Spotlight
Molecular Pathogenesis
Molecular PathogenesisAtypical Hemolytic Listeria innocua Isolates Are Virulent, albeit Less than Listeria monocytogenesListeria innocua is considered a nonpathogenic Listeria species. Natural atypical hemolytic L. innocua isolates have been reported but have not been characterized in detail.
Molecular PathogenesisShiga Toxin Type 1a (Stx1a) Reduces the Toxicity of the More Potent Stx2a In Vivo and In VitroShiga toxin (Stx)-producing Escherichia coli (STEC) causes foodborne outbreaks of bloody diarrhea. There are two major types of immunologically distinct Stxs: Stx1a and Stx2a.
Molecular PathogenesisContributions of TolC Orthologs to Francisella tularensis Schu S4 Multidrug Resistance, Modulation of Host Cell Responses, and VirulenceFrancisella tularensis is a Gram-negative, facultative intracellular pathogen and the causative agent of tularemia. Previous studies with the attenuated live vaccine strain (LVS) identified a role for the outer membrane protein TolC in modulation of host cell responses during infection and virulence in the mouse model of tularemia.
Molecular PathogenesisStructural and Functional Insights into PpgL, a Metal-Independent β-Propeller Gluconolactonase That Contributes to Pseudomonas aeruginosa VirulenceBiofilm formation is a critical determinant in the pathopoiesis of Pseudomonas aeruginosa. It could significantly increase bacterial resistance to drugs and host defense.
Cellular Microbiology: Pathogen-Host Cell Molecular Interactions
Cellular Microbiology: Pathogen-Host Cell Molecular Interactions2-Hydroxylation of Acinetobacter baumannii Lipid A Contributes to VirulenceAcinetobacter baumannii causes a wide range of nosocomial infections. This pathogen is considered a threat to human health due to the increasingly frequent isolation of multidrug-resistant strains.
Cellular Microbiology: Pathogen-Host Cell Molecular InteractionsStaphylococcus aureus Biofilm-Conditioned Medium Impairs Macrophage-Mediated Antibiofilm Immune Response by Upregulating KLF2 ExpressionStaphylococcus aureus infections associated with the formation of biofilms on medical implants or host tissue play a critical role in the persistence of chronic infections. One critical mechanism of biofilm infection that leads to persistent infection lies in the capacity of biofilms to evade the macrophage-mediated innate immune response.
Cellular Microbiology: Pathogen-Host Cell Molecular InteractionsInteraction of Gardnerella vaginalis and Vaginolysin with the Apical versus Basolateral Face of a Three-Dimensional Model of Vaginal EpitheliumStudies have implicated Gardnerella vaginalis as an important etiological agent in bacterial vaginosis (BV). It produces a cholesterol-dependent cytolysin, vaginolysin (VLY).
Cellular Microbiology: Pathogen-Host Cell Molecular Interactions | SpotlightHuman Intestinal Enteroids as a Model System of Shigella PathogenesisThe enteric bacterium and intracellular human pathogen Shigella causes hundreds of millions of cases of the diarrheal disease shigellosis per year worldwide. Shigella is acquired by ingestion of contaminated food or water; upon reaching the colon, the bacteria invade colonic epithelial cells, replicate intracellularly, spread to adjacent cells, and provoke an intense inflammatory response.
Cellular Microbiology: Pathogen-Host Cell Molecular Interactions | SpotlightIntracellular Degradation of Helicobacter pylori VacA Toxin as a Determinant of Gastric Epithelial Cell ViabilityHelicobacter pylori VacA is a secreted pore-forming toxin that induces cell vacuolation in vitro and contributes to the pathogenesis of gastric cancer and peptic ulcer disease. We observed that purified VacA has relatively little effect on the viability of AGS gastric epithelial cells, but the presence of exogenous weak bases such as ammonium chloride (NH...
Bacterial Infections
Bacterial InfectionsGenetic Variation/Evolution and Differential Host Responses Resulting from In-Patient Adaptation of Mycobacterium avium...Members of the Mycobacterium avium complex (MAC) are characterized as nontuberculosis mycobacteria and are pathogenic mainly in immunocompromised individuals. MAC strains show a wide genetic variability, and there is growing evidence suggesting that genetic differences may contribute to a varied immune response that may impact the infection outcome.
Bacterial InfectionsThe Porphyromonas gingivalis Hybrid Cluster Protein Hcp Is Required for Growth with Nitrite and Survival with Host CellsAlthough the periodontal pathogen Porphyromonas gingivalis must withstand high levels of nitrosative stress while in the oral cavity, the mechanisms of nitrosative stress defense are not well understood in this organism. Previously we showed that the transcriptional regulator HcpR plays a significant role in defense, and here we further defined its regulon.
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Bacterial InfectionsPotential Therapeutic Effects of Mepacrine against Clostridium perfringens Enterotoxin in a Mouse Model of Enterotoxemia...Clostridium perfringens enterotoxin (CPE) is a pore-forming toxin that causes the symptoms of common bacterial food poisoning and several non-foodborne human gastrointestinal diseases, including antibiotic-associated diarrhea and sporadic diarrhea. In some cases, CPE-mediated disease can be very severe or fatal due to the involvement of enterotoxemia.
Bacterial InfectionsVirulence Traits of a Serogroup C Meningococcus and Isogenic cssA Mutant, Defective in Surface-Exposed Sialic Acid, in a Murine Model of MeningitisIn serogroup C Neisseria meningitidis, the cssA (siaA) gene codes for an UDP-N-acetylglucosamine 2-epimerase that catalyzes the conversion of UDP-N-acetyl-α-d-glucosamine into N-acetyl-d-mannosamine and UDP in the first step in sialic acid biosynthesis. This enzyme is required...
Bacterial Infections | SpotlightEvaluating Shigella flexneri Pathogenesis in the Human Enteroid ModelThe enteric pathogen Shigella is one of the leading causes of moderate-to-severe diarrhea and death in young children in developing countries. Transformed cell lines and animal models have been widely used to study Shigella pathogenesis.
Bacterial InfectionsContribution of Active Iron Uptake to Acinetobacter baumannii PathogenicityAcinetobacter baumannii is an important nosocomial pathogen. Mechanisms that allow A. baumannii to cause human infection are still poorly understood.
Bacterial InfectionsPorcine Gastric Mucin Triggers Toxin Production of Enteropathogenic Bacillus cereusEnteropathogenic Bacillus cereus causes foodborne infections due to the production of pore-forming enterotoxins in the intestine. Before that, spores have to be ingested, survive the stomach passage, and germinate.
Bacterial InfectionsSpotted Fever Group Rickettsia Infection and Transmission Dynamics in Amblyomma maculatumTick vectors are capable of transmitting several rickettsial species to vertebrate hosts, resulting in various levels of disease. Studies have demonstrated the transmissibility of both rickettsial pathogens and novel Rickettsia species or strains with unknown pathogenicity to vertebrate hosts during tick blood meal acquisition; however, the quantitative nature of transmission remains unknown.
Bacterial InfectionsArtificial Selection for Pathogenicity Mutations in Staphylococcus aureus Identifies Novel Factors Relevant to Chronic InfectionAdaptation of Staphylococcus aureus to host microenvironments during chronic infection involves spontaneous mutations, yet changes underlying adaptive phenotypes remain incompletely explored. Here, we employed artificial selection and whole-genome sequencing to better characterize spontaneous chromosomal mutations that alter two pathogenicity phenotypes relevant to...
Bacterial InfectionsRedundant and Distinct Roles of Secreted Protein Eap and Cell Wall-Anchored Protein SasG in Biofilm Formation and Pathogenicity of Staphylococcus aureusChronic and fatal infections caused by Staphylococcus aureus are sometimes associated with biofilm formation. Secreted proteins and cell wall-anchored proteins (CWAPs) are important for the development of polysaccharide-independent biofilms, but functional relationships between these proteins are unclear.
Host Response and Inflammation
Host Response and InflammationIdentification of a Conserved, Orphan G Protein-Coupled Receptor Required for Efficient Pathogen Clearance in Caenorhabditis elegansG protein-coupled receptors contribute to host defense across the animal kingdom, transducing many signals involved in both vertebrate and invertebrate immune responses. While it has become well established that the nematode worm Caenorhabditis elegans triggers innate immune responses following infection with numerous bacterial, fungal, and viral pathogens, the...
Host Response and InflammationYersinia pestis Exploits Early Activation of MyD88 for Growth in the Lungs during Pneumonic PlagueYersinia pestis causes bubonic, pneumonic, and septicemic plague. Although no longer responsible for pandemic outbreaks, pneumonic plague continues to be a challenge for medical treatment and has been classified as a reemerging disease in some parts of the world.
Host Response and InflammationImmunological Responses to the Relapsing Fever Spirochete Borrelia turicatae in Infected Rhesus Macaques: Implications for Pathogenesis and DiagnosisThe global public health impact of relapsing fever (RF) spirochetosis is significant, since the pathogens exist on five of seven continents. The hallmark sign of infection is episodic fever and the greatest threat is to the unborn.
Fungal and Parasitic Infections
Fungal and Parasitic InfectionsKinetic and Cross-Sectional Studies on the Genesis of Hypoargininemia in Severe Pediatric Plasmodium falciparum MalariaThe low bioavailability of nitric oxide (NO) and its precursor, arginine, contributes to the microvascular pathophysiology of severe falciparum malaria. To better characterize the mechanisms underlying hypoargininemia in severe malaria, we measured the plasma concentrations of amino acids involved in de novo arginine synthesis in children with uncomplicated falciparum malaria (UM; n = 61), children with cerebral...
Fungal and Parasitic Infections | SpotlightTalaromyces marneffei Mp1 Protein, a Novel Virulence Factor, Carries Two Arachidonic Acid-Binding Domains To Suppress Inflammatory Responses in HostsTalaromyces marneffei infection causes talaromycosis (previously known as penicilliosis), a very important opportunistic systematic mycosis in immunocompromised patients. Different virulence mechanisms in T. marneffei have been proposed and investigated.
Fungal and Parasitic InfectionsInduction of Inflammatory Responses in Splenocytes by Exosomes Released from Intestinal Epithelial Cells following Cryptosporidium parvum InfectionCryptosporidium, a protozoan parasite that infects the gastrointestinal epithelium and other mucosal surfaces in humans and animals, is an important opportunistic pathogen in AIDS patients and one of the most common enteric pathogens affecting young children in developing regions. This parasite is referred to as a “minimally invasive” mucosal pathogen, and epithelial cells play a central role in activating and orchestrating...
Fungal and Parasitic Infections | SpotlightA Glucuronoxylomannan Epitope Exhibits Serotype-Specific Accessibility and Redistributes towards the Capsule Surface during Titanization of the Fungal Pathogen Cryptococcus neoformansDisseminated infections with the fungal species Cryptococcus neoformans or, less frequently, Cryptococcus gattii are an important cause of mortality in immunocompromised individuals. Central to the virulence of both species is an elaborate polysaccharide capsule that consists predominantly of...
Fungal and Parasitic InfectionsToll-Like Receptor 3–TRIF Pathway Activation by Neospora caninum RNA Enhances Infection Control in MiceNeospora caninum is a protozoan parasite closely related to Toxoplasma gondii and has been studied for causing neuromuscular disease in dogs and abortions in cattle. It is recognized as one of the main transmissible causes of reproductive failure in cattle and consequent economic losses to the...
Fungal and Parasitic InfectionsHookworm-Derived Metabolites Suppress Pathology in a Mouse Model of Colitis and Inhibit Secretion of Key Inflammatory Cytokines in Primary Human LeukocytesIatrogenic hookworm therapy shows promise for treating disorders that result from a dysregulated immune system, including inflammatory bowel disease (IBD). Using a murine model of trinitrobenzenesulfonic acid-induced colitis and human peripheral blood mononuclear cells, we demonstrated that low-molecular-weight metabolites derived from both somatic extracts (LMWM-SE) and excretory-secretory products (LMWM-ESP) of the hookworm,...
Microbial Immunity and Vaccines
Microbial Immunity and VaccinesModerately Neutralizing Epitopes in Nonfunctional Regions Dominate the Antibody Response to Plasmodium falciparum EBA-140Plasmodium falciparum erythrocyte-binding antigen 140 (EBA-140) plays a role in tight junction formation during parasite invasion of red blood cells and is a potential vaccine candidate for malaria. Individuals in areas where malaria is endemic possess EBA-140-specific antibodies, and individuals with high antibody titers to this protein have a lower rate of...
Host-Associated Microbial Communities
Host-Associated Microbial Communities | SpotlightHost-Derived Metabolites Modulate Transcription of Salmonella Genes Involved in l-Lactate Utilization during Gut ColonizationDuring Salmonella enterica serovar Typhimurium infection, host inflammation alters the metabolic environment of the gut lumen to favor the outgrowth of the pathogen at the expense of the microbiota. Inflammation-driven changes in host cell metabolism lead to the release of l-lactate and molecular oxygen from the tissue into the gut lumen.
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Infection and Immunity® (IAI) reports key discoveries that help microbiologists, immunologists, epidemiologists, pathologists, and clinicians to gain new insights into the underlying mechanisms of host-pathogen interactions and develop novel strategies to prevent or treat infectious diseases.