Biology subjects

Brandi, J.

Publications and source records attributed to Brandi, J..

3 recordsLinked to original sources

bioRxiv2026

CD81 is an Ebola virus inhibiting factor that is antagonized by GP and VP40

Viruses manipulate the host cell membrane of infected cells for evasion of antiviral immunity, prevention of superinfection and optimization of viral replication and spread. The Ebola virus glycoprotein (EBOV GP) mediates virus entry, but is also known as important factor for subversion of the hosts antiviral immune response. We characterized the dysregulation of cell surface-residing proteins by EBOV GP and found that among several membrane proteins GP interferes with the tetraspanins CD81, CD63 and CD9. This was a conserved function of several filoviral GPs and not observable for viral glycoproteins of other virus families. While CD63 and CD9 were largely dispensable for EBOV replication, CD81 suppressed virus-like particle entry and replication at multiple steps. This phenotype might be explainable by sustained suppression of NF{kappa}B by CD81, that is otherwise activated by VP40 and EBOV trVLP replication. We further demonstrate that not only GP but also VP40 interferes with CD81 functionality and that antibody-mediated clustering of CD81 suppresses EBOV infection. Altogether, the tetraspanin CD81 emerges as druggable NF{kappa}B and EBOV-inhibiting factor, supporting an important role of NF{kappa}B in EBOV replication and potentially virus-induced immunopathogenesis. HighlightsO_LIEBOV GP and VP40 interfere with CD81 cell surface expression C_LIO_LICD81 suppresses NF{kappa}B signaling which is activated by VP40 C_LIO_LICD81 restricts EBOV VLP uptake and replication C_LIO_LITargeting CD81 by a crosslinking antibody inhibits EBOV infection C_LI

microbiology↗

bioRxiv2022

Plant signals anticipate the induction of the type III secretion system in Pseudomonas syringae pv. actinidiae facilitating efficient temperature-dependent effector translocation

Disease resistance in plants depends on a molecular dialogue with microbes that involves many known chemical effectors, but the time course of the interaction and the influence of the environment are largely unknown. The outcome of host-pathogen interactions is thought to reflect the offensive and defensive capabilities of both players. When plants interact with Pseudomonas syringae, several well-characterized virulence factors contribute to early bacterial pathogenicity, including the type III secretion system (T3SS), which must be activated by signals from the plant and environment to allow the secretion of virulence effectors. The manner in which these signals regulate T3SS activity is still unclear. Here, we strengthen the paradigm of the plant-pathogen molecular dialogue by addressing overlooked details concerning the timing of interactions, specifically the role of plant signals and temperature on the regulation of bacterial virulence during the first few hours of the interaction. Whole-genome expression profiling after 1 h revealed that the perception of plant signals from kiwifruit or tomato extracts anticipates T3SS expression in P. syringae pv. actinidiae compared to apoplast-like conditions, facilitating more efficient effector transport in planta, as revealed by the induction of a temperature-dependent hypersensitive response in the non-host plant Arabidopsis thaliana Col-0. Our results show that, in the arms race between plants and bacteria, the temperature-dependent timing of bacterial virulence versus the induction of plant defenses is probably one of the fundamental parameters governing the outcome of the interaction. Abstract importancePlant diseases- their occurrence and severity- result from the impact of three factors: the host, the pathogen, and the environmental conditions, interconnected in the disease triangle. Time was further included as a fourth factor accounting for plant disease, leading to a more realistic three-dimensional disease pyramid to represent the evolution of disease over time. However, this representation still considers time only as a parameter determining when and to which extent a disease will occur, at a scale from days to months. Here, we show that time is a factor regulating the arms race between plants and pathogens, at a scale from minutes to hours, and strictly depends on environmental factors. Thus, besides the arms possessed by pathogens and plants per se, the opportunity and the timing of arms mobilization should make the difference to determine the outcome of an interaction and thus the occurrence of plant disease.

microbiology↗

bioRxiv2021

T cells expressing multiple co-inhibitory molecules in acute malaria are not exhausted but exert a suppressive function

Overwhelming activation of T cells in acute malaria is associated with severe outcomes. Thus, counter-regulation by anti-inflammatory mechanisms is indispensable for an optimal resolution of disease. Using Plasmodium berghei ANKA (PbA) infection of C57BL/6 mice, we performed a comprehensive analysis of co-inhibitory molecules expressed on CD4+ and CD8+ T cells using an unbiased cluster analysis approach. We identified similar T cell clusters co-expressing several co-inhibitory molecules like programmed cell death protein 1 (PD-1) and lymphocyte activation gene 3 (LAG-3) in the CD4+ and the CD8+ T cell compartment. Interestingly, despite expressing co-inhibitory molecules, which are associated with T cell exhaustion in chronic settings, these T cells were more functional compared to activated T cells that were negative for co-inhibitory molecules. However, T cells expressing high levels of PD-1 and LAG-3 also conferred suppressive capacity and thus resembled type I regulatory T cells. To our knowledge, this is the first description of malaria-induced CD8+ T cells with suppressive capacity. Importantly, we found an induction of T cells with a similar co-inhibitory rich phenotype in Plasmodium falciparum infected patients. In conclusion, we demonstrate that malaria-induced T cells expressing co-inhibitory molecules are not exhausted, but acquire additional suppressive capacity, which might represent an immune regulatory pathway to prevent further activation of T cells during acute malaria.

immunology↗