Biology subjects

Waldran, M. J.

Publications and source records attributed to Waldran, M. J..

4 recordsLinked to original sources

bioRxiv2024

Dengue virus structural proteins are expressed on the surface of DENV-infected cells and are a target for antibody-dependent cellular phagocytosis

Dengue virus (DENV) is an arboviral pathogen found in over 100 countries and a source of significant morbidity and mortality. While the mechanisms underpinning the pathophysiology of severe dengue are incompletely understood, it has been previously suggested that antibodies directed against the DENV envelope (E) protein can facilitate antibody dependent enhancement (ADE) of the infection, increasing the number of infected cells and the severity of infection in an exposed individual. Accordingly, there is interest in defining mechanisms for directly targeting DENV-infected cells for immunologic clearance, an approach that bypasses the risk of ADE. We have previously demonstrated that antibodies specific for DENV non-structural protein 1 (NS1) can opsonize and facilitate the phagocytic clearance of DENV infected cells. However, it is currently unclear if other DENV antigens are expressed on the surface of infected cells, and if these antigens can be targeted by antibody-dependent clearance mechanisms. In this study, we demonstrate that DENV structural proteins are expressed on the surface of DENV-infected cells, and that these antigens can be opsonized by both DENV-immune sera and monoclonal antibodies. In addition, DENV E-specific antibodies can facilitate phagocytic uptake of DENV-infected cells, resulting in the target-cell membrane localizing to endosomes of the engulfing phagocyte. Notably, no DENV genetic material was observed localizing to the engulfing phagocyte, suggesting that horizontal transfer of DENV from the infecting cell is an unlikely occurrence. In their totality, these data reinforce the concept that DENV E-reactive antibodies have a multifaceted role in DENV immunity and pathogenesis beyond neutralization and/or infection-enhancement.

immunology↗

bioRxiv2024

Antibody-dependent DENV infection induces distinct transcriptomic responses in infected and bystander human macrophages

Dengue virus (DENV) is a mosquito-borne flavivirus which coexists as four genetically and immunologically distinct serotypes (DENV1-4). In secondary heterologous DENV infection, pre-existing immunity is believed to contribute to severe disease through antibody dependent enhancement (ADE). Although the elevated pathology observed in ADE conditions has been described, the cell intrinsic mechanisms governing this process remain unclear. Using scRNAseq, we investigated the transcriptomic profiles of human monocyte-derived macrophages infected by DENV via ADE compared to conventional infection conditions. Unsupervised analysis of scRNAseq data enabled the identification and differentiation of infected and bystander/uninfected cells in a heterogeneous cell culture. Differential gene expression and Ingenuity Pathway analyses revealed a number of significantly up- and down-regulated genes and gene networks between cells infected by ADE compared to conventional infection. Specifically, these pathways indicated mechanisms such as suppressed interferon signaling and inflammatory chemokine transcription in cells infected via ADE. Further analysis revealed that transcriptomic changes were independent of viral RNA within infected cells, suggesting that the observed changes are reflective of cell-intrinsic responses and not simply a function of per-cell viral burden. Bystander cells in ADE conditions also demonstrated distinct profiles, indicating an immunologically activated phenotype enriched for the expression of gene networks involved with protein translation, cytokine production, and antigen presentation. Together, these findings support the concept that DENV infection via ADE induces a qualitatively different transcriptomic response in infected and bystander cells, contributing to our understanding of ADE as a mechanistic driver of disease and pathogenesis. IMPORTANCEDengue virus (DENV) is a mosquito-borne human pathogen with a significant and growing global health burden. Although correlates of severe dengue disease are poorly understood, pre-existing immunity to DENV has been associated with severe disease risk and known to contribute to an alternative route of viral entry termed antibody-dependent enhancement (ADE). Using single cell RNA sequencing, we identified distinct transcriptomic processes involved in antibody-mediated DENV entry compared to conventional receptor mediated entry. These data provide meaningful insight into the discrete processes contributing to DENV pathogenesis in ADE conditions.

immunology↗

bioRxiv2022

Soluble NS1 antagonizes IgG- and IgA-mediated monocytic phagocytosis of DENV infected cells

Dengue virus (DENV) is endemic in over 100 countries, infecting an estimated 400 million individuals every year. Infection with DENV raises a significant antibody response, primarily consisting of antibodies targeting viral (structural) proteins. However, not all DENV antigens are part of the virion itself, as the DENV genome encodes several non-structural (NS) proteins. One of these, NS1, has been shown to be antigenic and is expressed on the membrane of DENV-infected cells. IgG and IgA isotype antibodies that bind NS1 are detectable in serum following DENV infection and are also capable of interacting with Fc receptors expressed on professional phagocytes. Our study aims to determine if NS1-binding IgG and IgA isotype antibodies contribute to the clearance of DENV-infected cells by professional phagocytes through antibody mediated phagocytosis/trogocytosis. Using an in vitro model of trogocytosis we observed that both IgG and IgA isotype antibodies can facilitate facilitating monocytic uptake of DENV NS1 expressing plasma membrane in an additive fashion. This process was dependent on the expression of Fc{gamma}RI (CD64) and FcR (CD89) for IgG and IgA mediated membrane uptake, respectively. Furthermore, this process was antagonized by the presence of soluble NS1, suggesting that the production of soluble NS1 by infected cells may serve as an immunological chaff, thereby antagonizing opsonization and clearance of infected cells by NS1-specific IgG and IgA isotype antibodies.

immunology↗

bioRxiv2021

Simultaneous analysis of antigen-specific B and T cells after SARS-CoV-2 infection and vaccination

Conventional methods for quantifying and phenotyping antigen-specific lymphocytes can rapidly deplete irreplaceable specimens. This is due to the fact that antigen-specific T and B cells have historically been analyzed in independent assays each requiring millions of cells. A technique that facilitates the simultaneous detection of antigen-specific T and B cells would allow for more thorough immune profiling with significantly reduced sample requirements. To this end, we developed the B And T cell Tandem Lymphocyte Evaluation (BATTLE) assay, which allows for the simultaneous identification of SARS-CoV-2 Spike reactive T and B cells using an optimized Activation Induced Marker (AIM) T cell assay and dual-color B cell antigen probes. Using this assay, we demonstrate that antigen-specific B and T cell subsets can be identified simultaneously using conventional flow cytometry platforms and provide insight into the differential effects of mRNA vaccination on B and T cell populations following natural SARS-CoV-2 infection.

immunology↗