Nuclear factor kappa B-dependent persistence of Typhi and Paratyphi in human macrophages.

Unlabelled: serovars Typhi and Paratyphi cause a prolonged illness known as enteric fever, whereas other serovars cause acute gastroenteritis. Mechanisms responsible for the divergent clinical manifestations of nontyphoidal and enteric fever infections have remained elusive. Here, we show that .

Scratching the Surface Takes a Toll: Immune Recognition of Viral Proteins by Surface Toll-like Receptors.

Early innate viral recognition by the host is critical for the rapid response and subsequent clearance of an infection. Innate immune cells patrol sites of infection to detect and respond to invading microorganisms including viruses. Surface Toll-like receptors (TLRs) are a group of pattern recognition receptors (PRRs) that can be activated by viruses even before the host cell becomes infected.

The Accessory Gene of the SaeR/S Two-Component Gene Regulatory System Impacts Virulence During Neutrophil Interaction.

() causes a range of diseases ranging from superficial skin and soft-tissue infections to invasive and life-threatening conditions (Klevens et al., 2007; Kobayashi et al., 2015).

Quantifying the Cytotoxicity of Staphyloccus aureus Against Human Polymorphonuclear Leukocytes.

Staphylococcus aureus is capable of secreting a wide range of leukocidins that target and disrupt the membrane integrity of polymorphonuclear leukocytes (PMNs or neutrophils). This protocol describes both the purification of human PMNs and the quantification of S. aureus cytotoxicity against PMNs in three different sections.

Aspartic Acid Residue 51 of SaeR Is Essential for Virulence.

is a common Gram-positive bacteria that is a major cause of human morbidity and mortality. The SaeR/S two-component sensory system of is important for virulence gene transcription and pathogenesis. However, the influence of SaeR phosphorylation on virulence gene transcription is not clear.

Staphylococcus aureus SaeR/S-Regulated Factors Decrease Monocyte-Derived Tumor Necrosis Factor-α to Reduce Neutrophil Bactericidal Activity.

Background: The ability of Staphylococcus aureus to evade killing by human neutrophils significantly contributes to disease progression. In this study, we characterize an influential role for the S. aureus SaeR/S 2-component gene regulatory system in suppressing monocyte production of tumor necrosis factor alpha (TNF-α) to subsequently influence human neutrophil priming.

Immune evasion by a staphylococcal inhibitor of myeloperoxidase.

is highly adapted to its host and has evolved many strategies to resist opsonization and phagocytosis. Even after uptake by neutrophils, shows resistance to killing, which suggests the presence of phagosomal immune evasion molecules. With the aid of secretome phage display, we identified a highly conserved protein that specifically binds and inhibits human myeloperoxidase (MPO), a major player in the oxidative defense of neutrophils.

Epic Immune Battles of History: Neutrophils vs. .

Neutrophils are the most abundant leukocytes in human blood and the first line of defense after bacteria have breached the epithelial barriers. After migration to a site of infection, neutrophils engage and expose invading microorganisms to antimicrobial peptides and proteins, as well as reactive oxygen species, as part of their bactericidal arsenal. Ideally, neutrophils ingest bacteria to prevent damage to surrounding cells and tissues, kill invading microorganisms with antimicrobial mechanisms, undergo programmed cell death to minimize inflammation, and are cleared away by macrophages.

Increased Pilus Production Conferred by a Naturally Occurring Mutation Alters Host-Pathogen Interaction in Favor of Carriage in Streptococcus pyogenes.

Studies of the human pathogen group A (GAS) define the carrier phenotype to be an increased ability to adhere to and persist on epithelial surfaces and a decreased ability to cause disease. We tested the hypothesis that a single amino acid change (Arg135Gly) in a highly conserved sensor kinase (LiaS) of a poorly defined GAS regulatory system contributes to a carrier phenotype through increased pilus production. When introduced into an serotype-matched invasive strain, the carrier allele (the gene encoding the LiaS protein with an arginine-to-glycine change at position 135 []) recapitulated a carrier phenotype defined by an increased ability to adhere to mucosal surfaces and a decreased ability to cause disease.

Staphylococcus aureus SaeR/S-regulated factors reduce human neutrophil reactive oxygen species production.

Neutrophils are the first line of defense after a pathogen has breached the epithelial barriers, and unimpaired neutrophil functions are essential to clear infections. Staphylococcus aureus is a prevalent human pathogen that is able to withstand neutrophil killing, yet the mechanisms used by S. aureus to inhibit neutrophil clearance remain incompletely defined.