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Summary Spontaneous control of HIV infection has been repeatedly linked to antiviral CD8+ T cells but is not always permanent. To address mechanisms of durable and aborted control of viremia, we evaluated immunologic and virologic parameters longitudinally among 34 HIV-infected subjects with differential outcomes. Despite sustained recognition of autologous virus, HIV-specific proliferative and cytolytic T cell effector functions became selectively and intrinsically impaired prior to aborted control. Longitudinal transcriptomic profiling of functionally impaired HIV-specific CD8+ T cells revealed altered expression of genes related to activation, cytokine-mediated signaling, and cell cycle regulation, including increased expression of the antiproliferative transcription factor KLF2 but not of genes associated with canonical exhaustion. Lymphoid HIV-specific CD8+ T cells also exhibited poor functionality during aborted control relative to durable control. Our results identify selective functional impairment of HIV-specific CD8+ T cells as prognostic of impending aborted HIV control, with implications for clinical monitoring and immunotherapeutic strategies.

Despite the extensive viral quasispecies that develops in an individual during the course of HIV-1 infection, transmission is typically established by a single donor viral variant. Recent studies now provide insight into the phenotypic properties influencing this selection process at transmission, including the contribution of resistance to type I interferons.

To enable the life extension of Light Water Reactors (LWRs) beyond 60 years, it is critical to gain adequate knowledge for making conclusive predictions to assure the integrity of duplex stainless steel reactor components, e.g. primary pressure boundary and reactor vessel internal. Microstructural changes in the ferrite of thermally aged, neutron irradiated only, and neutron irradiated after being thermally aged cast austenitic stainless steels (CASS) were investigated using atom probe tomography. The thermal aging was performed at 400 °C for 10,000 h and the irradiation was conducted in the Halden reactor at ~315 °C to 0.08 dpa (5.6 × 1019 n/cm2 E > 1 MeV). Low dose neutron irradiation at a dose rate of 5 × 10-9 dpa/s was found to induce spinod,al decomposition in the ferrite of as-cast microstructure, and further to enhance the spinodal decomposition in the thermally aged cast alloys. Regarding the G-phase precipitates, the neutron irradiation dramatically increases the precipitate size, and alters the composition of the precipitates with increased, Mn, Ni, Si and Mo and reduced Fe and Cr contents. Lastly, The results have shown that low dose neutron irradiation can further accelerate the degradation of ferrite in a duplex stainless steel at the LWRmore » relevant condition.« less

Humanized mice are valuable models for the research and development of vaccine strategies and therapeutic interventions to control or eradicate HIV. The BLT humanized mouse model is particularly promising because the combination of transplantation of human fetal pluripotent hematopoietic stem cells with surgical engraftment of human fetal thymic tissue results in improved T cell reconstitution, maturation, and selection. To date, the BLT humanized mouse model has been used to study many aspects of HIV infection including prevention, mucosal transmission, HIV-specific innate and adaptive immunity, viral latency, and novel antiretroviral and immune-based therapies for suppression and reservoir eradication. Here we describe recent advances and applications of the BLT humanized mouse model of HIV infection and discuss opportunities to further improve this valuable small animal model.

In support of structural material development for the fluoride-salt-cooled high-temperature reactor (FHR), corrosion tests of 316 stainless steel were performed in the potential primary coolant, molten Li2BeF4 (FLiBe) at 700 °C for an exposure duration up to 3000 h. Tests were performed in both 316 stainless steel and graphite capsules. Corrosion in both capsule materials occurred by the dissolution of chromium from the stainless steel into the salt which led to the depletion of chromium predominantly along the grain boundaries of the test samples. The samples tested in graphite capsules showed a factor of two greater depth of corrosion attack as measured in terms of chromium depletion, compared to those tested in 316 stainless steel capsules. The samples tested in graphite capsules showed the formation of Cr7C3 particulate phases throughout the depth of the corrosion layer. Samples tested in both types of capsule materials showed the formation of MoSi2 phase due to increased activity of Mo and Si as a result of Cr depletion, and furthermore corrosion promoted the formation of a α-ferrite phase in the near-surface regions of the 316 stainless steel. Based on the corrosion tests, the corrosion attack depth in FLiBe salt was predicted as 17.1 μm/year and 31.2 μm/year for 316 stainless steel tested in 316 stainless steel and in graphite capsules respectively. It is in an acceptable range compared to the Hastelloy-N corrosion in the Molten Salt Reactor Experiment (MSRE) fuel salt.

Cytotoxic T-Lymphocytes (CTLs) kill pathogen-infected or transformed cells following interaction of their T-cell receptors (TCRs) with foreign (e.g. virus-derived) peptides bound to MHC-I molecules on the target cell. TCR binding triggers CTLs to secrete perforin, which forms pores in the target cell membrane, promoting target death. Here, we show that by conjugating drug-loaded lipid nanoparticles to the surface of CTLs, their lytic machinery can be co-opted to lyse the cell-bound drug carrier, providing triggered release of drug cargo upon target cell recognition. Protein encapsulated in T-cell-bound nanoparticles was released following culture of CTLs with target cells in an antigen dose- and perforin-dependent manner and coincided with target cell lysis. Using this approach, we demonstrate the capacity of HIV-specific CTLs to deliver an immunotherapeutic agent to an anatomical site of viral replication. This strategy provides a novel means to couple drug delivery to the action of therapeutic cells in vivo., Ragon Institute of MGH, MIT and Harvard, National Institutes of Health (U.S.) (IH (AI111860)

The crystalline-to-amorphous transition in nanocrystalline silicon carbide (ncSiC) has been studied using 1.25 MeV electron irradiation. When compared to literature values for single crystal silicon carbide under electron irradiation, an increase in the dose to amorphization (DTA) was observed, indicative of an increase in radiation resistance. Factors that contribute to this improvement are grain refinement, grain texture, and a high density of stacking faults (SFs) in this sample of ncSiC. To test the effect of SFs on the DTA, density functional theory simulations were conducted. It was found that SFs reduced the energy barriers for both Si interstitial migration and the rate-limiting defect recovery reaction, which may explain the increased DTA.

In order to observe Zircaloy-4 (Zr-4) cladding oxidation within a spent fuel canister, cladding oxidized in air at 500 °C was investigated by micro-Raman spectroscopy to measure the oxide layer thickness. Systematic Raman scans were performed to study the relationship between typical Raman spectra and various oxide layer thicknesses. The thicknesses of the oxide layers developed for various exposure times were measured by cross-sectional Scanning Electron Microscopy (SEM). The results of this work reveal that each oxide layer thickness has a corresponding typical Raman spectrum. Detailed analysis suggests that the Raman scattering peaks around wave numbers of 180 cm −1 and 630 cm −1 are the best choices for accurately determining the oxide layer thickness. After Gaussian–Lorentzian deconvolution, these two peaks can be quantitatively represented by four peaks. The intensities of the deconvoluted peaks increase consistently as the oxide layer becomes thicker and sufficiently strong signals are produced, allowing one to distinguish the bare and oxidized cladding samples, as well as samples with different oxide layer thicknesses. Hence, a process that converts sample oxide layer thickness to optical signals can be achieved.

HLA-B*27 is associated with spontaneous HCV genotype 1 clearance. HLA-B*27-restricted CD8+ T cells target three NS5B epitopes. Two of these epitopes are dominantly targeted in the majority of HLA-B*27+ patients. In chronic infection, viral escape occurs consistently in these two epitopes. The third epitope (NS5B2820) was dominantly targeted in an acutely infected patient. This was in contrast, however, to the lack of recognition and viral escape in the large majority of HLA-B*27+ patients. Here, we set out to determine the host factors contributing to selective targeting of this epitope. Four-digit HLA class I typing and viral sequence analyses were performed in 78 HLA-B*27+ patients with chronic HCV genotype 1 infection. CD8+ T cell analyses were performed in a subset of patients. In addition, HLA/peptide affinity was compared for HLA-B*27:02 and 05. The NS5B2820 epitope is only restricted by the HLA-B*27 subtype HLA-B*27:02 (that is frequent in Mediterranean populations), but not by the prototype HLA-B*27 subtype B*27:05. Indeed, the epitope is very dominant in HLA-B*27:02+ patients and is associated with viral escape mutations at the anchor position for HLA-binding in 12 out of 13 HLA-B*27:02+ chronically infected patients. The NS5B2820 epitope is immunodominant in the context of HLA-B*27:02, but is not restricted by other HLA-B*27 subtypes. This finding suggests an important role of HLA subtypes in the restriction of HCV-specific CD8+ responses. With minor HLA subtypes covering up to 39% of specific populations, these findings may have important implications for the selection of epitopes for global vaccines. Financial support: CNH was supported by the Deutsche Forschungsgemeinschaft (DFG; Emmy Noether Program, NE 1567/1-1). CNH and RT were supported by the European Union (EFRE Interreg IV Oberrhein, project A30). SV was supported by the German Ministry of Education and Research (BMBF, grant no. 01 KI 1008E). DL was supported by the Ministerio de Ciencia e Innovación, Spain. This project was funded, in part, by Federal funds from the National Institute of Allergy and Infectious Diseases (NIAID), grants R01-AI067926 (TMA) and U19 AI082630 (TMA and GML), and the Swiss HIV Cohort Study, supported by the Swiss National Science Foundation (grant #33CS30_134277). Sí

Summary HIV-1 primarily infects T lymphocytes and uses these motile cells as migratory vehicles for effective dissemination in the host. Paradoxically, the virus at the same time disrupts multiple cellular processes underlying lymphocyte motility, seemingly counterproductive to rapid systemic infection. Here we show by intravital microscopy in humanized mice that perturbation of the actin cytoskeleton via the lentiviral protein Nef, and not changes to chemokine receptor expression or function, is the dominant cause of dysregulated infected T cell motility in lymphoid tissue by preventing stable cellular polarization required for fast migration. Accordingly, disrupting the Nef hydrophobic patch that facilitates actin cytoskeletal perturbation initially accelerates systemic viral dissemination after female genital transmission. However, the same feature of Nef was subsequently critical for viral persistence in immune-competent hosts. Therefore, a highly conserved activity of lentiviral Nef proteins has dual effects and imposes both fitness costs and benefits on the virus at different stages of infection.

A defect disorder model has been developed to determine equilibrium off-stoichiometry and its spatial variations in UO2 crystals. The model gives the concentrations of atomic defects and electronic carriers as functions of oxygen partial pressure and temperature in the bulk and near crystal surfaces subject to an oxygen environment. Energetic parameters from published density functional theory calculations have been integrated into the defect disorder model for an accurate determination of the defect density and off-stoichiometry. The ionosorption theory has been used to couple the oxygen environment with the defect state in the crystal as we solved for the defect disorder near crystal surfaces. Contrary to the common belief that hyper-stoichiometry of UO2 is dominated by oxygen interstitials, the current model predicts that this regime is rather dominated by uranium vacancies. The model predictions also show that, in the presence of surfaces, the point defect concentrations vary by orders of magnitude in the subsurface region relative to the bulk region.

For a more effective examination of microstructure in Al–Mg alloys, a new etching solution has been developed; dissolved ammonium persulfate in water. It is demonstrated how β phase (Al3Mg2) in Al–Mg alloys respond to this solution using samples of a binary Al–Mg alloy and a commercial 5083 aluminum alloy. Nanometer sized β phase is clearly visualized for the first time using scanning electron microscopy (SEM) instead of transmission electron microscopy (TEM). It is anticipated that direct and unambiguous visualization of β phase will greatly augment intergranular corrosion research in 5xxx series aluminum alloys.

CeO 2-x films were deposited by sputtering a metal Ce target in a gas mixture of high purity Ar and O 2 using a pulsed unbalanced magnetron sputtering system. In this work, cerium oxide thin films were grown onto silicon substrates under different O 2 flow rates, which were varied from 20 to 80% of the total flow rate with simultaneous changes in the Ar flow rate. In addition, different growth conditions and the influence of post-deposition rapid thermal annealing (RTA) were performed to tailor the stoichiometry of the cerium oxide films. The microstructure and mechanical properties of the films were characterized using electron probe microanalysis (EPMA), X-ray diffraction, field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, and nano-indentation. EPMA results revealed that all as-deposited CeO 2-x films have an O/Ce ratio about 1.75. When the post-annealing temperature ( T PA ) for the films was increased from 800 to 1100 °C, a reduction of oxygen in the film was observed, which led to a phase transition from cubic CeO 2-x (111) to hexagonal Ce 2 O 3 (002). This phase transition is related to Ce 4 + to Ce 3 + cation transformation due to the formation of oxygen vacancies. The hardness and elastic modulus of the as-deposited CeO 2-x films were 11.7 GPa and 241 GPa, respectively, which were reduced to about 7.5 GPa and 150 GPa, respectively, after annealing at 1100 °C.

Ni electroplating of Incoloy-800H was investigated with the goal of mitigating Cr dissolution from this alloy into molten 46.5%LiF–11.5%NaF–42%KF eutectic salt, commonly referred to as FLiNaK. Tests were conducted in graphite crucibles at a molten salt temperature of 850 °C. The crucible material graphite accelerates the corrosion process due to the large activity difference between the graphite and the alloy. For the purposes of providing a baseline for this study, un-plated Incoloy-800H and a nearly pure Ni-alloy, Ni-201 were also tested. Results indicate that Ni-plating has the potential to significantly improve the corrosion resistance of Incoloy-800H in molten fluoride salts. Diffusion of Cr from the alloy through the Ni-plating does occur and if the Ni-plating is thin enough this Cr eventually dissolves into the molten salt. The post-corrosion test microstructure of the Ni-plating, particularly void formation was also observed to depend on the plating thickness. Diffusion anneals in a helium environment of Ni-plated Incoloy-800H and an Fe–Ni–Cr model alloy were also investigated to understand Cr diffusion through the Ni-plating. Further enhancements in the efficacy of the Ni-plating as a protective barrier against Cr dissolution from the alloy into molten fluoride salts can be achieved by thermally forming a Cr 2 O 3 barrier film on the surface of the alloy prior to Ni electroplating.

DNA immunization in conjunction with antiretroviral therapy was evaluated in SIV-infected rhesus macaques treated with [R]-9-[2-phosphonylmethoxypropyl]adenine (PMPA). Macaques were immunized monthly with DNA vaccines expressing either SIV gag/tat or SIV gag/tat and 19 CD8+ T cell epitopes during 7 months of therapy. Half the animals from each group were additionally immunized before infection. Only 60% of the animals (4 controls, 20 vaccinated) responded to PMPA (ART responders). All 4 ART responder controls demonstrated viral rebound or CD4 decline after PMPA was withdrawn. In contrast, 17 of 20 vaccinated ART responders contained viral rebound for over 7 months after PMPA was withdrawn. Viral control correlated with stable CD4 counts, higher lymphoproliferation and an increase in the magnitude and breadth of the CD8+ T cell response. Immunizing before infection or with multi-epitopes enhanced these effects. These results demonstrate that DNA immunization during antiretroviral therapy may be an effective strategy to treat HIV infection.

BACKGROUND and AIMS: Cellular immune responses are thought to play a key role in the resolution of primary HCV infection. Although it has been consistently shown that CD4+ T-cell responses are maintained in those with spontaneous resolution but lost in those with persistent infection, the role of CD8+ T-cell responses remains controversial. Previous studies have largely focused on limited HLA alleles and predefined CD8+ T-cell epitopes, and, thus, comprehensive studies remain to be performed. METHODS: To understand the composition of the immune response associated with spontaneous resolution, we comprehensively mapped CD8+ T-cell responses in 20 HLA-diverse persons with resolved HCV infection, using HCV peptides spanning the entire genome. We analyzed the magnitude, breadth, function, and phenotype using ELISpot, class-I tetramers, intracellular cytokine staining, and cytolytic assays. We studied in parallel HCV-specific responses and viral sequence variation in persistent infection. RESULTS: Responses in individuals with resolved infection were strong and broad with robust proliferation in response to antigen. Responses in those persistently infected were rarely detected ex vivo and, when present, were narrowly directed and weak. However, they also proliferated in vitro. Dominant target epitopes differed among individuals in both cohorts, despite frequently shared HLA-alleles. CONCLUSIONS: These data indicate that persisting, strong CD8+ T-cell responses are observed in the majority of persons with resolved HCV infection and provide support for strategies to boost CD8+ T-cell responses for the prevention or treatment of HCV infection but also highlight the diversity of responses that may need to be elicited to provide protection.

During the past year, a number of reports have described HIV-1 superinfection in human subjects, defined as the reinfection of an individual with a second heterologous strain of HIV-1. These reports have challenged the assumption that HIV-1-specific immune responses generated during primary infection are protective against subsequent infection and have raised concern, not only with respect to HIV-1-positive individuals engaging in unsafe sex but also from the standpoint of developing effective vaccines. Herein we review the published reports of HIV-1 superinfection and highlight studies providing additional insight into the potential for HIV-1 superinfections to affect the global epidemic.

Twenty years into the HIV epidemic, highly active antiretroviral therapy (HAART) represents the only effective intervention to control HIV-1 disease progression. However, the prospect of life-long treatment with HAART is challenging given cumulative drug toxicities, difficulties with adherence to complicated regimens and the looming emergence of drug-resistant viruses. The challenges are even greater in resource-poor settings where costs and logistical problems with delivery represent formidable obstacles. Alternative approaches to long-term control of viral replication and disease progression are clearly needed.

Rhesus macaques were immunized with a replication-deficient vaccinia virus (MVA) expressing human immunodeficiency virus type 1 89.6 envelope (env) and SIV gagpol (MVA/SHIV89.6) with or without a protein boost consisting of soluble 89.6 env (gp140). Immunization with MVA/SHIV89.6 alone elicited binding antibodies in all animals and neutralizing antibodies in 5 of 15 animals. Both types of antibodies were enhanced by protein boosting. In addition, CD8 cells exhibiting CM9 tetramer binding were detected in the subset of animals that were Mamu-A*01 positive. Animals were challenged intravenously with either SHIV-89.6 (Study 1) or the more pathogenic derivative SHIV-89.6P (Study 2). In Study 1, all control and vaccinated animals except one became infected. However, the levels of viremia were as follows: controls > rMVA alone > rMVA + protein. The differences were statistically significant between immunized and control groups but not between the two immunized groups. In Study 2, all animals became infected; however, the vaccinated group exhibited a 5-fold reduction in peak viremia and a 10-fold reduction in the postacute phase viremia in comparison to the controls. All of the controls required euthanasia by 10 months after challenge. A relationship between vaccine-induced antibody titers and reduction in virus burden was observed in both studies. Thus, immunization with MVA/SHIV89.6 alone or with a protein boost stimulated both arms of the immune system and resulted in significant control of viremia and delayed progression to disease after challenge with SHIV-89.6P.

This article describes a novel approach to HIV vaccine design that is, as yet, unproven and still in preliminary development. In rhesus macaques infected with simian immunodeficiency virus (SIV), we have identified particular cellular immune responses that select for viral variants during primary infection. We speculate that the detection of viral variants with altered amino acids in CTL epitopes implies the successful clearance of cells harboring wild-type virus. Here, we present our rationale suggesting why such potent early CTL responses that exert an antiviral effect may be particularly attractive targets for induction by candidate vaccines. Conventional wisdom suggests that regions of the virus that are structurally and functionally important will generally be well-conserved both among clades and within an infected host. Amino acid replacements within these well-conserved regions should be difficult for the virus to accommodate. Therefore, these regions are traditionally considered ideal targets for vaccine induced immune responses because they are refractory to CTL escape mutations. Many examples of these regions have been identified in both HIV-1 and SIV(mac) (J. Immunol. 162 (1999) 3727; J. Virol. 67 (1993) 438) and have been included in candidate vaccine formulations. Human clinical trials testing these vaccines are currently underway. Our proposed method of vaccination with CTL epitopes that escape explores an alternative hypothesis. Rather than engendering responses to regions of the virus that do not escape, we reason that vaccination needs to accelerate the development of the initial immune responses that effectively select for amino acid variants during acute infection. By examining CTL escape during the acute phase, we will identify CTL responses that the virus cannot tolerate and incorporate these responses into vaccines.

We present results for the simultaneous detection of volatile organic compounds, semivolatile organic compounds, and organometallic compounds in air and water by using membrane introduction ion trap mass spectrometry. In these experiments, a membrane composed of a microporous polypropylene hollow support fiber coated with an ultrathin (∼0.5 μm) polydimethylsiloxane layer serves as the interface between the sample and the vacuum of the mass spectrometer. Simultaneous detection of benzene, naphthalene, and ferrocene in aqueous solution is achieved by proton transfer chemical ionization using H3O+ from membrane-diffused water. With the same membrane, we also demonstrate the simultaneous detection of methyl ethyl ketone, toluene, 1-methylnaphthalene, and ferrocene in air with chemical ionization employing membrane-diffused oxygen from air as the reagent gas.