Influenza Virus-specific CD8+ T Cells

Influenza viruses are among the leading causes of acute respiratory tract infections worldwide. Natural influenza virus infections elicit both humoral and cellular immune responses. Although, neutralizing antibodies directed to the hemagglutinin (HA) globular head domain prevent reinfection with the same influenza virus they exert limited/no cross-reactivity with antigenically drifted variants or influenza viruses of different strains, it is therefore of interest to identify other correlates of protection. Cellular immunity, especially influenza virus-specific CD8+ cytotoxic T lymphocytes (CTLs), contribute to rapid clearance of influenza virus infections and thereby reduce viral shedding. Influenza virus-specific CTLs, elicited after seasonal influenza virus infections, are mainly directed to conserved internal proteins. In this dissertation we were able to demonstrate the cross-reactivity of seasonal influenza virus-specific CTLs with the novel and potentially pandemic A/H7N9 virus and between different lineages of influenza B viruses. Furthermore, using an unique PBMC donor cohort we were able to assess the longevity of these cells in healthy individuals. In addition, we were able to demonstrate that human influenza A viruses can impair the recognition of the HLA-A*0201 restricted and highly conserved M158-66 epitope by specific CTLs by variations in the extra-epitopic amino acids. This CTL evasion strategy may have implications for the viral replication kinetics in HLA-A*0201 individuals and thus the spread of influenza A viruses in the human population. Finally, we describe a novel adjuvant, G3/DT, that improves the immunogenicity of a standard inactivated seasonal influenza vaccine in terms of enhancing the antibody response and inducing a protective CTL response

A compensatory mutagenesis study of a conserved hairpin in the M gene segment of influenza A virus shows its role in virus replication

RNA structures are increasingly recognized to be of importance during influenza A virus replication. Here, we investigated a predicted conserved hairpin in the M gene segment (nt 967-994) within the region of the vRNA 5′ packaging signal. The existence of this RNA structure and its possible role in virus replication was investigated using a compensatory mutagenesis approach. Mutations were introduced in the hairpin stem, based on natural variation. Virus replication properties were studied for the mutant viruses with disrupted and restored RNA structures. Viruses with structure-disrupting mutations had lower virus titers and a significantly reduced median plaque size when compared with the wild-type (WT) virus, while viruses with structure restoring-mutations replicated comparable to WT. Moreover, virus replication was also reduced when mutations were introduced in the hairpin loop, suggesting its involvement in RNA interactions. Northern blot and FACS experiments were performed to study differences in RNA levels as well as production of M1 and M2 proteins, expressed via alternative splicing. Stem-disruptive mutants caused lower vRNA and M2 mRNA levels and reduced M2 protein production at early time-points. When the RNA structure was restored, vRNA, M2 mRNA and M2 protein levels were increased, demonstrating a compensatory effect. Thus, this study provides evidence for functional importance of the predicted M RNA structure and suggests its role in splicing regulation

Monday Musing, February 8, 2016, Vol 3, no.6

It is a compilation of information, practical advice, training announcements, and/or success stories. Monday Musings is intended to disseminate information to Early Childhood Iowa Stakeholders in a timely fashion

Modified Vaccinia Virus Ankara Preferentially Targets Antigen Presenting Cells in Vitro, Ex Vivo and in Vivo

Modified Vaccinia virus Ankara (MVA) is a promising vaccine vector with an excellent safety profile. However, despite extensive pre-clinical and clinical testing, surprisingly little is known about the cellular tropism of MVA, especially in relevant animal species. Here, we performed in vitro, ex vivo and in vivo experiments with recombinant MVA expressing green fluorescent protein (rMVA-GFP). In both human peripheral blood mononuclear cells and mouse lung explants, rMVA-GFP predominantly infected antigen presenting cells. Subsequent in vivo experiments performed in mice, ferrets and non-human primates indicated that preferential targeting of dendritic cells and alveolar macrophages was observed after respiratory administration, although subtle differences were observed between the respective animal species. Following intramuscular injection, rMVA-GFP was detected in interdigitating cells between myocytes, but also in myocytes themselves. These data are important in advancing our understanding of the basis for the immunogenicity of MVA-based vaccines and aid rational vaccine design and delivery strategies

Immune dynamics in SARS-CoV-2 experienced immunosuppressed rheumatoid arthritis or multiple sclerosis patients vaccinated with mRNA-1273

BACKGROUND: Patients affected by different types of autoimmune diseases, including common conditions such as multiple sclerosis (MS) and rheumatoid arthritis (RA), are often treated with immunosuppressants to suppress disease activity. It is not fully understood how the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific humoral and cellular immunity induced by infection and/or upon vaccination is affected by immunosuppressants. METHODS: The dynamics of cellular immune reactivation upon vaccination of SARS-CoV-2 experienced MS patients treated with the humanized anti-CD20 monoclonal antibody ocrelizumab (OCR) and RA patients treated with methotrexate (MTX) monotherapy were analyzed at great depth via high-dimensional flow cytometry of whole blood samples upon vaccination with the SARS-CoV-2 mRNA-1273 (Moderna) vaccine. Longitudinal B and T cell immune responses were compared to SARS-CoV-2 experienced healthy controls (HCs) before and 7 days after the first and second vaccination. RESULTS: OCR-treated MS patients exhibit a preserved recall response of CD8(+) T central memory cells following first vaccination compared to HCs and a similar CD4(+) circulating T follicular helper 1 and T helper 1 dynamics, whereas humoral and B cell responses were strongly impaired resulting in absence of SARS-CoV-2-specific humoral immunity. MTX treatment significantly delayed antibody levels and B reactivation following the first vaccination, including sustained inhibition of overall reactivation marker dynamics of the responding CD4(+) and CD8(+) T cells. CONCLUSIONS: Together, these findings indicate that SARS-CoV-2 experienced MS-OCR patients may still benefit from vaccination by inducing a broad CD8(+) T cell response which has been associated with milder disease outcome. The delayed vaccine-induced IgG kinetics in RA-MTX patients indicate an increased risk after the first vaccination, which might require additional shielding or alternative strategies such as treatment interruptions in vulnerable patients. FUNDING: This research project was supported by ZonMw (The Netherlands Organization for Health Research and Development, #10430072010007), the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement (#792532 and #860003), the European Commission (SUPPORT-E, #101015756) and by PPOC (#20_21 L2506), the NHMRC Leadership Investigator Grant (#1173871)

Human influenza a virus-specific CD8⁺ T-cell response is long-lived

Animal and human studies have demonstrated the importance of influenza A virus (IAV)-specific CD8+ cytotoxic T lymphocytes (CTLs) in heterosubtypic cross-protective immunity. Using peripheral blood mononuclear cells obtained intermittently from healthy HLA-typed blood donors between 1999 and 2012, we were able to demonstrate that IAV-specific CTLs are long-lived. Intercurrent IAV infections transiently increase the frequency of functionally distinct subsets of IAV-specific CTLs, in particular effector and effector memory T cells

ASURE Clinical Trial Protocol:A Randomized, Placebo-Controlled, Proof-of-Concept Study Aiming to Evaluate Safety and Target Engagement following Administration of TW001 in Early Alzheimer’s Disease Patients

Background: Alzheimer’s disease (AD) is a neurodegenerative disease with complex disease etiology and pathological processes. These include formation of plaques and tangles, aberrant lipid processing, neuroinflammation, cerebrovascular dysregulation, ion channel and mitochondrial dysfunction, and oxidative stress. Disease-modifying therapies focusing on all these different facets are needed. TW001 is an oral formulation with the radical scavenger edaravone as its active ingredient, targeting oxidative stress. Objectives: This manuscript describes the trial design for Phase IIA Alzheimer Study Using oRal Edaravone (ASURE). Methods: ASURE is a randomized, placebo-controlled, proof-of-concept study aiming to evaluate safety and target engagement following administration of TW001 in early AD patients. Patients should have a biomarker confirmed diagnosis to be included in the trial and will be treated for 90 days. The primary endpoints include safety and effect of TW001 on oxidative stress biomarkers. Exploratory endpoints focus on a panel of AD(-related) fluid-based biomarkers and EEG. In addition, a recently developed cognitive functional composite (CFC) score will measure early signs of cognitive and functional effects of TW001. Results: This article outlines the design of the clinical study, no results are included. Conclusions: The ASURE trial design is discussed, with a particular focus on fluid biomarkers, EEG, and CFC as endpoints. By testing multiple measures related to pathology, pharmacodynamics, EEG as proxy for cognition, and cognitive functional scores, it is expected that small changes will be detectable in trials of shorter duration. Moreover, the wide range of endpoints allows to make well-informed decisions for designing pivotal studies later

Human CD8(+) T Cells Damage Noninfected Epithelial Cells during Influenza Virus Infection In Vitro

Microscopic imaging and technolog