Biology subjects

Schwemmle, M.

Publications and source records attributed to Schwemmle, M..

3 recordsLinked to original sources

bioRxiv2021

Genome-Wide CRISPR Screening Identifies BRD9 as a Druggable Component of Interferon-Stimulated Gene Expression and Antiviral Activity

Transient interferon (IFN) induction of IFN-stimulated genes (ISGs) creates a formidable protective antiviral state. However, loss of appropriate control mechanisms can result in constitutive pathogenic ISG upregulation. Here, we used genome-wide loss-of-function screening to establish genes critical for IFN signaling, identifying all expected members of the JAK-STAT pathway and the previously unappreciated bromodomain-containing protein 9 (BRD9), a defining subunit of non-canonical BAF (ncBAF) chromatin remodeling complexes. Genetic knock-out or small-molecule mediated degradation of BRD9 limited IFN-induced expression of a subset of ISGs in multiple cell-types, and prevented IFN from exerting full antiviral activity against several RNA and DNA viruses. Mechanistically, BRD9 acts at the level of ISG transcription, exhibits a proximal association with STAT2 following IFN stimulation, and relies on its intact acetyl-binding bromodomain and unique ncBAF scaffolding function for activity. Given its druggability, BRD9 may be an attractive target for dampening constitutive ISG expression under certain pathogenic autoinflammatory conditions.

immunology↗

bioRxiv2020

Ex vivo detection of SARS-CoV-2-specific CD8+ T cells: rapid induction, prolonged contraction, and formation of functional memory

CD8+ T cells are critical for the elimination and long-lasting protection of many viral infections, but their role in the current SARS-CoV-2 pandemic is unclear. Emerging data indicates that SARS-CoV-2-specific CD8+ T cells are detectable in the majority of individuals recovering from SARS-CoV-2 infection. However, optimal virus-specific epitopes, the role of pre-existing heterologous immunity as well as their kinetics and differentiation program during disease control have not been defined in detail. Here, we show that both pre-existing and newly induced SARS-CoV-2-specific CD8+ T-cell responses are potentially important determinants of immune protection in mild SARS-CoV-2 infection. In particular, our results can be summarized as follows: First, immunodominant SARS-CoV-2-specific CD8+ T-cell epitopes are targeted in the majority of individuals with convalescent SARS-CoV-2 infection. Second, MHC class I tetramer analyses revealed the emergence of phenotypically diverse and functionally competent pre-existing and newly induced SARS-CoV-2-specific memory CD8+ T cells that showed similar characteristics compared to influenza-specific CD8+ T cells. Third, SARS-CoV-2-specific CD8+ T-cell responses are more robustly detectable than antibodies against the SARS-CoV-2-spike protein. This was confirmed in a longitudinal analysis of acute-resolving infection that demonstrated rapid induction of the SARS-CoV-2-specific CD8+ T cells within a week followed by a prolonged contraction phase that outlasted the waning humoral immune response indicating that CD8+ T-cell responses might serve as a more precise correlate of antiviral immunity than antibody measurements after convalescence. Collectively, these data provide new insights into the fine specificity, heterogeneity, and dynamics of SARS-CoV-2-specific memory CD8+ T cells, potentially informing the rational development of a protective vaccine against SARS-CoV-2.

immunology↗

bioRxiv2018

The bat influenza H17N10 can be neutralized by broadly-neutralizing monoclonal antibodies and its neuraminidase can facilitate viral egress.

The diversity of subtypes within the Influenza A virus genus has recently expanded with the identification of H17N10 and H18N11 from bats. In order to further study the tropism and zoonotic potential of these viruses, we have successfully produced lentiviral pseudotypes bearing both haemagglutinin H17 and neuraminidase N10. These pseudotypes were shown to be efficiently neutralized by the broadly-neutralizing monoclonal antibodies CR9114 and FI6. Our studies also confirm previous reports that H17 does not use sialic acid as its cellular receptor, as pseudotypes bearing the H17 envelope glycoprotein are released into the cell supernatant in the absence of NA. However, we demonstrate that N10 facilitates heterosubtypic (H5 and H7) influenza HA-bearing pseudotype release in the absence of another source of NA, significantly increasing luciferase pseudotype production titres. Despite this, N10 shows no activity in the enzyme-linked lectin assay used for traditional sialidases. These findings suggest that this protein plays an important role in viral egress, but is perhaps involved in further accessory roles in the bat influenza lifecycle that are yet to be discovered. Thus we show the lentiviral pseudotype system is a useful research tool, and amenable for investigation of bat influenza tropism, restriction and sero-epidemiology, without the constraints or safety issues with producing a replication-competent virus, to which the human population is naive.\n\nSignificance statementInfluenza virus is responsible for mortality and morbidity across the globe; human populations are constantly at risk of newly emerging strains from the aquatic bird reservoir which harbors most of the subtypes of influenza A (H1-H16). Recently identified subtypes (H17N10, H18N11) from bats have broadened the reservoir from which potential pandemic strains of influenza can emerge. To evaluate the potential for these novel subtypes to cross over into human populations, their ability to establish an infection, in addition to the extent of cross-reactive immunity established by human seasonal strains needs to be investigated. This study highlights a novel platform for the study of the bat H17 and N10 envelope glycoproteins, using a lentiviral pseudotype system. Following the generation of this pseudotype it was employed in cell entry and microneutralization assays. These showed that two well-characterised monoclonal antibodies (mAb) which target avian and human influenza subtypes will also neutralize H17. Furthermore the data presented in this study show a novel aspect of the N10 glycoprotein in its ability to facilitate the budding of pseudotypes bearing different influenza HAs.

microbiology↗