Practice Final Exam Questions: For the lectures from Salmonella through Bordetella.
Practice questions for Pseudomonas and Helicobacter will be posted next week.
1.
Name 2 surface antigens of the genus Salmonella that serve to distinguish serotypes
based upon antigenicity?
2.
Describe what Jorge Galan observed following the interaction of virulent
Salmonella with polarized MDCK cells? What genes are involved with this
pathogenetic interaction?
3.
List 4 features of a pathogenicity island?
4.
The “type three secretion system” of Salmonella’s pathogenicity island 1 functions
to deliver several bacterial effector proteins that effect host cell physiology. Name
and describe 2 of these effector proteins, how they get into the host cell, their
function within the host cell, and what benefit do these effector proteins provide to
Salmonella?
5.
What benefit does the condition of diarrhea provide to Salmonella during its
pathogenesis? How does Salmonella induce this condition?
6.
Describe the experiment by Chen that showed that internalization was not required
for the induction of macrophage apoptosis by Salmonella.
7.
Many Salmonella virulence genes are controlled by the two-component regulatory
system PhoP/PhoQ. Genes that are positively regulated by this system are called
pag and those negatively regulated or repressed by this system are called prg. In the
study by Miller et al., pag and prg genes where constructed with a reporter system
to identify expression within macrophages and epithelial cells. What were the
findings and conclusions of this study?
8.
In the Salmonella macrophage infection study by Rathman, fluorescent labled
antibodies directed against markers specific to the various stages of the endocytotic
degradative pathway were utilized following infection of macrophages with wild
type Salmonella, invasion mutants of Salmonella, heat-killed Salmonella, and latex
beads. What were the conclusions based upon the data from this experiment?
9.
In the above question #8, what role does Salmonella pathogenicity island 2 play in
this mechanism?
10. What unique cell wall associated feature does Listeria monocytogenes possess that
is not found associated with the cell walls of other gram positive bacteria?
11. Listeria monocytogenes is an intracellular pathogen that is capable of multiplying
inside resting macrophages. How does Listeria avoid the phagolysosomal killing
mechanism of this phagocytic cell?
12. In the study conducted by Bielecki et al., the hlyA gene of L. monocytogenes that
encodes listeriolysin O was mutated. Describe how this gene was mutated, the
resulting 2 phenotypes that were looked at following mutation, and the conclusions
based upon these data.
13. Listeriolysin O is a member of a family that contains several other cholesteroldependent cytolysins secreted by gram positive pathogens. However, Listeriolysin
O is the only one that functions within the vacuole whereas these other cytolysins
function extracellularly. Name 2 properties of Listeriolysin O that are different
from the properties of these other cytolysins and how is this important to successful
Listeria pathogenesis?
14. Kocks et al. compared macrophage infection using wild type Listeria, Listeria with
a transposon mutation of the hlyA gene, wild type Bacillus subtilis, and a B. subtilis
strain transformed with the Listeria hlyA gene. What parameters did they address in
this study and what were the conclusions drawn from the data?
15. What do Listeria monocytogenes and Shigella flexneri have in common with regard
to their pathogenic strategies?
16. Theriot et al. used a phalloidin-rhodamine conjugate to observe intracellular
Listeria monocytogenes. What does the phalloidin-rhodamine conjugate bind to,
what was the observation made in this study, and what was the conclusion drawn
from the data?
17. Theriot et al. used caged-resorufin bound to G-actin which was micro-injected into
potoroo kidney epithelial cells to investigate actin filament dynamics within the
actin tail formed by Listeria moncytogenes during infection of these cells. How
was caged-resorufin used in their study and what observation was made?
18. In Listeria monocytogenes, actin polymerization mediated by the gene product
ActA has been shown to be polar resulting in unidirectional movement. Design an
experiment to show that actin polymerization is polar because ActA is polar.
19. How did Smith and Portnoy use the Streptococcus pneumoniae protein LytA, and
living S. pneumoniae to demonstrate that polarized localization of ActA was
sufficient for unidirectional movement?
20. What is the primary symptom that gave bubonic plague the name ‘Black Death’?
21. Listeria produces a toxin called listeriolysin O (LLO). LLO is a UNIQUE member
of a family of pore-forming toxins called cholesterol dependent cytolysins (CDC’s).
Another CDC, streptolysin O (SLO), is produced by Streptococcal species. In an
experiment using Yersinia, it was determined that YopB and YopD produce
SMALL pores in the plasma membranes of target-cells in the specific instance
when Yop effectors are deleted. The size of the pores was determined to be small
by showing that a small dye (Lucifer yellow) could enter cells while a larger dye
(Texas red phalloidin) could not. As a control, researchers used SLO to show that
Texas red phalloidin could enter cells. What property of LLO would make this
toxin a pore choice to replace SLO in this experiment.
22. What does the “low calcium response” in Yersinia refer to?
23. The proteins involved in interaction between Y. pseudotuberculosis and Y.
entercolitica with host cells were analyzed using an invasion assay.
a. What is the invasion assay?
b. What types of host and bacterial cells were used and why?
c. What does the result of the assay tell you about the host proteins that interact
with the bacterial cells?
d. From this assay, they found four proteins important in adherence. What would
have been the results if Y. pestis was used in the initial assay?
24. What are three traits that Y. pestis satisfies to classify it as a Category A biological
weapon by the National Institute of Health (NIH)?
25. Two Yersinia adhesins, inv and ail, were identified using a similar assay. Which of
the Molecular Koch’s Postulates were used to identify these adhesins? (no numbers
– fully state the postulate) Are these adhesins important for Y. pestis virulence?
Why?
26. What is the primary purpose of the type III secretion system in Yersinia? What host
cell types are targeted by the Yop/Ysc/Lcr type III secretion system? How would
you identify effectors?
27. What conditions are required for Y. pestis Type III secretion in vitro?
28. Bordetella pertussis is the human adapted pathogen that causes the disease known a
“whooping cough”. B. pertussis is a non-invasive, extracellular pathogen that
colonizes the upper respiratory tract (URT) during pathogenesis.
a. Name 2 innate immune mechanisms that B. pertussis must evade in order to
successfully colonize the URT.
b. Name 2 secreted products expressed by B. pertussis during URT colonization
that knockout the above 2 innate immune mechanisms that you listed.
29. B. pertussis infection is viewed as a two stage pathogenesis process involving first
colonization of the URT and second toxin mediated tissue damage. Name two
virulence factors that are expressed by B. pertussis that are responsible for toxin
mediated tissue damage.
30. BvgAS, the virulence gene regulation locus of pathogenic Bordetella, is a 2
component sensory transduction system. How was BvgAS implicated in phase
variation that occurs with Bordetella pertussis with respect to the virulence
phenotype?
31. In a study designed to determine whether BvgAS of B. pertussis is responsible for
phenotypic modulation of virulence, Miller et al. designed an experimental
approach to find mutants that were insensitive to environmental modulators of
BvgAS.
a. In the genetic construct generated for the above goal by Miller (strain VIR102 of
B. pertussis), why was the pertussis encoding toxin gene fused with the gene
encoding chloramphenicol acetyltransferase that confers resistance to the antibiotic
chloramphenicol?
b. Why was hemolytic activity also assayed along with chloramphenicol
resistance?
c. Why in the genetic construct that they generated (VIR102) did they delete the
wild type BvgAS from the chomosome and then integrate back into the
chromosome a plasmid vector containing wild type BvgAS? How did this allow
them to prove that BvgAS mediates phenotypic modulation?
32. The apparent function of BvgAS in Bordetella pathogens is to determine if
Bordetella is within or outside a mammalian host. The Bvg minus phase in B.
bronchiseptica results in the expression of several products required for survival of
B. bronchiseptica when it is free living in the environment. What is the function of
the Bvg minus phase products expressed by B. pertussis?
33. During B. bronchiseptica infection of rabbits, serum from the infected rabbits have
antibodies against FHA, fimbriae, adenylcyclase, but not flagella. What conclusion
can you draw from this finding with respect to BvgAS?
34. In the “skinny pig” (the ugly hairless guinea pig) aerosol transmission model it was
found that B. bronchiseptica having a wild type BvgAS locus, but not those having
a Bvgc (constitutive Bvg+ phase) locus were transmission competent. Given that
Bvgc is as virulent as wild type, and Bvg- is avirulent, what conclusions were drawn
from this observation?