At-home sampling to meet geographical challenges for serological assessment of SARS-CoV-2 exposure in a rural region of northern Sweden, March to May 2021: a retrospective cohort study.

BackgroundThe current SARS-CoV-2 pandemic has highlighted a need for easy and safe blood sampling in combination with accurate serological methodology. Venipuncture for testing is usually performed by trained staff at healthcare centres. Long travel distances to healthcare centres in rural regions may introduce a bias of testing towards relatively large communities with closer access.

CRISPR-Cas-Guided Mutagenesis of Chromosome and Virulence Plasmid in Shigella flexneri by Cytosine Base Editing.

Shigella is a Gram-negative bacterium that invades the human gut epithelium. The resulting infection, shigellosis, is the deadliest bacterial diarrheal disease. Much of the information about the genes dictating the pathophysiology of Shigella, both on the chromosome and the virulence plasmid, was obtained by classical reverse genetics.

Infection-induced membrane ruffling initiates danger and immune signaling via the mechanosensor PIEZO1.

Microorganisms are generally sensed by receptors recognizing microbial molecules, which evoke changes in cellular activities and gene expression. Bacterial pathogens induce secretion of the danger signal ATP as an early alert response of intestinal epithelial cells, initiating overt inflammation. However, what triggers ATP secretion during infection is unclear.

Generation of plasma cells and CD27IgD B cells during hantavirus infection is associated with distinct pathological findings.

Objective: Human hantavirus infections can cause haemorrhagic fever with renal syndrome (HFRS). The pathogenic mechanisms are not fully understood, nor if they affect the humoral immune system. The objective of this study was to investigate humoral immune responses to hantavirus infection and to correlate them to the typical features of HFRS: thrombocytopenia and transient kidney dysfunction.

Whole-genome Identification of Transcriptional Start Sites by Differential RNA-seq in Bacteria.

Gene transcription in bacteria often starts some nucleotides upstream of the start codon. Identifying the specific Transcriptional Start Site (TSS) is essential for genetic manipulation, as in many cases upstream of the start codon there are sequence elements that are involved in gene expression regulation. Taken into account the classical gene structure, we are able to identify two kinds of transcriptional start site: primary and secondary.

cytotoxin MakA induces noncanonical autophagy resulting in the spatial inhibition of canonical autophagy.

Autophagy plays an essential role in the defense against many microbial pathogens as a regulator of both innate and adaptive immunity. Some pathogens have evolved sophisticated mechanisms that promote their ability to evade or subvert host autophagy. Here, we describe a novel mechanism of autophagy modulation mediated by the recently discovered cytotoxin, motility-associated killing factor A (MakA).

Serological assessment of SARS-CoV-2 exposure in northern Sweden by the use of at-home sampling to meet geographical challenges in rural regions.

The current SARS-CoV-2 pandemic has highlighted a need for easy and safe blood sampling in combination with accurate serological methodology. Venipuncture is usually performed by trained staff at health care centers. Long travel distances may introduce a bias of testing towards relatively large communities with close access to health care centers.

Complete genome sequence and annotation of the laboratory reference strain Shigella flexneri serotype 5a M90T and genome-wide transcriptional start site determination.

Background: Shigella is a Gram-negative facultative intracellular bacterium that causes bacillary dysentery in humans. Shigella invades cells of the colonic mucosa owing to its virulence plasmid-encoded Type 3 Secretion System (T3SS), and multiplies in the target cell cytosol. Although the laboratory reference strain S.

Plaque Assay to Determine Invasion and Intercellular Dissemination of in TC7 Human Intestinal Epithelial Cells.

invades the epithelial cells lining the gut lumen and replicates intracellularly. The specialized Type III Secretion System (T3SS) and its effector proteins, encoded on a large virulence plasmid, assist the bacterium to gain access to the cytosol. Thereafter disseminates to neighboring cells in an epithelial layer without further extracellular steps.

Gentamicin Protection Assay to Determine the Number of Intracellular Bacteria during Infection of Human TC7 Intestinal Epithelial Cells by .

is an intracellular bacterial pathogen that gains access to the gut epithelium using a specialized Type III Secretion System (T3SS). Various determinants mediating this invasive infection have been experimentally verified using the classical gentamicin protection assay presented here. In this assay epithelial cell lines are infected by bacteria and the extracellular bacteria are killed by gentamicin.

PI5P Triggers ICAM-1 Degradation in Shigella Infected Cells, Thus Dampening Immune Cell Recruitment.

Shigella flexneri, the pathogen responsible for bacillary dysentery, has evolved multiple strategies to control the inflammatory response. Here, we show that Shigella subverts the subcellular trafficking of the intercellular adhesion molecule-1 (ICAM-1), a key molecule in immune cell recruitment, in a mechanism dependent on the injected bacterial enzyme IpgD and its product, the lipid mediator PI5P. Overexpression of IpgD, but not a phosphatase dead mutant, induced the internalization and the degradation of ICAM-1 in intestinal epithelial cells.

Distinct mutations led to inactivation of type 1 fimbriae expression in Shigella spp.

Shigella spp. are responsible for bacillary dysentery in humans. The acquisition or the modification of the virulence plasmid encoding factors promoting entry of bacteria into and dissemination within epithelial cells was a critical step in the evolution of these bacteria from their Escherichia coli ancestor(s).

Type III secretion system.

The type III secretion system (T3SS) is a membrane-embedded nanomachine found in several Gram-negative bacteria. Upon contact between bacteria and host cells, the syringe-like T3SS (Figure 1) transfers proteins termed effectors from the bacterial cytosol to the cytoplasm or the plasma membrane of a single target cell. This is a major difference from secretion systems that merely release molecules into the extracellular milieu, where they act on potentially distant target cells expressing the relevant surface receptors.

A Shigella effector dampens inflammation by regulating epithelial release of danger signal ATP through production of the lipid mediator PtdIns5P.

Upon infection with Shigella flexneri, epithelial cells release ATP through connexin hemichannels. However, the pathophysiological consequence and the regulation of this process are unclear. Here we showed that in intestinal epithelial cell ATP release was an early alert response to infection with enteric pathogens that eventually promoted inflammation of the gut.

Preventing acute gut wall damage in infectious diarrhoeas with glycosylated dendrimers.

Intestinal pathogens use the host's excessive inflammatory cytokine response, designed to eliminate dangerous bacteria, to disrupt epithelial gut wall integrity and promote their tissue invasion. We sought to develop a non-antibiotic-based approach to prevent this injury. Molecular docking studies suggested that glycosylated dendrimers block the TLR4-MD-2-LPS complex, and a 13.

Trypan blue dye enters viable cells incubated with the pore-forming toxin HlyII of Bacillus cereus.

Trypan blue is a dye that has been widely used for selective staining of dead tissues or cells. Here, we show that the pore-forming toxin HlyII of Bacillus cereus allows trypan blue staining of macrophage cells, despite the cells remaining viable and metabolically active. These findings suggest that the dye enters viable cells through the pores.

The Shigella flexneri type three secretion system effector IpgD inhibits T cell migration by manipulating host phosphoinositide metabolism.

Shigella, the Gram-negative enteroinvasive bacterium that causes shigellosis, relies on its type III secretion system (TTSS) and injected effectors to modulate host cell functions. However, consequences of the interaction between Shigella and lymphocytes have not been investigated. We show that Shigella invades activated human CD4(+) T lymphocytes.

Haemolysin II is a Bacillus cereus virulence factor that induces apoptosis of macrophages.

Bacillus cereus is a Gram-positive spore-forming bacterium causing food poisoning and serious opportunistic infections. These infections are characterized by bacterial accumulation despite the recruitment of phagocytic cells. The precise mechanisms and the bacterial factors allowing B.

Anthrax edema toxin modulates PKA- and CREB-dependent signaling in two phases.

Background: Anthrax edema toxin (EdTx) is an adenylate cyclase which operates in the perinuclear region of host cells. However, the action of EdTx is poorly understood, especially at molecular level. The ability of EdTx to modulate cAMP-dependent signaling was studied in Jurkat T cells and was compared with that of other cAMP-rising agents: Bordetella pertussis adenylate cyclase toxin, cholera toxin and forskolin.

cAMP imaging of cells treated with pertussis toxin, cholera toxin, and anthrax edema toxin.

The enzymatic activity of the three most studied bacterial toxins that increase the cytosolic cAMP level: pertussis toxin (PT), cholera toxin (CT), and anthrax edema toxin (ET), was imaged by fluorescence videomicroscopy. Three different cell lines were transfected with a fluorescence resonance energy transfer biosensor based on the PKA regulatory and catalytic subunits fused to CFP and YFP, respectively. Real-time imaging of cells expressing this cAMP biosensor provided time and space resolved pictures of the toxins action.

NADH oxidation drives respiratory Na+ transport in mitochondria from Yarrowia lipolytica.

It is generally assumed that respiratory complexes exclusively use protons to energize the inner mitochondrial membrane. Here we show that oxidation of NADH by submitochondrial particles (SMPs) from the yeast Yarrowia lipolytica is coupled to protonophore-resistant Na+ uptake, indicating that a redox-driven, primary Na+ pump is operative in the inner mitochondrial membrane. By purification and reconstitution into proteoliposomes, a respiratory NADH dehydrogenase was identified which coupled NADH-dependent reduction of ubiquinone (1.

Where and how do anthrax toxins exit endosomes to intoxicate host cells?

The role of Bacillus anthracis virulence factors in its pathogenesis has been subjected to intense investigation with the aim of finding novel preventive and therapeutic protocols. Toxins that are endocytosed and act in the cytosol of host cells have a central role in B. anthracis infection.

The concerted action of the Helicobacter pylori cytotoxin VacA and of the v-ATPase proton pump induces swelling of isolated endosomes.

The vacuolating cytotoxin (VacA) is a major virulence factor of Helicobacter pylori, the bacterium associated to gastroduodenal ulcers and stomach cancers. VacA induces formation of cellular vacuoles that originate from late endosomal compartments. VacA forms an anion-selective channel and its activity has been suggested to increase the osmotic pressure in the lumen of these acidic compartments, driving their swelling to vacuoles.

A vertebrate-type ferredoxin domain in the Na+-translocating NADH dehydrogenase from Vibrio cholerae.

The Na(+)-translocating NADH:quinone oxidoreductase from Vibrio cholerae contains a single Fe-S cluster localized in subunit NqrF. Here we study the electronic properties of the Fe-S center in a truncated version of the NqrF subunit comprising only its ferredoxin-like Fe-S domain. Mössbauer spectroscopy of the Fe-S domain in the oxidized state is consistent with a binuclear Fe-S cluster with tetrahedral sulfur coordination by the cysteine residues Cys(70), Cys(76), Cys(79), and Cys(111).