Cell-based sialoglycan arrays for directly comparing influenza A virus receptor requirements for binding and infection.

Influenza A viruses multivalently engages sialoglycan attachment factors. Synthetic glycan arrays provide meticulous insight into primary binding specificity but do not capture dynamic post-binding virus-receptor interactions leading to cell entry. Establishing an HEK293 cell-based array of genetically dissected sialoglycan assemblies enabled screening of the complete interaction cascade from binding to infection, at physiologically relevant low virus doses.

Innate immune response after BNT162b2 COVID-19 vaccination associates with reactogenicity.

Background: The innate immune response is important for the development of the specific adaptive immunity, however it may also be associated with reactogenicity after vaccination. We explore the association between innate responsiveness, reactogenicity, and antibody response after first COVID-19 vaccination.

Methods: We included 146 healthy Dutch individuals aged 12-59 who received their first BNT162b2 (Comirnaty, Pfizer) COVID-19 vaccination.

Early immune profiling reveals distinct inflammatory responses between children and adults few days after primary SARS-CoV-2 infection.

Background: To date, it is still not clear why during the COVID-19 pandemic children generally developed no or milder symptoms compared to adults. As innate immune responses are crucial in the early defense against pathogens, we aimed at profiling these responses from both adults and children with a primary SARS-CoV-2 infection.

Methods: In the first months of the pandemic, PBMCs and serum were collected from peripheral blood of adults and children at different time points after testing SARS-CoV-2 PCR positive (PCR+).

Human Monocytes Exposed to SARS-CoV-2 Display Features of Innate Immune Memory Producing High Levels of CXCL10 upon Restimulation.

Introduction: A role for innate immune memory in protection during COVID-19 infection or vaccination has been recently reported. However, no study so far has shown whether the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can train innate immune cells. The aim of this study was to investigate whether this virus can induce trained immunity in human monocytes.

CD4 T cell-mediated recognition of a conserved cholesterol-dependent cytolysin epitope generates broad antibacterial immunity.

CD4 T cell-mediated immunity against Streptococcus pneumoniae (pneumococcus) can protect against recurrent bacterial colonization and invasive pneumococcal diseases (IPDs). Although such immune responses are common, the pertinent antigens have remained elusive. We identified an immunodominant CD4 T cell epitope derived from pneumolysin (Ply), a member of the bacterial cholesterol-dependent cytolysins (CDCs).

Diminished Pneumococcal-Specific CD4 T-Cell Response is Associated With Increased Regulatory T Cells at Older Age.

Respiratory infection caused by is a leading cause of morbidity and mortality in older adults. Acquired CD4 T cell mechanism are essential for the protection against colonization and subsequent development of infections by . In this study, we hypothesized that age-related changes within the CD4 T-cell population compromise CD4 T-cell specific responses to , thereby contributing to increased susceptibility at older age.

Sexual Dimorphism in Hepatocyte Xenograft Models.

Humanized liver mouse models are crucial tools in liver research, specifically in the fields of liver cell biology, viral hepatitis and drug metabolism. The livers of these humanized mouse models are repopulated by 3-dimensional islands of fully functional primary human hepatocytes (PHH), which are notoriously difficult to maintain in vitro. As low efficiency and high cost hamper widespread use, optimization is of great importance.

Vaccines to Protect Older Adults against Pneumococcal Disease.

Determining the optimal vaccination strategy for the protection of the elderly population against pneumococcal disease remains a challenge. Older adults are, second to young infants, most susceptible to become colonized and invaded by Streptococcus pneumoniae, causing serious disease such as bacteremic pneumonia, sepsis, and meningitis. In an era with increasing antimicrobial resistance and the growing susceptible population of aged adults, S.

Hepatitis E Virus Shows More Genomic Alterations in Cell Culture than In Vivo.

Hepatitis E Virus (HEV) mutations following ribavirin treatment have been associated with treatment non-response and viral persistence, but spontaneous occurring genomic variations have been less well characterized. We here set out to study the HEV genome composition in 2 patient sample types and 2 infection models. Near full HEV genome Sanger sequences of serum- and feces-derived HEV from two chronic HEV genotype 3 (gt3) patients were obtained.

Response kinetics reveal novel features of ageing in murine T cells.

The impact of ageing on the immune system results in defects in T cell responsiveness. The search for ageing hallmarks has been challenging due to the complex nature of immune responses in which the kinetics of T cell responsiveness have largely been neglected. We aimed to unravel hallmarks of ageing in the kinetics of the murine T cell response.

Prediction and Validation of Immunogenic Domains of Pneumococcal Proteins Recognized by Human CD4 T Cells.

CD4 T-cell mechanisms are implied in protection against pneumococcal colonization; however, their target antigens and function are not well defined. In contrast to high-throughput protein arrays for serology, basic antigen tools for CD4 T-cell studies are lacking. Here, we evaluate the potential of a bioinformatics tool for prediction of immunogenicity as a method to reveal domains of pneumococcal proteins targeted by human CD4 T cells.

Interferon-alpha treatment rapidly clears Hepatitis E virus infection in humanized mice.

Antiviral treatment options for chronic Hepatitis E Virus (HEV) infections are limited and immunological determinants of viral persistence remain largely unexplored. We studied the antiviral potency of pegylated interferon-α (pegIFNα) against HEV infections in humanized mice and modelled intrahepatic interferon stimulated gene (ISG) responses. Human gene expression levels in humanized mouse livers were analyzed by qPCR and Nanostring.

Liver Monocytes and Kupffer Cells Remain Transcriptionally Distinct during Chronic Viral Infection.

Due to the scarcity of immunocompetent animal models for chronic viral hepatitis, little is known about the role of the innate intrahepatic immune system during viral replication in the liver. These insights are however fundamental for the understanding of the inappropriate adaptive immune responses during the chronic phase of the infection. We apply the Lymphocytic Choriomenigitis Virus (LCMV) clone 13 mouse model to examine chronic virus-host interactions of Kupffer cells (KC) and infiltrating monocytes (IM) in an infected liver.

The Adhesion G Protein-Coupled Receptor GPR56/ADGRG1 Is an Inhibitory Receptor on Human NK Cells.

Natural killer (NK) cells possess potent cytotoxic mechanisms that need to be tightly controlled. Here, we explored the regulation and function of GPR56/ADGRG1, an adhesion G protein-coupled receptor implicated in developmental processes and expressed distinctively in mature NK cells. Expression of GPR56 was triggered by Hobit (a homolog of Blimp-1 in T cells) and declined upon cell activation.

Hepatitis E Virus (HEV) Genotype 3 Infection of Human Liver Chimeric Mice as a Model for Chronic HEV Infection.

Unlabelled: Genotype 3 (gt3) hepatitis E virus (HEV) infections are emerging in Western countries. Immunosuppressed patients are at risk of chronic HEV infection and progressive liver damage, but no adequate model system currently mimics this disease course. Here we explore the possibilities of in vivo HEV studies in a human liver chimeric mouse model (uPA(+/+)Nod-SCID-IL2Rγ(-/-)) next to the A549 cell culture system, using HEV RNA-positive EDTA-plasma, feces, or liver biopsy specimens from 8 immunocompromised patients with chronic gt3 HEV.

Inflammatory monocytes recruited to the liver within 24 hours after virus-induced inflammation resemble Kupffer cells but are functionally distinct.

Unlabelled: Due to a scarcity of immunocompetent animal models for viral hepatitis, little is known about the early innate immune responses in the liver. In various hepatotoxic models, both pro- and anti-inflammatory activities of recruited monocytes have been described. In this study, we compared the effect of liver inflammation induced by the Toll-like receptor 4 ligand lipopolysaccharide (LPS) with that of a persistent virus, lymphocytic choriomeningitis virus (LCMV) clone 13, on early innate intrahepatic immune responses in mice.

Chronic exposure to glucocorticoids shapes gene expression and modulates innate and adaptive activation pathways in macrophages with distinct changes in leukocyte attraction.

Glucocorticoids (GCs) have been used for more than 50 y as immunosuppressive drugs, yet their efficacy in macrophage-dominated disorders, such as chronic obstructive pulmonary disease, is debated. Little is known how long-term GC treatment affects macrophage responses in inflammatory conditions. In this study, we compared the transcriptome of human macrophages, matured in the presence or absence of fluticasone propionate (FP), and their ability to initiate or sustain classical activation, mimicked using acute LPS and chronic IFN-γ stimulation, respectively.

Microglia in normal appearing white matter of multiple sclerosis are alerted but immunosuppressed.

Little is known about the functional phenotype of microglia in normal appearing white matter (NAWM) of multiple sclerosis (MS), although it may hold valuable clues about mechanisms for lesion development. Therefore, we studied microglia from NAWM obtained post-mortem from controls (n = 25) and MS patients (n = 21) for their phenotype ex vivo and their immune responsiveness in vitro, using a microglia isolation method that omits culture and adherence. By flow cytometry, microglia in MS NAWM displayed elevated CD45 levels and increased size and granularity but were distinct from autologous choroid plexus macrophages by absent or low expression of additional markers, in particular CD206.

Phenotyping primary human microglia: tight regulation of LPS responsiveness.

Much is still unknown about mechanisms underlying the phenotypical and functional versatility of human microglia. Therefore, we developed a rapid procedure to isolate pure microglia from postmortem human brain tissue and studied their immediate ex vivo phenotype and responses to key inflammatory mediators. Microglia were isolated, along with macrophages from the choroid plexus by tissue dissociation, density gradient separation, and selection with magnetic microbeads.

Viral miRNAs exploiting the endosomal-exosomal pathway for intercellular cross-talk and immune evasion.

The class of persistent gamma-herpesviruses has developed a variety of strategies that exploit host-cell regulatory pathways to ensure a long-lasting, well-balanced infection of their host. However when these pathways are deregulated, an otherwise harmless infection can lead to disease including cancer. We recently demonstrated that the human herpes virus 4 (HHV4) also known as Epstein-Barr virus (EBV), encodes for small regulatory non-coding microRNAs (miRNAs) that can be transferred from an infected cell to uninfected neighboring cells.

Specific expression of GPR56 by human cytotoxic lymphocytes.

We here report the existence of a new cluster of adhesion-GPCRs in human immune cells. Analysis of a comprehensive immune cell transcriptome dataset indicated that expression of the closely related receptors, GPR56, GPR97, and GPR114, is associated with single lymphocyte and granulocyte subsets. Applying flow cytometric analysis with newly generated mAb, we show that expression of GPR56 is restricted to cytotoxic NK and T lymphocytes, including CD8(+), CD4(+), and γδ T cells.

A sensitive assay for virus discovery in respiratory clinical samples.

In 5-40% of respiratory infections in children, the diagnostics remain negative, suggesting that the patients might be infected with a yet unknown pathogen. Virus discovery cDNA-AFLP (VIDISCA) is a virus discovery method based on recognition of restriction enzyme cleavage sites, ligation of adaptors and subsequent amplification by PCR. However, direct discovery of unknown pathogens in nasopharyngeal swabs is difficult due to the high concentration of ribosomal RNA (rRNA) that acts as competitor.