Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infection are global health problems affecting 600 million people worldwide. Indeed, HBV and HCV are hepatotropic viruses that can cause acute and chronic liver disease progressing to liver cirrhosis and even hepatocellular carcinoma. Furthermore, co-infections of HBV and HCV with HIV are emerging worldwide. These co-infections are even more likely to develop persistent infection and are difficult to treat. There is growing evidence that virus-specific CD4+ and CD8+ T-cell responses play a central role in the outcome and pathogenesis of HBV and HCV infection. While virus-specific T-cell responses are able to successfully clear the virus in a subpopulation of patients, failure of these T-cell responses is associated with the development of viral persistence. In this review article, we will discuss similarities and differences in HBV- and HCV-specific T-cell responses that are central in determining viral clearance, persistence and liver disease.

Background: Cardiac surgery often represents the only treatment option in patients with infective endocarditis (IE). However, IE surgery may lead to a sudden release of inflammatory mediators, which is associated with the severity of postoperative organ dysfunction. We investigated the impact of hemoadsorption during IE surgery on postoperative organ dysfunction. Methods: This multi-center, randomized, non-blinded, controlled trial assigned patients undergoing cardiac surgery for IE to hemoadsorption [integration of CytoSorb® to cardiopulmonary bypass (CPB)] or control. The Primary outcome (ΔSOFA) was defined as the difference between the mean total postoperative sequential organ failure assessment score (SOFA), calculated maximally to the 9th postoperative day, and the basal SOFA score. The analysis was by modified intention-to-treat. A predefined inter-group comparison was done using a linear mixed model for ΔSOFA including surgeon and baseline SOFA as fixed effect covariates and with the surgical center as random effect. The SOFA score assesses dysfunction in six organ systems, each scored from zero to four. Higher scores indicate worsening dysfunction. Secondary outcomes were 30-day mortality, durations of mechanical ventilation, vasopressor and renal replacement therapy. Cytokines were measured in the first 50 patients. Results: Between January 17, 2018 and January 31, 2020, A total of 288 patients were randomly assigned to hemoadsorption (n=142) or control (n=146). Four patients in the hemoadsorption and two in the control group were excluded as they did not undergo surgery. The primary outcome ΔSOFA did not differ between the hemoadsorption and the control group (1.79 ± 3.75 and 1.93 ± 3.53, respectively, 95% CI: −1.30 to 0.83, p=0.6766). Mortality at 30 days (21% hemoadsorption vs 22% control, p=0.782), the durations of mechanical ventilation, vasopressor and renal replacement therapy did not differ between groups. Levels of IL-1β and IL-18 at the end of CPB were significantly lower in the hemoadsorption than in the control group. Conclusions: This randomized trial failed to demonstrate a reduction in postoperative organ dysfunction through intraoperative hemoadsorption in patients undergoing cardiac surgery for IE. Although hemoadsorption reduced plasma cytokines at the end of CPB, there was no difference in any of the clinically relevant outcome points.

The impact of naïve-precursor frequency on human virus-specific CD8؉ T cell immunodominance is not well understood. Using a recently developed major histocompatibility complex (MHC) class I tetramer enrichment protocol, we found a conserved hierarchy and a >10-fold difference in naïve-precursor frequencies across three HLA-A2-restricted hepatitis C virus (HCV)-specific epitopes. Importantly, the NS3 1406 epitope with the highest naïve-precursor frequency in healthy donors was also the most frequently targeted epitope in a large cohort of chronically HCV-infected patients, both ex vivo and after in vitro stimulation. These results indicate for the first time that immunodominance in a human viral infection is linked to naïve-precursor frequency.

We report on a new camera that is based on a pnCCD sensor for applications in scanning transmission electron microscopy. Emerging new microscopy techniques demand improved detectors with regards to readout rate, sensitivity and radiation hardness, especially in scanning mode. The pnCCD is a 2D imaging sensor that meets these requirements. Its intrinsic radiation hardness permits direct detection of electrons. The pnCCD is read out at a rate of 1,150 frames per second with an image area of 264 × 264 pixel. In binning or windowing modes, the readout rate is increased almost linearly, for example to 4,000 frames per second at 4× binning (264 × 66 pixel). Single electrons with energies from 300 keV down to 5 keV can be distinguished due to the high sensitivity of the detector. Three applications in scanning transmission electron microscopy are highlighted to demonstrate that the pnCCD satisfies experimental requirements, especially fast recording of 2D images. In the first application, 65,536 2D diffraction patterns were recorded in 70 s. STEM images corresponding to intensities of various diffraction peaks were reconstructed. For the second application, the microscope was operated in a Lorentz-like mode. Magnetic domains were imaged in an area of 256 × 256 sample points in less than 37 seconds for a total of 65,536 images each with 264 × 132 pixels. Due to information provided by the two-dimensional images, not only the amplitude but also the direction of the magnetic field could be determined. In the third application, millisecond images of a semiconductor nanostructure were recorded to determine the lattice strain in the sample. A speed-up in measurement time by a factor of 200 could be achieved compared to a previously used camera system.

Human leukocyte antigen B27 (HLA-B27) is associated with protection in human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infection. This protective role is linked to single immunodominant HLA-B27-restricted CD8+ T-cell epitopes in both infections. In order to define the relative contribution of a specific HLA-B27-restricted epitope to the natural course of HCV infection, we compared the biological impact of the highly conserved HCV genotype 1 epitope, for which the protective role has been described, with the corresponding region in genotype 3 that differs in its sequence by three amino acid residues. The genotype 3a peptide was not recognized by CD8+ T cells specific for the genotype 1 peptide. Furthermore, patients with acute or chronic infection with HCV genotype 3a did not mount T-cell responses to this epitope region, and their autologous viral sequences showed no evidence of T-cell pressure. Finally, we found a significantly higher frequency of HLA-B27 positivity in patients with chronic HCV genotype 3a infection compared to genotype 1 infection, indicating that there is no protection by HLA-B27 in HCV genotype 3 infection. Conclusion Our data indicate that the protective effect of HLA-B27 is limited to HCV genotype 1 infection and does not expand to other genotypes such as genotype 3a. This can most likely be explained by intergenotype sequence diversity leading to the loss of the immunodominant HLA-B27 epitope in viral strains other than genotype 1. Our results underline the central role of a single HLA-B27-restricted epitope-specific CD8+ T-cell response in mediating protection in HCV genotype 1 infection.

HLA-B27 is associated with spontaneous viral clearance in hepatitis C virus (HCV) infection. Viral escape within the immunodominant HLA-B27 restricted HCV-specific CD8+ T cell epitope NS5B2841-2849 (ARMILMTHF) has been shown to be limited by viral fitness costs as well as broad T cell cross-recognition, suggesting a potential mechanism of protection by HLA-B27. Here, we studied the subdominant HLA-B27 restricted epitope NS5B2936-2944 (GRAAICGKY) in order to further define the mechanisms of protection by HLA-B27. We identified a unique pattern of escape mutations within this epitope in a large cohort of HCV genotype 1a infected patients. The predominant escape mutations represented conservative substitutions at the main HLA-B27 anchor residue or a T cell receptor contact site, neither of which impaired viral replication capacity as assessed in a subgenomic HCV replicon system. In contrast, however, in a subset of HLA-B27+ subjects rare escape mutations arose at the HLA-B27 anchor residue R2937, which nearly abolished viral replication. Notably, these rare mutations only occurred in conjunction with the selection of two equally rare, and structurally proximal, upstream mutations. Co-expression of these upstream mutations with the rare escape mutations dramatically restored viral replication capacity from <5% to ≥70% of wild-type levels. Conclusion The selection of rare CTL escape mutations in this HLA-B27 restricted epitope dramatically impairs viral replicative fitness unless properly compensated. These data support a role for the targeting of highly-constrained regions by HLA-B27 in its ability to assert immune control of HCV and other highly variable pathogens.

The transition of adolescents with chronic conditions is a challenging task. This study aimed to explore the experiences and needs of adolescents with chronic conditions in the transition period and to apply these findings to the design of a generic patient education programme. Data were collected from a sample of 29 adolescents with chronic conditions from Northern Germany and Switzerland including a broad range of views due to variation in disease management and organisation of care both in paediatric and adult populations. Participants were interviewed in group (n = 18) or individual (n = 11) interviews between September 2011 and February 2012, and the data were analysed using qualitative content analysis. The findings revealed that the interviewees expressed high levels of competency in the management of their chronic conditions but identified gaps in healthcare and unmet needs during transition. In particular, they believed that they would benefit from opportunities to exchange ideas and more specific information with peers about vocational and medical issues concerning adolescent health. Identified themes reflecting adolescent needs were used to develop the transition workshop including modules regarding the following: transfer to adult medicine, their new role as a patient, orientation within the healthcare system, vocational issues, detachment from parents, social support, contraception, substance abuse, family planning, stress-management, activation of resources and developing personal goals. The workshop's content was largely generic and included some condition-specific components. The workshop was designed as a compact 2-day patient education programme in a group setting for adolescents prior to their transfer to adult care. The guiding principle was the idea of empowerment by supporting the adolescents through various interactive methods to develop adequate knowledge, skills, understanding and motivation regarding their chronic conditions. We conclude that patient education programmes promoting adolescent self-management and empowerment increase the preparedness for transition.

Growth dynamics of Pseudomonas aeruginosa, Burkholderia cepacia, and Staphylococcus aureus in a batch and chemostat, were investigated as a laboratory model system for persistent infections in cystic fibrosis. Most species-specific enumeration methods for mixed cultures are laborious or only qualitative, and therefore impede generation of quantitative data required for validation of mathematical models. Here, a quantitative T-RFLP method was evaluated and applied for specific and absolute cell number enumerations. The method was tested to be unbiased by quantitative sample composition and allowed reproducible enumerations of mixed cultures. For assay validation, samples of defined concentration containing one, two or three species were quantified. Logarithmically transformed absolute cell numbers of single-species dilutions were linear within a lower working range of 10(4)-10(6) cfu/mL (species-dependent) and an upper working range of 10(10) cfu/mL. Quantifications of single species (10(6)-10(10) cfu/mL) spiked with one or two other species agreed well with single species controls. Differences between slopes of first order linear regression of spiked and pure dilution series were insignificant. Coefficient of variation of defined mixed replicates was maximum 4.39%, of a three-species chemostat it was maximum 1.76%. T-RFLP monitoring of pure cultures in parallel shake flasks and of a three-species mixed chemostat gave very consistent results. Coexistence of at least two species after a time period equivalent to more than 33 volume exchanges was found. This result was not predicted from pure cultures clearly indicating the need for quantitative mixed culture experiments to better understand microbial growth dynamics and for mathematical model validation.