Tetramer enrichment reveals the presence of phenotypically diverse hepatitis C virus-specific CD8+T cells in chronic infection

Virus-specific CD8+ T cells are rarely detectable ex vivo by conventional methods during chronic hepatitis C virus (HCV) infection. In this study, however, we were able to detect and characterize HCV-specific CD8+ T cells in all chronically HCV genotype 1a-infected, HLA-A*02:01-positive patients analyzed by performing major histocompatibility complex (MHC) class I tetramer enrichment. Two-thirds of these enriched HCV-specific CD8+ T-cell populations displayed an effector memory phenotype, whereas, surprisingly, one-third displayed a naive-like phenotype despite ongoing viral replication. CD8+ T cells with an effector memory phenotype could not expand in vitro, suggesting exhaustion of these cells. Interestingly, some of the naive-like CD8+ T cells proliferated vigorously upon in vitro priming, whereas others did not. These differences were linked to the corresponding viral sequences in the respective patients. Indeed, naive-like CD8+ T cells from patients with the consensus sequence in the corresponding T-cell epitope did not expand in vitro. In contrast, in patients displaying sequence variations, we were able to induce HCV-specific CD8+ T-cell proliferation, which may indicate infection with a variant virus. Collectively, these data reveal the presence of phenotypically and functionally diverse HCV-specific CD8+ T cells at very low frequencies that are detectable in all chronically infected patients despite viral persistence. IMPORTANCE In this study, we analyzed CD8+ T-cell responses specific for HLA-A*02:01-restricted epitopes in chronically HCV-infected patients, using MHC class I tetramer enrichment. Importantly, we could detect HCV-specific CD8+ T-cell populations in all patients. To further characterize these HCV-specific CD8+ T-cell populations that are not detectable using conventional techniques, we performed phenotypic, functional, and viral sequence analyses. These data revealed different mechanisms for CD8+ T-cell failure in HCV infection, including T-cell exhaustion, viral escape, and functional impairment of naive-like HCV-specific CD8+ T cells

Quantitative Comparison of Different Approaches for Reconstructing the Carbon-Binder Domain from Tomographic Image Data of Cathodes in Lithium-Ion Batteries and Its Influence on Electrochemical Properties

It is well known that the spatial distribution of the carbon binder domain CBD offers a large potential to further optimize lithium ion batteries. However, it is challenging to reconstruct the CBD from tomographic image data obtained by synchrotron tomography. Herein, several approaches are considered to segment 3D image data of two different cathodes into three phases, namely, active material, CBD, and pores. More precisely, it is focused on global thresholding, a local closing approach based on energy dispersive X ray spectroscopy data, a k means clustering method, and a procedure based on a neural network that has been trained by correlative microscopy, i.e., based on data gained by synchrotron tomography and focused ion beam scanning electron microscopy data representing the same electrode. The impact of the considered segmentation approaches on morphological characteristics as well as on the resulting performance by spatially resolved transport simulations is quantified. Furthermore, experimentally determined electrochemical properties are used to identify an appropriate range for the effective transport parameter of the CBD. The developed methodology is applied to two differently manufactured cathodes, namely, an ultrathick unstructured cathode and a two layer cathode with varying CBD content in both layers. This comparison elucidates the impact of a specific structuring concept on the 3D microstructure of cathode

Incomplete tumour control following DNA vaccination against rat gliomas expressing a model antigen

Background Vaccination against tumour-associated antigens is one approach to elicit anti-tumour responses. We investigated the effect of polynucleotide (DNA) vaccination using a model antigen (E. coli lacZ) in a syngeneic gliosarcoma model (9L). Methods Fisher 344 rats were vaccinated thrice by intramuscular injection of a lacZ-encoding or a control plasmid in weekly intervals. One week after the last vaccination, lacZ-expressing 9L cells were implanted into the striatum. Results After 3 weeks, in lacZ-vaccinated animals the tumours were significantly smaller than in control-vaccinated animals. In cytotoxic T cell assays lysis rates of >50 % could only be observed in a few of the lacZ-vaccinated animals. This response was directed against lacZ-expressing and parental 9L cells but not against syngeneic MADB 106 adenocarcinoma cells. In Elispot assays interferon-γ production was observed upon stimulation with 9LlacZ and 9L wild-type but not MADB 106 cells. This response was higher for lacZ-immunized animals. All animals revealed dense infiltrates with CD8+ lymphocytes and, to a lesser extent, with NK cells. CD25-staining indicated cells possibly associated with the maintenance of peripheral tolerance to self-antigens. All tumours were densely infiltrated by microglia consisting mostly of ramified cells. Only focal accumulation of macrophage-like cells expressing ED1, a marker for phagocytic activity, was observed. Conclusion Prophylactic DNA vaccination resulted in effective but incomplete suppression of brain tumour formation. Mechanisms other than cytotoxic T cell responses as measured in the generally used in vitro assays appear to play a role in tumour suppression

Influence of conductive additive and binder domain distribution and its structural properties on macroscopic impedances

The conductive additive and binder domain (CBD) is an essential component of Lithium-ion battery electrodes. It enhances the electrical connectivity and mechanical stability within an electrode matrix. Migration of the binder during electrode drying leads to an inhomogeneous distribution of the CBD, impeding transport of lithium ions in the electrolyte, and diminishing the electronic pathways between solid particles[1]. The effect of this migration on the electrochemical performance of NMC622 electrodes is quantitatively investigated via microstructure-resolved 3D simulations and compared with experimental results. The virtual electrode microstructures are based on tomographic data. The valuable information derived from combining microstructure-resolved models[2] with electrochemical impedance spectroscopy (EIS) simulations on symmetric cells is used to characterize the lithium ion transport in the electrode pore space, including the contributions of the CBD. Additionally, half-cell discharge simulations are conducted to quantify the effect on performance. In the above simulations, the CBD is treated as a homogenized phase with effective transport parameters, not resolving its internal nano-structure. A key aspect for predictively determining the physical and chemical processes occurring are the intrinsic properties of the CBD. To develop a more predictive model, we need to characterize and understand the properties of the CBD on the nano-scale. In the present contribution, high-resolution 3D FIB-SEM data is used to obtain further geometric information on the porous networks within the CBD, shedding light on its effective ionic conductivity. This information is then fed back to the model, allowing us to account for the tortuosity on the nano-scale in the CBD domain

Effect of a Heterogeneous Distribution of the Conductive Additives and Binder Domain on the Impedances of Lithium-Ion Battery Electrodes

The conductive additive and binder domain (CBD) is an essential component of Lithium-ion battery electrodes. It enhances the electrical connectivity and mechanical stability within an electrode matrix. Migration of the binder during electrode drying leads to an inhomogeneous distribution of the CBD, impeding transport of Lithium ions into the electrodes, and diminishing the electronic pathways between solid particles. Therefore, we investigate the effect of binder migration on the electrochemical performance of NMC622 electrodes via microstructure-resolved 3D simulations, and compare them with experimental results. The virtual electrode microstructures are based on tomographic data. The valuable information derived from combining microstructure-resolved models with electrochemical impedance spectroscopy (EIS) simulations on symmetric cells is used to characterize the Lithium-ion transport in the electrode pore space, including the contributions of the CBD. Additionally, half-cell discharge simulations are also conducted. Through our work, we demonstrate the significance of the CBD distribution and enable predictive simulations for future battery design