Solved by a verified expert:Assignment 8.1 – Host Defenses and
Virulence Factors
Name: Date:
1. Host Defenses
a. What are the two broadest
categories of host defense?
b. What are some of the innate or
non-specific defenses employed by the body?
c. What are some of the components
of the adaptive (specific) defenses?
2. Virulence Factors:
Exotoxins
a. What type of macromolecule is an
exotoxin?
b. What is a neurotoxin? Name one genus of bacteria that produces
neurotoxins.
c. What general area of the body do
enterotoxins affect?
d. What are cytotoxins?
e. How does the cytotoxin produced
by Corynebacterium diphtheriae affect
host cells?
f. What is the general description
of A-B toxins (in terms of the function of each subunit)?
g. How do membrane disrupting
toxins affect the host cell membrane?
h. Describe superantigens and their
effect on the body (in particular the immune system).
3. Virulence Factors:
Endotoxin
a. What are endotoxins?
b. How or when are endotoxins
released from the bacterial cell?
c. What intercellular signal is
released by macrophages following their ingestion of bacteria?
d. By what mechanism do endotoxins
cause fever?
e. How does the presence of
endotoxin lead to shock (dangerous drop in blood pressure)?
4. Virulence Factors:
Penetrating Host Tissues
a.
What is the enzyme name for the “spreading factor”streptococcal species
and Clostridium perfringensuse toinvade
host tissues?
b. What enzyme is used by some
streptococci and C. perfringens to
digest collagen?
c. What is streptokinase? How does this toxin work? What is another
name for streptokinase?
d. How is streptokinase and/or
staphylokinase activity advantageous to the pathogens that produce them?
5. Virulence Factors:
Hiding From Host Defenses
a. How do macrophages, B cells, and
T cells detect the presence of foreign cells?
b. How does the composition of the
bacterial capsule enable it to evade detection by immune cells such as
macrophages?
c. How does Mycobacterium tuberculosis survive being ingested by macrophages?
d. By what mechanism are Shigella and Listeria able to survive in macrophages following phagocytosis?
e. By what mechanism does Leishmania and Legionella survive within the phagolysosome (fused phagosome and
lysosome)?
f. What pathogens employ antigenic variation
to avoid detection by the immune system?
6. Virulence Factors:
Inactivating Host Defenses
a. What are peptidases?
b. What bacterium is capable of
producing a molecule that mimics complement, therefore preventing thiscascade
of immunological activity from occurring?
c. What are leukocidins? What species produce leukocidins?
d. How do IgA proteases aid the
species that produce them? Name one
species that produces this enzyme.
e. Describe one method by which HIV
suppresses the activity of the immune system.
f. What is the general definition
of a superantigen?
7. Virulence Factors:
Enteric Pathogens
a.
Name two examples of enteric pathogens.
b. By what methods is Salmonella able to inhibit phagocytosis?
c. What does Salmonella inject into host cells that causes actin rearrangement
and membrane ruffling? What is the
result of this activity?
d. How does the entry of Salmonella into host cells result in
diarrhea?
e. What type of cells must Shigella attach to for entry?
f. How does Shigella direct its entry into the host cell?
g. What is one other example of a
mechanism used by Shigella to spread
to neighboring cells?
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