Virulence Factors

Question 1

Escherichia Coli Virulence Factors (Exotoxins)

Answer 1

Heat-labile
Heat-stable
Shiga Toxins

Question 2

Heat-labile (E. coli)

Answer 2

Stimulate adenylate cylase in epithelial cells of dmsll intestine
Increases permeability of intestinal wall resulting in fluid loss and diarrhea

Question 3

Heat-stable (E. coli)

Answer 3

Impairs net chloride and sodium absorption
Activates guanylate cyclase leads to increase lvl of cyclic guanosine monophosphate and subsequen hypersecretion of fluids

Question 4

Shiga Toxins (E. coli)

Answer 4

AB toxin that disrupts protein synthesis in intestinal epithelial cells leading to destruction of intestinal cillus and decreased absorption and increase fluid secretion

Question 5

Escherichia Coli Virulence Factors

Answer 5

Adhesions (able to colonize urinary and GI tract and avoid flushing)
Endotoxin
Capsule

Question 6

Salmonella Virulence Factors

Answer 6

Vi antigen (capsular antigen of S. Typhi that prevents phagocytosis by host)
Pathogenicity islands (mobile genetic element, encode T3SS invasiveness)
Intracellular survival and escape (survives in macrophages and can spread from intestine to other parts)
Endotoxin (important in bacteremia)
Acid tolerance
Plasmid encoded virulence (varies with serotype, serum resistance, iron acquisition, fimbriae)

Question 7

Shigella Virulence Factors

Answer 7

Endotoxin
Invasiveness
Virulence plasmids encode various gene but ar chromosomally regulated
Shiga Toxin (Enterotxin-diarrhea, Cytotoxic inhibits protein synthesis-colonic ulcers)

Question 8

Yersinia Virulence Factors

Answer 8

Endotoxin
Serum resistance
Multiple virulence plasmids (T3SS, F1 antigen, Attachment, Intracellular survival, Siderophore)

Question 9

Neisseria Meningitidis Virulence Factors

Answer 9

Capsule (Antiphagocytic- 12 serogroups A B C H I K L W-135 X Y Z 29E with ABC most common)
Pili (Adhere to nasopharynx)
IgA (Cleaves IgA in mucus to help mucosal survival on surfaces)
Endotoxin (Lipid A portion of LOS- lipoologosaccharide lipid A and core oligosaccharide, no O polysaccharide)

Question 10

Neisseria Gonorrhoeae Virulence Factors

Answer 10

Antiphagocytic capsule like neg surface charge - no true capsule
Pilus (adherence, resistance to phagocytosis, antigenic variation)
Outer membrane proteins (Por, Opa, Rmp)
Iron Acqusition: Tbp 1/2 (transferrin binding proteins)
Lbp (lactoferrin binding proteins)
Hbp (Hemoglobin binding proteins)
IgAprotease
Antibiotic resistance (Plasmid mediated beta-lactamase production, chromosomally mediated cellular changes in permeability to inhibit entry of penicillins tetracycline erthromycin and aminoglycosides)

Question 11

Por

Answer 11

Porin protein prevents phagolysosome fusion following phagocytosis and promotes intracellular survival

Question 12

Opa

Answer 12

Opacity protein mediates firm attachment to epithelial cells and subsequent invasion into cells

Question 13

Rmp

Answer 13

Reduction modifiable protein protects other surface antigens from bacterial antibodies

Question 14

Vibrio Cholerae Virulence Factors

Answer 14

Enterotoxin (Cholera AB toxin)
Phage mediated
Normally, net flow of water across intestinal mucosa is from lumen to tissue
Toxin alters electrolyte balance in mucosa from tissue to lumen
B binds to cell receptor
A enters the cell
Stimulates adenylate cyclase activation
Causes hypersecretion of Na, Cl, K, HCO3

Question 15

Aeromonas Virulence Factors

Answer 15

Endotoxin
Hemolysins
Enterotoxins
Adherence factors

Question 16

Campylobacter Virulence Factors

Answer 16

Not understood
Endotoxins
Enterotoxins
Cytopathic toxins (Produce histopathological damage to mucosal surfaces of jejunum, ileum, and colon)
Likely plasmid mediated adhesion and invasion by T4SS
S-protein of C. fetus resistance to complement mediated and Ab mediated killing, important for systemic disease