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Bacterial InfectionsColonization of the Murine Oropharynx by Streptococcus pyogenes Is Governed by the Rgg2/3 Quorum Sensing SystemStreptococcus pyogenes is a human-restricted pathogen most often found in the human nasopharynx. Multiple bacterial factors are known to contribute to persistent colonization of this niche, and many are important in mucosal immunity and vaccine development. In this work, mice were infected intranasally with transcriptional regulator mutants of the Rgg2/3 quorum...
Molecular PathogenesisAntibody Binding and Complement-Mediated Killing of Invasive Haemophilus influenzae Isolates from Spain, Portugal, and the NetherlandsHaemophilus influenzae is a Gram-negative bacterium that can be classified into typeable (types a through f) and nontypeable (NTHi) groups. This opportunistic pathogen asymptomatically colonizes the mucosal epithelium of the upper respiratory tract, from where it spreads to other neighboring regions, potentially leading to disease. Infection with NTHi can cause otitis...
Host Response and InflammationLow-Avidity Autoantibodies against Bactericidal/Permeability-Increasing Protein Occur in Gram-Negative and Gram-Positive BacteremiaAntibody autoreactivity against bactericidal/permeability-increasing protein (BPI) is strongly associated with Pseudomonas aeruginosa infection in cystic fibrosis (CF), non-CF bronchiectasis (BE), and chronic obstructive pulmonary disease (COPD). We examined the pathogen-specific nature of this autoreactivity by examining antibodies to BPI in bacteremia patients....
Fungal and Parasitic InfectionsImportance of the Immunodominant CD8+ T Cell Epitope of Plasmodium berghei Circumsporozoite Protein in Parasite- and Vaccine-Induced ProtectionThe circumsporozoite protein (CSP) builds up the surface coat of sporozoites and is the leading malaria pre-erythrocytic-stage vaccine candidate. CSP has been shown to induce robust CD8+ T cell responses that are capable of eliminating developing parasites in hepatocytes, resulting in protective immunity. In this study, we characterized the importance of the immunodominant CSP-derived epitope SYIPSAEKI of...
Microbial Immunity and VaccinesComparative Study of Immunogenic Properties of Purified Capsular Polysaccharides from Streptococcus suis Serotypes 3, 7, 8, and 9: the Serotype 3 Polysaccharide Induces an Opsonizing IgG ResponseStreptococcus suis is an encapsulated bacterium and one of the most important swine pathogens and a zoonotic agent for which no effective vaccine exists. Bacterial capsular polysaccharides (CPSs) are poorly immunogenic, but anti-CPS antibodies are essential to the host defense against encapsulated bacteria. In addition to the previously known serotypes 2 and 14, which...
Bacterial InfectionsLeukocidins and the Nuclease Nuc Prevent Neutrophil-Mediated Killing of Staphylococcus aureus BiofilmsBacterial biofilms are linked with chronic infections and have properties distinct from those of planktonic, single-celled bacteria. The virulence mechanisms associated with Staphylococcus aureus biofilms are becoming better understood. Human neutrophils are critical for the innate immune response to S....
Bacterial InfectionsGenome-Wide Assessment of Streptococcus agalactiae Genes Required for Survival in Human Whole Blood and PlasmaStreptococcus agalactiae (group B streptococcus, or GBS) is a common cause of bacteremia and sepsis in newborns, pregnant women, and immunocompromised patients. The molecular mechanisms used by GBS to survive and proliferate in blood are not well understood. Here, using a highly virulent GBS strain and transposon-directed insertion site sequencing (TraDIS), we...
Host Response and Inflammation | SpotlightGroup A Streptococcus Infection of the Nasopharynx Requires Proinflammatory Signaling through the Interleukin-1 ReceptorGroup A Streptococcus (GAS) is the etiologic agent of numerous high-morbidity and high-mortality diseases. Infections are typically highly proinflammatory. During the invasive infection necrotizing fasciitis, this is in part due to the GAS protease SpeB directly activating interleukin-1β (IL-1β) independent of the canonical inflammasome pathway. The upper respiratory tract is the primary site for GAS colonization, infection,...
Host Response and Inflammation | SpotlightDifferential Induction of Type I and III Interferons by Staphylococcus aureusStaphylococcus aureus is a leading cause of bacterial pneumonia, and we have shown previously that type I interferon (IFN) contributes to the pathogenesis of this disease. In this study, we screened 75 S. aureus strains for their ability to induce type I and III IFN. Both cytokine pathways were...
