Lindholmwren2605

Antibody-dependent enhancement (ADE) of infection is an alternative mechanism of infection for viruses to infect immune cells that is mediated by antibodies and IgG receptors (FcγRs). Because ADE of infection contributes to the pathogenesis of some viruses, such as dengue virus and feline coronavirus, it is important to evaluate the precise mechanism of ADE and its contribution to the pathogenesis of SARS-CoV-2. Here, using convalescent-phase plasma from COVID-19 patients, we found that two types of FcγRs, FcγRIIA and FcγRIIIA, mediate ADE of SARS-CoV-2 infection. Although ADE of infection was observed for SARS-CoV-2 and its recent variants, proinflammatory cytokine production in monocyte-derived macrophages was not upregulated. These observations suggest that SARS-CoV-2 infection produces antibodies that elicit ADE of infection, but these antibodies may not be involved in aberrant cytokine release by macrophages during SARS-CoV-2 infection.Phenotypic heterogeneity among single cells in a genetically identical population leads to diverse environmental adaptation. The human and animal pathogen Salmonella enterica serovar Typhimurium exhibits heterogeneous expression of virulence genes, including flagellar and Salmonella pathogenicity island (SPI) genes. Little is known about how the differential expression of flagellar genes among single cells affects bacterial adaptation to stresses. Here, we have developed a triple-fluorescence reporter to simultaneously monitor the expression of flagellar and SPI-1 pathways. We show that the two pathways cross talk at the single-cell level. Intriguingly, cells expressing flagella (fliC-ON) exhibit decreased tolerance to antibiotics compared to fliC-OFF cells. Such variation depends on TolC-dependent efflux pumps. We further show that fliC-ON cells contain higher intracellular proton concentrations. This suggests that the assembly and rotation of flagella consume the proton motive force and decrease the efflux refore gains benefits from such diversity to quickly adapt to different environmental conditions.In 2019, a new pandemic virus belonging to the betacoronavirus family emerged, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This new coronavirus appeared in Wuhan, China, and is responsible for severe respiratory pneumonia in humans, namely, coronavirus disease 2019 (COVID-19). Having infected almost 200 million people worldwide and caused more than 4.1 million deaths as of today, this new disease has raised a significant number of questions about its molecular mechanism of replication and, in particular, how infectious viral particles are produced. Although viral entry is well characterized, the full assembly steps of SARS-CoV-2 have still not been fully described. Coronaviruses, including SARS-CoV-2, have four main structural proteins, namely, the spike glycoprotein (S), the membrane glycoprotein (M), the envelope protein (E), and the nucleocapsid protein (N). All these proteins have key roles in the process of coronavirus assembly and budding. In this review, we gathered the current knowledge about betacoronavirus structural proteins involved in viral particle assembly, membrane curvature and scission, and then egress in order to suggest and question a coherent model for SARS-CoV-2 particle production and release.Burkholderia cenocepacia is a member of the Burkholderia cepacia complex (Bcc), a group of bacteria with members responsible for causing lung infections in cystic fibrosis (CF) patients. The most severe outcome of Bcc infection in CF patients is cepacia syndrome, a disease characterized by necrotizing pneumonia with bacteremia and sepsis. B. cenocepacia is strongly associated with cepacia syndrome, making it one of the most virulent members of the Bcc. Mechanisms underlying the pathogenesis of B. cenocepacia in lung infections and cepacia syndrome remain to be uncovered. B. cenocepacia is primarily an intracellular pathogen and encodes the type VI secretion system (T6SS) effector TecA, which is translocated into host phagocytes. TecA is a deamidase that inactivates multiple Rho GTPases, including RhoA. Inactivation of RhoA by TecA triggers assembly of the pyrin inflammasome, leading to secretion of proinflammatory cytokines, such as interleukin-1β, from macrophages. Previous work with the B. cenocepacia clini not been identified in a CF animal model of lung infection. Results of this study describe a CF mouse model and its use in demonstrating that the T6SS effector TecA of B. cenocepacia exacerbates inflammatory cell recruitment and weight loss and is required for lethality and, thus, acts as a key virulence factor during lung infection. This model will be important in further studies to better understand TecA's role as a virulence factor and in investigating ways to prevent or treat B. cenocepacia infections in CF patients. Additionally, TecA may be the founding member of a family of virulence factors in opportunistic pathogens.In HIV-1 infection, many antibodies (Abs) are elicited to Envelope (Env) epitopes that are conformationally masked in the native trimer and are only available for antibody recognition after the trimer binds host cell CD4. Among these are epitopes within the Co-Receptor Binding Site (CoRBS) and the constant region 1 and 2 (C1-C2 or cluster A region). In particular, C1-C2 epitopes map to the gp120 face interacting with gp41 in the native, "closed" Env trimer present on HIV-1 virions or expressed on HIV-1-infected cells. Antibodies targeting this region are therefore nonneutralizing and their potential as mediators of antibody-dependent cellular cytotoxicity (ADCC) of HIV-1-infected cells diminished by a lack of available binding targets. Here, we present the design of Ab-CD4 chimeric proteins that consist of the Ab-IgG1 of a CoRBS or cluster A specificity to the extracellular domains 1 and 2 of human CD4. Our Ab-CD4 hybrids induce potent ADCC against infected primary CD4+ T cells and neutralize tier 1 and 2 HIVy fusion molecules in which domains 1 and 2 of soluble human CD4 are linked with monoclonal antibodies of either the CoRBS or cluster A specificity. We optimized the conjugation sites and linker lengths to allow each of these novel bispecific fusion molecules to recognize native "closed" Env trimers and induce the structural rearrangements required for exposure of the epitopes for antibody binding. Our in vitro functional testing shows that our Ab-CD4 molecules can efficiently target and eliminate HIV-1-infected cells through antibody-dependent cellular cytotoxicity and inactivate HIV-1 virus through neutralization.The emergence and worldwide dissemination of carbapenemase-producing Gram-negative bacteria are a major public health threat. Metallo-β-lactamases (MBLs) represent the largest family of carbapenemases. Regrettably, these resistance determinants are spreading worldwide. Among them, the New Delhi metallo-β-lactamase (NDM-1) is experiencing the fastest and largest geographical spread. NDM-1 β-lactamase is anchored to the bacterial outer membrane, while most MBLs are soluble, periplasmic enzymes. This unique cellular localization favors the selective secretion of active NDM-1 into outer membrane vesicles (OMVs). Here, we advance the idea that NDM-containing vesicles serve as vehicles for the local dissemination of NDM-1. We show that OMVs with NDM-1 can protect a carbapenem-susceptible strain of Escherichia coli upon treatment with meropenem in a Galleria mellonella infection model. Survival curves of G. mellonella revealed that vesicle encapsulation enhances the action of NDM-1, prolonging and favoring bacterialrotect carbapenem-susceptible strains of E. coli and P. aeruginosa upon treatment with meropenem in a live infection model. selleck screening library These vesicles act as nanoparticles that encapsulate and transport NDM-1, prolonging and favoring its action against meropenem inside a living organism. Secretion of NDM-1 into vesicles contributes to the survival of otherwise susceptible nearby bacteria at infection sites. We propose that vesicles play a role in the establishment of bacterial communities and the dissemination of antibiotic resistance, in addition to traditional horizontal gene transfer mechanisms.The FliE component of the bacterial flagellum is the first protein secreted through the flagellar type III secretion system (fT3SS) that is capable of self-assembly into the growing bacterial organelle. The FliE protein plays dual roles in the assembly of the Salmonella flagellum as the final component of the flagellar type III secretion system (fT3SS) and as an adaptor protein that anchors the rod (drive shaft) of the flagellar motor to the membrane-imbedded MS-ring structure. This work has identified the interactions between FliE and other proteins at the inner membrane base of the flagellar machine. The fliE sequence coding for the 104-amino-acid protein was subject to saturating mutagenesis. Single-amino-acid substitutions were generated in fliE, resulting in motility phenotypes. From these mutants, intergenic suppressor mutations were generated, isolated, and characterized. Single-amino-acid mutations defective in FliE function were localized to the N- and C-terminal helices of the protein. Motile suppre, axial structure that spans the periplasmic space, penetrates the outer membrane, and extends 10 to 20 microns from the cell surface. This work combines genetic mutant suppressor analysis with the structural data for the core T3S system, the MS-ring, and the axial drive shaft (rod) that transverses the periplasm to provide insight into the essential adaptor role of FliE in flagellum assembly and function.Microbes colonize the apical surfaces of polarized epithelia in nearly all animal taxa. In one example, the luminous bacterium Vibrio fischeri enters, grows to a dense population within, and persists for months inside, the light-emitting organ of the squid Euprymna scolopes. Crucial to the symbiont's success after entry is the ability to trigger the constriction of a host tissue region (the "bottleneck") at the entrance to the colonization site. Bottleneck constriction begins at about the same time as bioluminescence, which is induced in V. fischeri through an autoinduction process called quorum sensing. Here, we asked the following questions (i) Are the quorum signals that induce symbiont bioluminescence also involved in triggering the constriction? (ii) Does improper signaling of constriction affect the normal maintenance of the symbiont population? We manipulated the presence of three factors, the two V. fischeri quorum signal synthases, AinS and LuxI, the transcriptional regulator LuxR, and light emission. Using the monospecific squid-vibrio model of symbiosis, we examined how quorum-sensing regulation by the Vibrio fischeri population induces a biogeographic tissue phenotype that promotes the retention of this extracellular symbiont within the light organ of its host, Euprymna scolopes. Understanding the influence of bacterial symbionts on key sites of tissue architecture has implications for all horizontally transmitted symbioses, especially those that colonize an epithelial surface within the host.

To investigate the time sequence of brain magnetic resonance imaging findings of spontaneous intracranial hypotension.

We retrospectively reviewed the medical records and brain magnetic resonance imaging findings of consecutive patients with spontaneous intracranial hypotension hospitalized between January 2007 and December 2017. Patients were divided into quartiles based on intervals between initial spontaneous intracranial hypotension symptom onset and brain magnetic resonance imaging scan. Six categorical and five continuous brain magnetic resonance imaging findings were assessed, including venous distension sign, enlarged pituitary gland, diffuse pachymeningeal enhancement, mid-brain pons deformity, subdural fluid collection, flattening of pons, midbrain-pons angle, descent of cerebral aqueduct, mamillopontine distance, distance of suprasellar cistern, and distance of prepontine cistern. In addition, we also calculated the neuroimaging scores with a score ≥5 classified as 'high probability of spontaneous intracranial hypotension' and a score ≥3 as 'intermediate-to-high probability.