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Bacteria II
Virulence Factors
35
Microbiology
Graduate
09/30/2009
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Term
Bordetella
 Definition
Filamentous Hemagglutinin (FHA) and pertactin; Pertussis toxin (PT) – A-B toxin; Adenylate cyclase/hemolysin; Tracheal cytotoxin (TC)
Term
Neisseria general
 Definition
pili: potential to produce genetically different pilin molecules (antigenic variation)
Endotoxin: Lipooligosaccharide (LOS) – Lipid A plus core polysaccharide by no O-antigen
IgA1 protease
Iron acquisition through surface receptors
Outer membrane proteins
•PorA and PorB (porin protein): prevents phagolysosome fusion – antigenic variation
•Rmp (reduction-modifiable protein): binds IgG and blocks other antibodies from binding: protects other surface antigens from bactericidal antibodies
Term
N. gonorrhoeae
 Definition
 Outer membrane protein
• Opa (opacity protein): mediates firm attachment to epithelial cells and subsequent invasion
Term
N. meningitides
 Definition
 polysaccharide capsule
• 14 different capsular polysaccharides serogroups: most infections are A, B, C, Y and W135
Term
General Enterobacteriacea
 Definition
 endotoxin
 capsule or slime laye
 antigenic phase variation: ability to express or not express K (capsular) and H (flagellar) antigens
 Type III secretion systems: inject virulence factors into host cells
 sequestration of growth factors: iron
 resistance to serum killing: prevent binding of complement
 antimicrobial resistance
Term
Escherichia general
 Definition
 adherence factors
 exotoxins
 3 antigens (i.e. O157:H7 – causes hemorrhagic colitis)
• O antigen: polysaccharide of LPS; heat-stable
• H antigen: associated with flagella
• K antigen: assoc. with capsule
Term
ETEC
 Definition
• Heat-labile toxin (LT-I) – two-component A-B): increase in cAMP leads to secretion
• Heat-stable toxin (STa): increase in cGMP leads to secretion
Term
EPEC
 Definition
• Destruction of microvilli: disrupts absorptive functions
• no toxin produced
Term
EAEC
 Definition
• Aggregate adherence fimbriae – biofilm (protects from antibiotics and phagocytes)
• Enteroaggregative heat stable toxin (EAST) and Plasmid encoded toxin (PET): fluid secretion
Term
EHEC
 Definition
• Shiga-like toxin (two-component A-B): stops protein synthesis
Term
EIEC
 Definition
• penetrates epithelial lining of large intestine
• invasion and survival in intestinal epitheliapushes into other cells
Term
Salmonella general
 Definition
 invade and replicate in enterocytes and M cells
Term
S. typhi
 Definition
• catalase, superoxide dismutase
Term
Shigella
 Definition
• invades and replicated in cells lining the colon
o cell-to-cell passage, evades immune system
• Shiga toxin: prevents protein synthesis
Term
Yersinia
 Definition
 Resist phagocytic killing
• Type III secretion system injects proteins into phagocytes that prevent phagocytes that prevent phagocytosis and induce apoptosis
 Degrade complement components
Term
Vibrio spp.
 Definition
adherence factors
Term
V. cholera
 Definition
 Cholera toxin (O1 and O139)
• two-component A-B toxin that casuse increased levels of cAMPhypersecretion
Term
Aeromonas
 Definition
 hemolysins, heat-labile, and heat stable enterotoxins
Term
Camphylobacter
 Definition
 invasion into intestinal tissue
Term
Helicobacter
 Definition
 colonization of gastric mucosabacterial protein blocks acid production and urease created ammonia which neutralizes gastric acidsadherence to epithelial cellsdestruction of mucous-producing gastric cells by ammonia, cytotoxin, and enzymesulceration by stomach acid
Term
Pseudomonas
 Definition
o attachment and colonization of host tissue
 pili and capsule
o produces exotoxins
 exotoxin A prevents protein synthesis (two-component A-B)
 exoenzymes S and T: cytotoxic
o Produces hemolysins and variety of degradation enzymes
 tissue and Ig destruction
Term
Haemophilus
 Definition
o Capsule – 6 subtypes (a-f)
o IgA protease
Term
Francisella tularensis
 Definition
Intracellular pathogen: Survives in macrophage, prevents phagosome-lysosome fusion, prevents phagosome acidification; Capsule: Loss of capsule associated with decreased virulence
Term
Brucella melitensis
 Definition
Intracellular pathogen: Survives in macrophage, prevents phagosome-lysosome fusion, prevents release of toxic enzymes, catalase and superoxide dismutase; dissemination: Granuloma formation, tissue destruction
Term
Legionella pneumophila
 Definition
 URT to lung
 outermembrane protein binds a complement component (phagocyte recognition)
 macrophage invasion potentiator assists in cell entry
 prevents phagosome-lysosome fusion
 inhibits killing mechanisms of macrophage
Term
C. perfringens
 Definition
 5 major toxins
• Alpha toxin (phospholipase C): lecithinase = hemolysis: RBCs, WBCs, muscle cells
• Beta toxin: necrotic lesions
• Epsilon toxin: increases vascular permeability
• Iota toxin: necrosis
• Enterotoxin: inserts in cell membrane = fluid and ion loss (superantigen)
 Six minor toxins:
• Theta toxin: hemolysin (RBCs) = decrease in O2
Term
C. difficile
 Definition
 Enterotoxin (toxin A)
• stimulates PMN infiltration into ileum
• disrupts intracellular tight junctions
• altered membrane permeability and fluid secretion
 Cytotoxin (toxin B)
 Mode of infection: antibiotic therapy destroys other normal flora allowing overgrowth (or exogenous acquisition)toxins producedleukocyte infiltration into colon
Term
C. tetani
 Definition
 hemolysin: tenanolysin
 neurotoxin: tetanospasmin
• accounts for classic symptoms
• acts on neurons in spinal cord by blocking release of inhibitory neurotransmitters resulting in unrestrained excitation of motor neuronsspastic paralysis
Term
C. botulinum
 Definition
 neurotoxins A, B, E and F cause human disease
• bind with proteins that protect them in digestive tract
• enter the blood, carried to peripheral nerve, bind to receptor sites at neuromuscular junction
• inhibits ACh release (NM receptor)
• flaccid paralysis
Term
Trepenoma pallidum
 Definition
 little known
 few if any proteins exposed
 adherence to host cell fibronectin
 possible hemolysins
Term
B. recurrentis
 Definition
 changes surface protein antigens: antigenic variation (reason behind cyclical relapsing fevers)
Term
Mycoplasma pneumoniae
 Definition
membrane-associated protein P1: binds sialic acid glycolipis on host cell membranes, affinity for ciliated bronchila epithelial cells, inhibits ciliary, inflammatory response develops in bronchial tissues
Term
Rickettsia
 Definition
induced phagocytosis, phospholipase-mediated phagosome escape (spotted fever group-projections, typhus-lysis), leakage of blood into tissues, organ and tissue damage
Term
Ehrlichia and Anaplasma
 Definition
infection of leukocytes via phagocytosis; small, dense-cored (DC) cells (0.2-0.4 micro) bind cells and induce uptake; inhibiiton of phago-lyso fusion; DCs transitions to larger (0.8-1.5 micro)reticulate cells (RCs) which replicate
Term
Coxiella burnetti
 Definition
intracellular bacteria (cytoplasmic vacuoles); survival in phagolysosomes (low pH tolerant and resistant to enzymes); lysis of cell; phase variation in LPS: acute (antibodies to phase II) and chronic (antibodies to phase I and II)
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