Simian Immunodeficiency Virus Research Articles

IFI27 inhibits HIV-1 replication by degrading Gag protein through the ubiquitin-proteasome pathway.

Type I interferon (IFN-I) and its downstream genes play a profound role in HIV infection. In this study, we found that an IFN-inducible gene, IFI27, was upregulated in HIV-1 infection, which in turn efficiently suppressed HIV-1 replication, specially degraded the viral gag protein, including p24 and p55 subunits. Notably, the anti-HIV-1 activity of IFI27 in Old World monkeys surpassed that in New World monkeys, and IFI27 has a higher potentially inhibitory effect on HIV-1 than simian immunodeficiency virus (SIV). Our initial observations showed that NPM-IFI27, the IFI27 variant in northern pig-tailed macaque (Macaca leonina, NPM), exhibited a strong anti-HIV-1 activity. Further investigation demonstrated that NPM-IFI27 degraded p24 and p55 via the ubiquitin-proteasome pathway, with NPM-IFI27-37-115 interacting with the p24-N domain, and the NPM-IFI27-76-122 domain was closely associated with K48 ubiquitin recruitment. Additionally, Skp2 was identified as the probable E3 ubiquitin ligase responsible for the degradation of p24 and p55. Similarly, human IFI27 (Hu-IFI27) showed a mechanism similar to NPM-IFI27 in HIV-1 inhibition. These findings underscore the pivotal role of NPM-IFI27 in HIV-1 infection and provide a potential strategy for clinical anti-HIV-1 therapy.IMPORTANCEHIV-1 infection can trigger the production of IFN-I, which subsequently activates the expression of various IFN-stimulated genes (ISGs) to antagonize the virus. Therefore, discovering novel host antiviral agents for HIV-1 treatment is crucial. Our previous study revealed that IFI27 can influence HIV-1 replication. In this study, we observed that the NPM-IFI27 complex specifically inhibited HIV-1 by targeting its Gag protein. Further exploration demonstrated that IFI27 interacted with the HIV-1 p24 and p55 proteins, leading to their degradation through the ubiquitin-proteasome pathway. Notably, the NPM-IFI27-37-122 variant exhibited potent anti-HIV-1 activity, comparable to that of SAMHD1. These findings highlight the critical role and inhibitory mechanism of NPM-IFI27 in HIV-1 infection, providing a potential strategy for clinical antiviral therapy.

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.

Minimally Modified HIV-1 Infection of Macaques: Development, Utility, and Limitations of Current Models.

Nonhuman primate (NHP) studies that utilize simian immunodeficiency virus (SIV) to model human immunodeficiency virus (HIV-1) infection have proven to be powerful, highly informative research tools. However, there are substantial differences between SIV and HIV-1. Accordingly, there are numerous research questions for which SIV-based models are not well suited, including studies of certain aspects of basic HIV-1 biology, and pre-clinical evaluations of many proposed HIV-1 treatment, prevention, and vaccination strategies. To overcome these limitations of NHP models of HIV-1 infection, several groups have pursued the derivation of a minimally modified HIV-1 (mmHIV-1) capable of establishing pathogenic infection in macaques that authentically recapitulates key features of HIV-1 in humans. These efforts have focused on three complementary objectives: (1) engineering HIV-1 to circumvent species-specific cellular restriction factors that otherwise potently inhibit HIV-1 in macaques, (2) introduction of a C chemokine receptor type 5 (CCR5)-tropic envelope, ideally that can efficiently engage macaque CD4, and (3) correction of gene expression defects inadvertently introduced during viral genome manipulations. While some progress has been made toward development of mmHIV-1 variants for use in each of the three macaque species (pigtail, cynomolgus, and rhesus), model development progress has been most promising in pigtail macaques (PTMs), which do not express an HIV-1-restricting tripartite motif-containing protein 5 α (TRIM5α). In our work, we have derived a CCR5-tropic mmHIV-1 clone designated stHIV-A19 that comprises 94% HIV-1 genome sequence and replicates to high acute-phase titers in PTMs. In animals treated with a cell-depleting CD8α antibody at the time of infection, stHIV-A19 maintains chronically elevated plasma viral loads with progressive CD4+ T-cell loss and the development of acquired immune-deficiency syndrome (AIDS)-defining clinical endpoints. However, in the absence of CD8α+ cell depletion, no mmHIV-1 model has yet displayed high levels of chronic viremia or AIDS-like pathogenesis. Here, we review mmHIV-1 development approaches, the phenotypes, features, limitations, and potential utility of currently available mmHIV-1s, and propose future directions to further advance these models.

Functional genomic analysis of the 68-1 RhCMV-Mycobacteria tuberculosis vaccine reveals an IL-15 response signature that is conserved with vector attenuation.

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb) is a deadly infectious disease having a major impact on global health. Using the CMV vector for development of novel vaccines is a promising new strategy that elicits strong and durable, high frequency memory T cell responses against heterologous immunogens. We conducted functional transcriptomic analysis of whole blood samples collected from cohorts of rhesus (Rh) macaques that were administered RhCMV/TB vector using a prime-boost strategy. Two modified CMV vectors were used in this study, including 68-1 RhCMV/TB-6Ag (encoding 6 Mtb protein immunogens, including Ag85A, ESAT-6, Rv3407, Rv2626, Rpf A, and Rpf D) and its attenuated variant, 68-1 RhCMV/Δpp71-TB-6Ag (a cell-to-cell spread-deficient vaccine vector lacking the Rh110 gene encoding the pp71 tegument protein). Bulk mRNA sequencing, differential gene expression, and functional enrichment analyses showed that these RhCMV/TB vaccines induce the innate and adaptive immune responses with specific transcriptomic signatures, including the IL-15-induced protective gene signature previously defined to be linked with protection against simian immunodeficiency virus (SIV) by the 68-1 RhCMV/SIV vaccine. While both vectors exhibited a transcriptomic response of the IL-15 protective signature in whole blood, we show that lack of pp71 does not maintain induction of the protective signature for the full duration of the study compared to the parental non-attenuated vector. Our observations indicate that RhCMV vector vaccines induce a transcriptomic response in whole blood that include a conserved IL-15 signature of which vector-encoded pp71 is an important component of response durability that upon future Mtb challenge may define specific vaccine protection outcomes against Mtb infection.

Double-Negative T-Cells during Acute Human Immunodeficiency Virus and Simian Immunodeficiency Virus Infections and Following Early Antiretroviral Therapy Initiation.

HIV infection significantly affects the frequencies and functions of immunoregulatory CD3+CD4-CD8- double-negative (DN) T-cells, while the effect of early antiretroviral therapy (ART) initiation on these cells remains understudied. DN T-cell subsets were analyzed prospectively in 10 HIV+ individuals during acute infection and following early ART initiation compared to 20 HIV-uninfected controls. In this study, 21 Rhesus macaques (RMs) were SIV-infected, of which 13 were assessed during acute infection and 8 following ART initiation four days post-infection. DN T-cells and FoxP3+ DN Treg frequencies increased during acute HIV infection, which was not restored by ART. The expression of activation (HLA-DR/CD38), immune checkpoints (PD-1/CTLA-4), and senescence (CD28-CD57+) markers by DN T-cells and DN Tregs increased during acute infection and was not normalized by ART. In SIV-infected RMs, DN T-cells remained unchanged despite infection or ART, whereas DN Treg frequencies increased during acute SIV infection and were not restored by ART. Finally, frequencies of CD39+ DN Tregs increased during acute HIV and SIV infections and remained elevated despite ART. Altogether, acute HIV/SIV infections significantly changed DN T-cell and DN Treg frequencies and altered their immune phenotype, while these changes were not fully normalized by early ART, suggesting persistent HIV/SIV-induced immune dysregulation despite early ART initiation.

Structures of the Foamy virus fusion protein reveal an unexpected link with the F protein of paramyxo- and pneumoviruses.

Foamy viruses (FVs) constitute a subfamily of retroviruses. Their envelope (Env) glycoprotein drives the merger of viral and cellular membranes during entry into cells. The only available structures of retroviral Envs are those from human and simian immunodeficiency viruses from the subfamily of orthoretroviruses, which are only distantly related to the FVs. We report the cryo-electron microscopy structures of the FV Env ectodomain in the pre- and post-fusion states, which unexpectedly demonstrate structural similarity with the fusion protein (F) of paramyxo- and pneumoviruses, implying an evolutionary link between the viral fusogens. We describe the structural features that are unique to the FV Env and propose a mechanistic model for its conformational change, highlighting how the interplay of its structural elements could drive membrane fusion and viral entry. The structural knowledge on the FV Env now provides a framework for functional investigations, which can benefit the design of FV Env variants with improved features for use as gene therapy vectors.

Human cytomegalovirus UL18 prevents priming of MHC-E- and MHC-II-restricted CD8+ T cells.

Rhesus cytomegalovirus (RhCMV) vectors elicit major histocompatibility complex (MHC)-E-restricted CD8+ T cells that stringently control simian immunodeficiency virus (SIV) in rhesus macaques. These responses require deletion of eight RhCMV chemokine-like open reading frames (ORFs) that are conserved in human cytomegalovirus (HCMV). To determine whether HCMV encodes additional, nonconserved inhibitors of unconventional T cell priming, we inserted 41 HCMV-specific ORFs into a chemokine-deficient strain (68-1 RhCMV). Monitoring of epitope recognition revealed that HCMV UL18 prevented unconventional T cell priming, resulting in MHC-Ia-targeted responses. UL18 is homologous to MHC-I but does not engage T cell receptors and, instead, binds with high affinity to inhibitory leukocyte immunoglobulin-like receptor-1 (LIR-1). UL18 lacking LIR-1 binding no longer interfered with MHC-E-restricted T cell stimulation by RhCMV-infected cells or the induction of unconventionally restricted T cells. Thus, LIR-1 binding needs to be deleted from UL18 of HCMV/HIV vaccines to allow for the induction of protective MHC-E-restricted T cells.

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.

Host genetic and immune factors drive evasion of HIV-1 pathogenesis in viremic non-progressors.

Viremic non-progressors (VNPs) represent an exceptional and uncommon subset of people with HIV-1, characterized by the remarkable preservation of normal CD4+ Tcell counts despite uncontrolled viral replication-a trait reminiscent of natural hosts of simian immunodeficiency virus. The mechanisms orchestrating evasion from HIV-1 pathogenesis in human VNPs remain elusive, primarily due to the absence of integrative studies. We implemented a novel single-cell and multiomics approach to comprehensively characterize viral, genomic, transcriptomic, and metabolomic factors driving this exceedingly rare disease phenotype in 16 VNPs and 29 HIV+ progressors. Genetic predisposition to the VNP phenotype was evidenced by a higher prevalence of CCR5Δ32 heterozygosity, which was associated with lower levels of CCR5 expression and a lower frequency of infected cells in peripheral circulation. We also observed reduced levels of plasma markers of intestinal disruption and attenuated interferon responses in VNPs. These factors potentially drive the other phenotypic traits of immune preservation in this population, including the unaltered tryptophan metabolic profile, reduced activation of cytotoxic lymphocytes, and reduced bystander CD4+ Tcell apoptosis. In summary, our comprehensive analysis identified intricate factors collectively associated with the unique immunovirological equilibrium in VNPs, shedding light on potential avenues for therapeutic exploration in managing HIV pathogenesis. The work was supported by funding from the Spanish Ministry of Science and Innovation and the National Institutes of Health (NIH).

High fat, high sucrose diet promotes increased expression of ACE2 receptor in the SIV-infected host: implications for SARS-CoV-2 infection.

People with pre-existing conditions, including metabolic comorbidities, are at greater risk for complications of SARS-CoV-2 infection and expression of machinery required for viral entry into host cells may be a contributing factor. This study tested the hypothesis that high fat, high sucrose diet (HFSD) and alcohol use increase expression of angiotensin converting enzyme 2 (ACE2) receptor and transmembrane serine protease 2 (TMPRSS2) in tissues isolated from simian immunodeficiency virus (SIV) infected macaques, the most clinically relevant model for the study of HIV. Biospecimens obtained from a longitudinal study of SIV-infected, antiretroviral therapy (ART)-treated female rhesus macaques (Macaca mulatta) were used to determine whether HFSD and chronic binge alcohol (CBA) increased ACE2 and TMPRSS2 protein and gene expression. Macaques (n = 10) were assigned to HFSD or standard diet (SD) for 3 months before CBA or vehicle administration. Three months later, macaques were infected with SIV; ART was initiated 2.5 months thereafter. Tissue samples including lung, pancreas, and kidney were collected at study endpoint (12 months post-SIV infection). Protein expression of ACE2 in the lung, whole pancreas, and pancreatic islets was significantly greater in HFSD- than SD-fed macaques with no significant differences in protein expression of TMPRSS2 or mRNA expression of ACE2 or TMPRSS2. CBA did not significantly alter any measures. The increased ACE2 receptor expression observed in lung and pancreas of SIV-infected HFSD-fed female rhesus macaques aligns with reports that diet may increase susceptibility to COVID-19. These data provide direct evidence for a link between dietary quality and cellular adaptations that may increase the risk for SARS-CoV-2 infection.

Pre-challenge gut microbial signature predicts RhCMV/SIV vaccine efficacy in rhesus macaques.

Rhesus cytomegalovirus expressing simian immunodeficiency virus (RhCMV/SIV) vaccines protect ~59% of vaccinated rhesus macaques against repeated limiting-dose intra-rectal exposure with highly pathogenic SIVmac239M, but the exact mechanism responsible for the vaccine efficacy is unknown. It is becoming evident that complex interactions exist between gut microbiota and the host immune system. Here, we aimed to investigate if the rhesus gut microbiome impacts RhCMV/SIV vaccine-induced protection. Three groups of 15 rhesus macaques naturally pre-exposed to RhCMV were vaccinated with RhCMV/SIV vaccines. Rectal swabs were collected longitudinally both before SIV challenge (after vaccination) and post-challenge and were profiled using 16S rRNA based microbiome analysis. We identified ~2,400 16S rRNA amplicon sequence variants (ASVs), representing potential bacterial species/strains. Global gut microbial profiles were strongly associated with each of the three vaccination groups, and all animals tended to maintain consistent profiles throughout the pre-challenge phase. Despite vaccination group differences, by using newly developed compositional data analysis techniques, we identified a common gut microbial signature predictive of vaccine protection outcome across the three vaccination groups. Part of this microbial signature persisted even after SIV challenge. We also observed a strong correlation between this microbial signature and an early signature derived from whole blood transcriptomes in the same animals. Our findings indicate that changes in gut microbiomes are associated with RhCMV/SIV vaccine-induced protection and early host response to vaccination in rhesus macaques.IMPORTANCEThe human immunodeficiency virus (HIV) has infected millions of people worldwide. Unfortunately, still there is no vaccine that can prevent or treat HIV infection. A promising pre-clinical HIV vaccine based on rhesus cytomegalovirus (RhCMV) expressing simian immunodeficiency virus (SIV) antigens (RhCMV/SIV) provides sustained, durable protection against SIV challenge in ~59% of vaccinated rhesus macaques. There is an urgent need to understand the cause of this protection vs non-protection outcome. In this study, we profiled the gut microbiomes of 45 RhCMV/SIV vaccinated rhesus macaques and identified gut microbial signatures that were predictive of RhCMV/SIV vaccination groups and vaccine protection outcomes. These vaccine protection-associated microbial features were significantly correlated with early vaccine-induced host immune signatures in whole blood from the same animals. These findings show that the gut microbiome may be involved in RhCMV/SIV vaccine-induced protection, warranting further research into the impact of the gut microbiome in human vaccine trials.

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 performed 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 found that the myeloid cell populations were significantly changed by SIVE. 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 was found in which the chromatin accessibility of genes diverged from their RNA expression. Additionally, we observed a dramatic shift of upstream gene regulators and their targets in brain myeloid cells during SIVE. In summary, this study further uncovers the transcriptome, gene regulatory events and potential roles of different brain myeloid phenotypes in SIVE.

Regulation of the cell surface expression of classical and non-classical MHC proteins by the human cytomegalovirus UL40 and rhesus cytomegalovirus Rh67 proteins.

The protective immune response induced by a rhesus cytomegalovirus (RhCMV)-vectored simian immunodeficiency virus (SIV) vaccine in rhesus macaques depends on the presence of the viral Rh67 gene in the vaccine. The Rh67 protein contains a peptide that allows the RhCMV-infected cells to maintain expression of major histocompatibility complex (MHC) antigen E at the cell surface. We show that production of this peptide, referred to as "VL9," mirrors that of the equivalent peptide present in the human cytomegalovirus (CMV) protein UL40, despite the little sequence similarity between the two CMV proteins. We also show that the mature UL40 and Rh67 proteins, which have no previously described function, also contribute to CMV immune evasion by reducing cell surface expression of MHC proteins important for the immune system to detect infected cells. Despite these similarities, our work also reveals possible differences between Rh67 and UL40, and these may have implications for the use of human CMV as the vector for a potential HIV-1 vaccine.

Microglia and macrophages alterations in the CNS during acute SIV infection: A single-cell analysis in rhesus macaques.

Human Immunodeficiency Virus (HIV) is widely acknowledged for its profound impact on the immune system. Although HIV primarily affects peripheral CD4 T cells, its influence on the central nervous system (CNS) cannot be overlooked. Within the brain, microglia and CNS-associated macrophages (CAMs) serve as the primary targets for HIV and the simian immunodeficiency virus (SIV) in nonhuman primates. This infection can lead to neurological effects and establish a viral reservoir. Given the gaps in our understanding of how these cells respond in vivo to acute CNS infection, we conducted single-cell RNA sequencing (scRNA-seq) on myeloid cells from the brains of three rhesus macaques 12 days after SIV infection, along with three uninfected controls. Our analysis revealed six distinct microglial clusters including homeostatic microglia, preactivated microglia, and activated microglia expressing high levels of inflammatory and disease-related molecules. In response to acute SIV infection, the homeostatic and preactivated microglia population decreased, while the activated and disease-related microglia increased. All microglial clusters exhibited upregulation of MHC class I molecules and interferon-related genes, indicating their crucial roles in defending against SIV during the acute phase. All microglia clusters also upregulated genes linked to cellular senescence. Additionally, we identified two distinct CAM populations: CD14lowCD16hi and CD14hiCD16low CAMs. Interestingly, during acute SIV infection, the dominant CAM population changed to one with an inflammatory phenotype. Specific upregulated genes within one microglia and one macrophage cluster were associated with neurodegenerative pathways, suggesting potential links to neurocognitive disorders. This research sheds light on the intricate interactions between viral infection, innate immune responses, and the CNS, providing valuable insights for future investigations.

Dual blockade of IL-10 and PD-1 leads to control of SIV viral rebound following analytical treatment interruption

Human immunodeficiency virus (HIV) persistence during antiretroviral therapy (ART) is associated with heightened plasma interleukin-10 (IL-10) levels and PD-1 expression. We hypothesized that IL-10 and PD-1 blockade would lead to control of viral rebound following analytical treatment interruption (ATI). Twenty-eight ART-treated, simian immunodeficiency virus (SIV)mac239-infected rhesus macaques (RMs) were treated with anti-IL-10, anti-IL-10 plus anti-PD-1 (combo) or vehicle. ART was interrupted 12 weeks after introduction of immunotherapy. Durable control of viral rebound was observed in nine out of ten combo-treated RMs for >24 weeks post-ATI. Induction of inflammatory cytokines, proliferation of effector CD8+ T cells in lymph nodes and reduced expression of BCL-2 in CD4+ T cells pre-ATI predicted control of viral rebound. Twenty-four weeks post-ATI, lower viral load was associated with higher frequencies of memory T cells expressing TCF-1 and of SIV-specific CD4+ and CD8+ T cells in blood and lymph nodes of combo-treated RMs. These results map a path to achieve long-lasting control of HIV and/or SIV following discontinuation of ART.

Immunization of cows with HIV envelope trimers generates broadly neutralizing antibodies to the V2-apex from the ultralong CDRH3 repertoire.

The generation of broadly neutralizing antibodies (bnAbs) to conserved epitopes on HIV Envelope (Env) is one of the cornerstones of HIV vaccine research. The animal models commonly used for HIV do not reliably produce a potent broadly neutralizing serum antibody response, with the exception of cows. Cows have previously produced a CD4 binding site response by homologous prime and boosting with a native-like Env trimer. In small animal models, other engineered immunogens were shown to focus antibody responses to the bnAb V2-apex region of Env. Here, we immunized two groups of cows (n = 4) with two regimens of V2-apex focusing Env immunogens to investigate whether antibody responses could be generated to the V2-apex on Env. Group 1 was immunized with chimpanzee simian immunodeficiency virus (SIV)-Env trimer that shares its V2-apex with HIV, followed by immunization with C108, a V2-apex focusing immunogen, and finally boosted with a cross-clade native-like trimer cocktail. Group 2 was immunized with HIV C108 Env trimer followed by the same HIV trimer cocktail as Group 1. Longitudinal serum analysis showed that one cow in each group developed serum neutralizing antibody responses to the V2-apex. Eight and 11 bnAbs were isolated from Group 1 and Group 2 cows, respectively, and showed moderate breadth and potency. Potent and broad responses in this study developed much later than previous cow immunizations that elicited CD4bs bnAbs responses and required several different immunogens. All isolated bnAbs were derived from the ultralong CDRH3 repertoire. The finding that cow antibodies can target more than one broadly neutralizing epitope on the HIV surface reveals the generality of elongated structures for the recognition of highly glycosylated proteins. The exclusive isolation of ultralong CDRH3 bnAbs, despite only comprising a small percent of the cow repertoire, suggests these antibodies outcompete the long and short CDRH3 antibodies during the bnAb response.

Characterization of the gut butyrate-producing bacteria and lipid metabolism in African green monkey as a natural host of simian immunodeficiency virus infection.

Natural hosts of simian immunodeficiency virus (SIV), such as the African green monkey (AGM), possess the ability to avoid acquired immune deficiency syndrome (AIDS) despite lifelong infection. The underlying mechanisms are not completely understood. This study aimed to characterize the gut microbiome and metabolite profiles of different nonhuman primates (NHPs) to provide potential insight into AIDS resistance. Fresh feces from Cynomolgus macaques (CMs), and Rhesus macaques (RMs), SIV- AGMs (AGM_N), and SIV+ AGMs (AGM_P) were collected and used for metagenomic sequencing and metabonomic analysis. Compared with CMs and RMs, significant decreases in the abundances of Streptococcus , Alistipes , Treponema , Bacteroides , and Methanobrevibacter ( P < 0.01), and significant increases in the abundances of Clostridium , Eubacterium , Blautia , Roseburia , Faecalibacterium , and Dialister ( P < 0.01) were detected in AGM_N. Compared with AGM_N, a trend toward increased abundances of Streptococcus and Roseburia were found in AGM_P. The levels of metabolites involved in lipid metabolism and butanoate metabolism significantly differed among AGM_P, AGM_N and CM ( P < 0.05). Our data, for the first time, demonstrated distinguishing features in the abundances of butyrate-producing bacteria and lipid metabolism capacities between different NHP hosts of SIV infection. These findings may correlate with the different characteristics observed among these hosts in the maintenance of intestinal epithelial barrier integrity, regulation of inflammation, and provide insights into AIDS resistance in AGMs.

Administration of anti-HIV-1 broadly neutralizing monoclonal antibodies with increased affinity to Fcγ receptors during acute SHIVAD8-EO infection

Anti-HIV-1 broadly neutralizing antibodies (bNAbs) have the dual potential of mediating virus neutralization and antiviral effector functions through their Fab and Fc domains, respectively. So far, bNAbs with enhanced Fc effector functions in vitro have only been tested in NHPs during chronic simian-HIV (SHIV) infection. Here, we investigate the effects of administering in acute SHIVAD8-EO infection either wild-type (WT) bNAbs or bNAbs carrying the S239D/I332E/A330L (DEL) mutation, which increases binding to FcγRs. Emergence of virus in plasma and lymph nodes (LNs) was delayed by bNAb treatment and occurred earlier in monkeys given DEL bNAbs than in those given WT bNAbs, consistent with faster clearance of DEL bNAbs from plasma. DEL bNAb-treated monkeys had higher levels of circulating virus-specific IFNγ single-producing CD8+ CD69+ T cells than the other groups. In LNs, WT bNAbs were evenly distributed between follicular and extrafollicular areas, but DEL bNAbs predominated in the latter. At week 8 post-challenge, LN monocytes and NK cells from DEL bNAb-treated monkeys upregulated proinflammatory signaling pathways and LN T cells downregulated TNF signaling via NF-κB. Overall, bNAbs with increased affinity to FcγRs shape innate and adaptive cellular immunity, which may be important to consider in future strategies of passive bNAb therapy.

Concurrent TB and HIV therapies effectively control clinical reactivation of TB during co-infection but fail to eliminate chronic immune activation.

The majority of Human Immunodeficiency Virus (HIV) negative individuals exposed to Mycobacterium tuberculosis (Mtb) control the bacillary infection as latent TB infection (LTBI). Co-infection with HIV, however, drastically increases the risk to progression to tuberculosis (TB) disease. TB is therefore the leading cause of death in people living with HIV (PLWH) globally. Combinatorial antiretroviral therapy (cART) is the cornerstone of HIV care in humans and reduces the risk of reactivation of LTBI. However, the immune control of Mtb infection is not fully restored by cART as indicated by higher incidence of TB in PLWH despite cART. In the macaque model of co-infection, skewed pulmonary CD4+ TEM responses persist, and new TB lesions form despite cART treatment. We hypothesized that regimens that concurrently administer anti-TB therapy and cART would significantly reduce TB in co-infected macaques than cART alone, resulting in superior bacterial control, mitigation of persistent inflammation and lasting protective immunity. We studied components of TB immunity that remain impaired after cART in the lung compartment, versus those that are restored by concurrent 3 months of once weekly isoniazid and rifapentine (3HP) and cART in the rhesus macaque (RM) model of LTBI and Simian Immunodeficiency Virus (SIV) co-infection. Concurrent administration of cART + 3HP did improve clinical and microbiological attributes of Mtb/SIV co-infection compared to cART-naïve or -untreated RMs. While RMs in the cART + 3HP group exhibited significantly lower granuloma volumes after treatment, they, however, continued to harbor caseous granulomas with increased FDG uptake. cART only partially restores the constitution of CD4 + T cells to the lung compartment in co-infected macaques. Concurrent therapy did not further enhance the frequency of reconstituted CD4+ T cells in BAL and lung of Mtb/SIV co-infected RMs compared to cART, and treated animals continued to display incomplete reconstitution to the lung. Furthermore, the reconstituted CD4+ T cells in BAL and lung of cART + 3HP treated RMs exhibited an increased frequencies of activated, exhausted and inflamed phenotype compared to LTBI RMs. cART + 3HP failed to restore the effector memory CD4+ T cell population that was significantly reduced in pulmonary compartment post SIV co-infection. Concurrent therapy was associated with the induction of Type I IFN transcriptional signatures and led to increased Mtb-specific TH1/TH17 responses correlated with protection, but decreased Mtb-specific TNFa responses, which could have a detrimental impact on long term protection. Our results suggest the mechanisms by which Mtb/HIV co-infected individuals remain at risk for progression due to subsequent infections or reactivation due of persisting defects in pulmonary T cell responses. By identifying lung-specific immune components in this model, it is possible to pinpoint the pathways that can be targeted for host-directed adjunctive therapies for TB/HIV co-infection.

A heterocyclic compound inhibits viral release by inducing cell surface BST2/Tetherin/CD317/HM1.24

The introduction of combined antiretroviral therapy (cART) has greatly improved the quality of life of human immunodeficiency virus type 1 (HIV-1)-infected individuals. Nonetheless, the ever-present desire to seek out a full remedy for HIV-1 infections makes the discovery of novel antiviral medication compelling. Owing to this, a new late-stage inhibitor, Lenacapavir/Sunlenca, an HIV multi-phase suppressor, was clinically authorized in 2022. Besides unveiling cutting-edge antivirals inhibiting late-stage proteins or processes, newer therapeutics targeting host restriction factors hold promise for the curative care of HIV-1 infections. Notwithstanding, bone marrow stromal antigen 2 (BST2)/Tetherin/CD317/HM1.24, which entraps progeny virions is an appealing HIV-1 therapeutic candidate. In this study, a novel drug screening system was established, using the Jurkat/Vpr-HiBiT T cells, to identify drugs that could obstruct HIV-1 release; the candidate compounds were selected from the Ono Pharmaceutical compound library. Jurkat T cells expressing Vpr-HiBiT were infected with NL4-3, and the amount of virus release was quantified indirectly by the amount of Vpr-HiBiT incorporated into the progeny virions. Subsequently, the candidate compounds that suppressed viral release were used to synthesize the heterocyclic compound, HT-7, which reduces HIV-1 release with less cellular toxicity. Notably, HT-7 increased cell surface BST2 coupled with HIV-1 release reduction in Jurkat cells but not Jurkat/KO-BST2 cells. Seemingly, HT-7 impeded simian immunodeficiency virus (SIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) release. Concisely, these results suggest that the reduction in viral release, following HT-7 treatment, resulted from the modulation of cell surface expression of BST2 by HT-7.