neisseria, mycobacterium, bacteriophage + microbiome

Neisseria info

Gram-negative cocci, often diplococci, that use type IV pili for twitching motility and are naturally competent.

Neisseria disease

causes meningitis or gonorrhea

Neisseria human impact

major public health importance, resistant + reproductive complications

Neisseria function

depends on pili, Opa proteins, LOS, complement evasion, and extensive phase and antigenic variation. Invasive meningococci usually have a capsule, while gonococci rely heavily on surface variation and immune evasion

Neisseria host rxn

inflammation and mucosal immune activation, though immune evasion strategies can make reinfection and persistence easier

Neisseria paper

examined how commensal Neisseria release peptidoglycan fragments and how those fragments affect host immune sensing

Neisseria big question

how different Neisseria strains release peptidoglycan fragments and how those fragments influence NOD1/NOD2 activation

Neisseria solution

authors used metabolic labeling, chromatography, scintillation counting, and reporter assays to compare the inflammatory cell wall products released by different strains.

mycobacterium info

acid-fast, slow-growing intracellular bacteria with mycolic acid-rich cell walls.

mycobacterium disease

causes leprosy, a chronic infection w/ nerve and skin damage and tuberculosis, major global infectious killer

mycobacterium human impact

causes long term disease + requires special immune control

myco function

 Mycobacterium tuberculosis survives in macrophages, blocks phagosome-lysosome fusion, uses lipids such as PDIM and PGL, and relies on factors like ESX-1 instead of classic toxins. Granuloma formation is a key feature of TB pathogenesis

myco host rxn

 macrophage activation, T-cell responses, granuloma formation, and long-term latent infection

myco paper

whether bacteriophages can enter mammalian cells and kill intracellular mycobacteria

myco big question

whether phages can enter mammalian cells and reduce intracellular mycobacterial burden

myco solution

authors used fluorescence microscopy, reporter phages, electron microscopy, and intracellular burden assays to show that phages can access intracellular bacteria

bacteriophage info

 viruses that infect bacteria. They can follow lytic or lysogenic life cycles

bacteriophage disease

bacteriophage function

Lytic phages kill bacteria directly, while lysogenic phages can persist in the host genome. Host range depends on receptor recognition, and bacteria counter phages using restriction systems, CRISPR-Cas, and other defenses

bacteriophage human impact

bacteriophage host rxn

bacteriophage paper

phage communication during lysogeny

bacteriophage big question

whether lysogens continue to communicate using arbitrium and use that signal to regulate exit from lysogeny

bacteriophage solution

 authors used gene-expression assays, signaling perturbation, DNA-damage induction, and reporter systems to show that lysogens continue to signal and that the signal represses induction when lysogens are abundant

microbiome info

community of microorganisms, helps maintain a healthy state, supports colonization resistance & affects immunity, mucosal barriers + inflammation

microbiome disease

gastrointestinal disease, inflammation, bacterial vaginosis + increase for infection

possible obesity, diabetes, colorectal cancer, crohns disease + gastroenteritis

microbiome human impact

broad because it influences colonization resistance, barrier function, metabolism, and immune education

microbiome function

competing for nutrients and niches, producing metabolites such as short-chain fatty acids, supporting mucin and barrier function, and shaping host defenses like antimicrobial peptides and IgA

microbiome host rxn

tightly linked to microbiome state: a healthy microbiome supports homeostasis, while disturbed communities can contribute to inflammation and infection susceptibility

microbiome paper

asked whether a major gut commensal changes Shigella virulence

microbiome big question

whether Bacteroides thetaiotaomicron can directly change Shigella virulence

microbiome solution

authors used conditioned medium, invasion assays, plaque assays, protein detection, gene-expression assays, and fractionation to show that outer membrane vesicles from B. thetaiotaomicron repress Shigella virulence