donors homozygous for a 32 bp deletion in the gene that encodes CCR5 ( ccr5Δ32 ), the major HIV coreceptor. Studies in nonhuman primates and the newest published individual suggest that while CCR5 deficiency can protect donor cells from infection early posttransplant, it is not required for long term remission, as ablation of the viral reservoir is likely due to allogeneic immunity mediating a graft-versus-reservoir response. Studies of HSCT in PLWH and simian immunodeficiency virus (SIV)-infected monkeys show that those with durable remission are likely cured, demonstrated by complete ablation of the replication-competent HIV reservoir, gradual loss of anti-HIV immunity, and greater than 5 years of aviremia.

Self-replicating recombinant virus-like particles of lentivirus proliferating in glioblastoma cells and normal human macrophages

Introduction. Both attenuated and inactivated vaccines are used in disease control. Inactivated vaccines are very diverse and include whole cell and acellular vaccines containing protein target antigens or nucleic acids encoding target antigens. Immunity induced by inactivated vaccines is not believed to be long-lasting. It is very problematic to develop a vaccine against viruses that integrate into the genome of the host cell, as well as against persistent viruses that penetrate the central nervous system (CNS), which is typical for the human immunodeficiency virus type 1 (HIV-1). Aim of the study: to evaluate the possibility of forming HIV-1 recombinant virus-like particles (recVLPs) and HIV-1B recombinant VLPs and simian immunodeficiency virus (SIV) — SHIV89.6P based on self-replicating RNAs (srRNAs) producing target lentivirus antigens on the alphavirus replicon platform (Sindbis virus or Venezuelan equine encephalomyelitis virus (VEEV)), and also to evaluate the ability of HIV-1B and SHIV89.6P VLPs to infect glioblastoma cells and normal human macrophages. Materials and methods. BHK-21 cells were transfected with the srRNA mixture by electroporation. Recombinant virus-like particles (recVLP’s) in recVLP’s-infected cells were detected using the immunofluorescence assay (ELISA) and electron microscopy. recVLP’s were used to infect glioblastoma cells and normal macrophages from a healthy donor. Results. Based on the genomic RNA of the alphavirus, the plasmids were created, transcription from which makes it possible to obtain RNA that expresses lentiviral gene products in cells in quantities sufficient for the formation of mature VLPs. In BHK-21 cells infected with recVLP’s, virus-specific antigens are detected only in the cytoplasm, but not in the nucleus. Both glioblastoma cells (U87) and normal human macrophages containing CD4 receptor and SSR5 and CXR4 co-receptors give infectious progeny of HIV-1B and SHIV89.6P recVLP’s when infected with supernatant obtained after transfection of BHK-21 cells with srRNA. Discussion. The results obtained show the possibility of expressing lentivirus structural proteins in glioblastoma cells (U87) and in normal human macrophages and can be used in the future to study the presentation of antigens in native and functional conformations in appropriate model systems to study the possibility of suppressing HIV infection in viral reservoirs in the CNS.