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Inflammatory mediators and viral products produced by human immunodeficiency virus (HIV)-infected microglia and astrocytes perturb the function and viability of adjacent uninfected neuronal and glial cells and contribute to the pathogenesis of HIV-associated neurocognitive disorders (HAND). In vivo exposure to lipopolysaccharide (LPS) activates parenchymal microglia and astrocytes and induces cytokine and chemokine production in the brain. HIV-infected individuals display increased circulating LPS levels due to microbial translocation across a compromised mucosa barrier. We hypothesized that HIV-infected microglia and astrocytes display increased sensitivity to the proinflammatory effects of LPS, and this combines with the increased levels of systemic LPS in HIV-infected individuals to contribute to the development of HAND. To examine this possibility, we determined the in vivo responsiveness of HIV-infected microglia and astrocytes to LPS using our mouse model, JR-CSF/human cyclin T1 (JR-CSF/hu-cycT1) mice, which are transgenic for both an integrated full-length infectious HIV type 1 (HIV-1) provirus derived from the primary R5-tropic clinical isolate HIV-1JR-CSF regulated by the endogenous HIV-1 long terminal repeat and the hu-cycT1 gene under the control of a CD4 promoter. In the current report, we demonstrated that in vivo-administered LPS more potently activated JR-CSF/hu-cycT1 mouse microglia and astrocytes and induced a significantly higher degree of monocyte chemoattractant protein production by JR-CSF/hu-cycT1 astrocytes compared to that of the in vivo LPS response of control littermate mouse microglia and astrocytes. These results indicate that HIV infection increases the sensitivity of microglia and astrocytes to inflammatory stimulation and support the use of these mice as a model to investigate various aspects of the in vivo mechanism of HIV-induced neuronal dysfunction. [ABSTRACT FROM AUTHOR]

Curing HIV infection has been thwarted by the persistent reservoir of latently infected CD4+ T cells, which reinitiate systemic infection after antiretroviral therapy (ART) interruption. To evaluate reservoir depletion strategies, we developed a novel preclinical in vivo model consisting of immunodeficient mice intrasplenically injected with peripheral blood mononuclear cells (PBMC) from long-term ART-suppressed HIV-infected donors. In the absence of ART, these mice developed rebound viremia which, 2 weeks after PBMC injection, was 1,000-fold higher (mean=9,229,281 HIV copies/ml) in mice injected intrasplenically than in mice injected intraperitoneally (mean=6,838 HIV copies/ml) or intravenously (mean=591 HIV copies/ml). One week after intrasplenic PBMC injection, in situ hybridization of the spleen demonstrated extensive disseminated HIV infection, likely initiated from in vivo-reactivated primary latently infected cells. The time to viremia was delayed significantly by treatment with a broadly neutralizing antibody, 10-1074, compared to treatment with 10-1074-FcRnull, suggesting that 10-1074 mobilized Fc-mediated effector mechanisms to deplete the replication-competent reservoir. This was supported by phylogenetic analysis of Env sequences from viral-outgrowth cultures and untreated, 10-1074-treated, or 10-1074-FcRnull-treated mice. The predominant sequence cluster detected in viral-outgrowth cultures and untreated mouse plasma was significantly reduced in the plasma of 10-1074-treated mice, whereas two new clusters emerged that were not detected in viral-outgrowth cultures or plasma from untreated mice. These new clusters lacked mutations associated with 10-1074 resistance. Taken together, these data indicated that 10-1074 treatment depletes the reservoir of latently infected cells harboring replication competent HIV. Furthermore, this mouse model represents a new in vivo approach for the preclinical evaluation of new HIV cure strategies. [ABSTRACT FROM AUTHOR]

The glycan loop of Zika virus (ZIKV) envelope protein (E) contains the glycosylation site and has been well documented to be important for viral pathogenesis and transmission. In the present study, we report that deletions in the E glycan loop, which were recorded in African ZIKV strains previously, have re-emerged in their contemporary Asian lineages. Here, we generated recombinant ZIKV containing specific deletions in the E glycan loop by reverse genetics. Extensive in vitro and in vivo characterization of these deletion mutants demonstrated an attenuated phenotype in an adult A129 mouse model and reduced oral infections in mosquitoes. Surprisingly, these glycan loop deletion mutants exhibited an enhanced neurovirulence phenotype, and resulted in a more severe microcephalic brain in neonatal mouse models. Crystal structures of the ZIKV E protein and a deletion mutant at 2.5 and 2.6 Å, respectively, revealed that deletion of the glycan loop induces encephalitic flavivirus-like conformational alterations, including the appearance of perforations on the surface and a clear change in the topology of the loops. Overall, our results demonstrate that the E glycan loop deletions represent neonatal mouse neurovirulence markers of ZIKV. IMPORTANCE Zika virus (ZIKV) has been identified as a cause of microcephaly and acquired evolutionary mutations since its discovery. Previously deletions in the E glycan loop were recorded in African ZIKV strains, which have re-emerged in the contemporary Asian lineages recently. The glycan loop deletion mutants are not glycosylated, which are attenuated in adult A129 mouse model and reduced oral infections in mosquitoes. More importantly, the glycan loop deletion mutants induce an encephalitic flavivirus-like conformational alteration in the E homodimer, resulting in a significant enhancement of neonatal mouse neurovirulence. This study underscores the critical role of glycan loop deletion mutants in ZIKV pathogenesis, highlighting a need for global virological surveillance for such ZIKV variants. [ABSTRACT FROM AUTHOR]

Due to the inherent immune evasion properties of the HIV envelope, broadly neutralizing HIV-specific antibodies capable of suppressing HIV infection are rarely produced by infected individuals. We examined the feasibility of utilizing genetic engineering to circumvent the restricted capacity of individuals to endogenously produce broadly neutralizing HIV-specific antibodies. We constructed a single lentiviral vector that encoded the heavy and light chains of 2G12, a broadly neutralizing anti-HIV human antibody, and that efficiently transduced and directed primary human B cells to secrete 2G12. To evaluate the capacity of this approach to provide protection from in vivo HIV infection, we used the humanized NOD/SCID/ γcnull mouse model, which becomes populated with human B cells, T cells, and macrophages after transplantation with human hematopoietic stem cells (hu-HSC) and develops in vivo infection after inoculation with HIV. The plasma of the irradiated NOD/SCID/ γcnull mice transplanted with hu-HSC transduced with the 2G12-encoding lentivirus contained 2G12 antibody, likely secreted by progeny human lymphoid and/or myeloid cells. After intraperitoneal inoculation with high-titer HIV-1JR-CSF, mice engrafted with 2G12-transduced hu-HSC displayed marked inhibition of in vivo HIV infection as manifested by a profound 70-fold reduction in plasma HIV RNA levels and an almost 200-fold reduction in HIV-infected human cell numbers in mouse spleens, compared to control hu-HSC-transplanted NOD/SCID/γcnull mice inoculated with equivalent high-titer HIV-1JR-CSF. These results support the potential efficacy of this new gene therapy approach of using lentiviral vectors encoding a mixture of broadly neutralizing HIV antibodies for the treatment of HIV infection, particularly infection with multiple-drug-resistant isolates. [ABSTRACT FROM AUTHOR]

The human immunodeficiency virus type 1 (HIV-1)-specific CD8 cytotoxic T-lymphocyte (CTL) response plays a critical role in controlling HIV-1 replication. Augmenting this response should enhance control of HIV-1 replication and stabilize or improve the clinical course of the disease. Although cytomegalovirus (CMV) or Epstein-Barr virus (EBV) infection in immunocompromised patients can be treated by adoptive transfer of ex vivo-expanded CMV- or EBV-specific CTLs, adoptive transfer of ex vivo-expanded, autologous HIV-1-specific CTLs had minimal effects on HIV-1 replication, likely a consequence of the inherently compromised qualitative function of HIV-1-specific CTLs derived from HIV-1-infected individuals. We hypothesized that this limitation could be circumvented by using as an alternative source of HIV-1-specific CTLs, autologous peripheral CD8+ T lymphocytes whose antigen specificity is redirected by transduction with lentiviral vectors encoding HIV-1-specific T-cell receptor (TCR) αand ß chains, an approach used successfully in cancer therapy. To efficiently convert peripheral CD8 lymphocytes into HIV-1-specific CTLs that potently suppress in vivo HIV-1 replication, we constructed lentiviral vectors encoding the HIV-1-specific TCR αand TCR ß chains cloned from a CTL clone specific for an HIV Gag epitope, SL9, as a single transcript linked with a self-cleaving peptide. We demonstrated that transduction with this lentiviral vector efficiently converted primary human CD8 lymphocytes into HIV-1-specific CTLs with potent in vitro and in vivo HIV-1-specific activity. Using lentiviral vectors encoding an HIV-1-specific TCR to transform peripheral CD8 lymphocytes into HIV-1-specific CTLs with defined specificities represents a new immunotherapeutic approach to augment the HIV-1-specific immunity of infected patients. [ABSTRACT FROM AUTHOR]

Natural killer (NK) cells with anti-HIV-1 activity may inhibit HIV-1 replication and dissemination during acute HIV-1 infection. We hypothesized that the capacity of NK cells to suppress acute in vivo HIV-1 infection would be augmented by activating them via treatment with an interleukin-15 (IL-15) superagonist, IL-15 bound to soluble IL-15Ra, an approach that potentiates human NK cell-mediated killing of tumor cells. In vitro stimulation of human NK cells with a recombinant IL-15 superagonist significantly induced their expression of the cytotoxic effector molecules granzyme B and perforin; their degranulation upon exposure to K562 cells, as indicated by cell surface expression of CD107a; and their capacity to lyse K562 cells and HIV-1-infected T cells. The impact of IL-15 superagonist-induced activation of human NK cells on acute in vivo HIV-1 infection was investigated by using hu-spl-PBMC-NSG mice, NOD-SCID-IL2rγ-/- (NSG) mice intrasplenically injected with human peripheral blood mononuclear cells (PBMCs) which develop productive in vivo infection after intrasplenic inoculation with HIV-1. IL-15 superagonist treatment potently inhibited acute HIV-1 infection in hu-spl-PBMC-NSG mice even when delayed until 3 days after intrasplenic HIV-1 inoculation. Removal of NK cells from human PBMCs prior to intrasplenic injection into NSG mice completely abrogated IL-15 superagonist-mediated suppression of in vivo HIV-1 infection. Thus, the in vivo activation of NK cells, integral mediators of the innate immune response, by treatment with an IL-15 superagonist increases their anti-HIV activity and enables them to potently suppress acute in vivo HIV-1 infection. These results indicate that in vivo activation of NK cells may represent a new immunotherapeutic approach to suppress acute HIV-1 infection. [ABSTRACT FROM AUTHOR]

Antibodies bound to human immunodeficiency virus type 1 (HIV-1) envelope protein expressed by infected cells mobilize antibody-dependent cellular cytotoxicity (ADCC) to eliminate the HIV-1-infected cells and thereby suppress HIV-1 infection and delay disease progression. Studies treating HIV-1-infected individuals with latency reactivation agents to reduce their latent HIV-1 reservoirs indicated that their HIV-1-specific immune responses were insufficient to effectively eliminate the reactivated latent HIV-1-infected T cells. Mobilization of ADCC may facilitate elimination of reactivated latent HIV-1-infected cells to deplete the HIV-1 reservoir and contribute to a functional HIV-1 cure. The most effective antibodies for controlling and eradicating HIV-1 infection would likely have the dual capacities of potently neutralizing a broad range of HIV-1 isolates and effectively mobilizing HIV-1-specific ADCC to eliminate HIV-1-infected cells. For this purpose, we constructed LSEVh-LS-F, a broadly neutralizing, defucosylated hexavalent fusion protein specific for both the CD4 and coreceptor gp120-binding sites. LSEVh-LS-F potently inhibited in vivo HIV-1 and simian-human immunodeficiency virus (SHIV) infection in humanized mouse and macaque models, respectively, including in vivo neutralization of HIV-1 strains resistant to the broadly neutralizing antibodies VRC01 and 3BNC117. We developed a novel humanized mouse model to evaluate in vivo human NK cell-mediated elimination of HIV-1-infected cells by ADCC and utilized it to demonstrate that LSEVh-LS-F rapidly mobilized NK cells to eliminate >80% of HIV-1-infected cells in vivo 1 day after its administration. The capacity of LSEVh-LS-F to eliminate HIV-1-infected cells via ADCC combined with its broad neutralization activity supports its potential use as an immunotherapeutic agent to eliminate reactivated latent cells and deplete the HIV-1 reservoir. IMPORTANCE Mobilization of antibody-dependent cellular cytotoxicity (ADCC) to eliminate reactivated latent HIV-1-infected cells is a strategy which may contribute to depleting the HIV-1 reservoir and achieving a functional HIV-1 cure. To more effectively mobilize ADCC, we designed and constructed LSEVh-LS-F, a broadly neutralizing, defucosylated hexavalent fusion protein specific for both the CD4 and coreceptor gp120-binding sites. LSEVh-LS-F potently inhibited in vivo HIV-1 and SHIV infection in humanized mouse and macaque models, respectively, including in vivo neutralization of an HIV-1 strain resistant to the broadly neutralizing antibodies VRC01 and 3BNC117. Using a novel humanized mouse model, we demonstrated that LSEVh-LS-F rapidly mobilized NK cells to eliminate >80% of HIV-1-infected cells in vivo 1 day after its administration. The capacity of LSEVh-LS-F to eliminate HIV-1-infected cells via ADCC combined with its broad neutralization activity supports its potential use as an immunotherapeutic agent to eliminate reactivated latent cells and deplete the HIV-1 reservoir. [ABSTRACT FROM AUTHOR]

Functional analysis of T-cell responses in HIV-infected individuals has indicated that virus-specific CD8+ T cells with superior antiviral efficacy are well represented in HIV-1 controllers but are rare or absent in HIV-1 progressors. To define the role of individual T-cell receptor (TCR) clonotypes in differential antiviral CD8+ T-cell function, we performed detailed functional and mass cytometric cluster analysis of multiple CD8+ T-cell clones recognizing the identical HLA-B+2705-restricted HIV-1 epitope KK10 (KRWIILGLNK). Effective and ineffective CD8+ T-cell clones segregated based on responses to HIV-1-infected and peptide-loaded target cells. Following cognate peptide stimulation, effective HIV-specific clones displayed significantly more rapid TCR signal propagation, more efficient initial lytic granule release, and more sustained nonlytic cytokine and chemokine secretion than ineffective clones. To evaluate the TCR clonotype contribution to CD8+ T-cell function, we cloned the TCR α and β chain genes from one effective and two ineffective CD8+ T-cell clones from an elite controller into TCR-expressing lentivectors. We show that Jurkat/MA cells and primary CD8+ T cells transduced with lentivirus expressing TCR from one of the ineffective clones exhibited a level of activation by cognate peptide and inhibition of in vitro HIV-1 infection, respectively, that were comparable to those of the effective clonotype. Taken together, these data suggest that the potent antiviral capacity of some HIV-specific CD8+ T cells is a consequence of factors in addition to TCR sequence that modulate functionality and contribute to the increased antiviral capacity of HIV-specific CD8+ T cells in elite controllers to inhibit HIV infection. IMPORTANCE The greater ex vivo antiviral inhibitory activity of CD8++ T cells from elite controllers than from HIV-1 progressors supports the crucial role of effective HIV-specific CD8+ T cells in controlling HIV-1 replication. The contribution of TCR clonotype to inhibitory potency was investigated by delineating the responsiveness of effective and ineffective CD8+ T-cell clones recognizing the identical HLA-B*2705-restricted HIV-1 Gag-derived peptide, KK10 (KRWIILGLNK). KK10-stimulated "effective" CD8+ T-cell clones displayed significantly more rapid TCR signal propagation, more efficient initial lytic granule release, and more sustained cytokine and chemokine secretion than "ineffective" CD8+ T-cell clones. However, TCRs cloned from an effective and one of two ineffective clones conferred upon primary CD8+ T cells the equivalent potent capacity to inhibit HIV-1 infection. Taken together, these data suggest that other factors aside from intrinsic TCR-peptide-major histocompatibility complex (TCR-peptide-MHC) reactivity can contribute to the potent antiviral capacity of some HIV-specific CD8+ T-cell clones. [ABSTRACT FROM AUTHOR]

Human immunodeficiency virus type 1 (HIV-1)-encoded Tat provides transcriptional activation critical for efficient HIV-1 replication by interacting with cyclin T1 and recruiting P-TEFb to efficiently elongate the nascent HIV transcript. Tat-mediated transcriptional activation in mice is precluded by species-specific structural differences that prevent Tat interaction with mouse cyclin T1 and severely compromise HIV-I replication in mouse cells. We investigated whether transgenic mice expressing human cyclin T1 under the control of a murine CD4 promoter/enhancer cassette that directs gene expression to CD4+ T lymphocytes and monocytes/macrophages (hu-cycT1 mice) would display Tat responsiveness in their CD4-expressing mouse cells and selectively increase HIV-1 production in this cellular population, which is infected primarily in HIV-1-positive individuals. To this end, we crossed hu-cycT1 mice with JR-CSF transgenic mice carrying the full-length HIV-1JR-CSF provirus under the control of the endogenous HIV-1 long terminal repeat and demonstrated that human cyclin T1 expression is sufficient to support Tat-mediated transactivation in primary mouse CD4 T lymphocytes and monocytes/macrophages and increases in vitro and in vivo HIV-1 production by these stimulated cells. Increased HIV-1 production by CD4+ T lymphocytes was paralleled with their specific depletion in the peripheral blood of the JR-CSF/hu-cycT1 mice, which increased over time. In addition, increased HIV-1 transgene expression due to human cyclin T1 expression was associated with increased lipopolysaccharide-stimulated monocyte chemoattractant protein 1 production by JR-CSF mouse monocytes/ macrophages in vitro. Therefore, the JR-CSF/hu-cycT1 mice should provide an improved mouse system for investigating the pathogenesis of various aspects of HIV-1-mediated disease and the efficacies of therapeutic interventions. [ABSTRACT FROM AUTHOR]