2005 Sample C106 Midterm Examination:
1.
How does mucus production function as a defense mechanism in the upper
respiratory tract of humans?
2.
How do members of the normal bacterial flora serve as a defense mechanism
against potential bacterial pathogens?
3.
Name 2 ways in which the activated complement system defensively works during
an innate immune response?
4.
Name 2 types of professional phagocytes and describe in general terms how they
engulf and destroy microorganisms?
5.
Name 3 different types of bacterial PAMPs that stimulate the acute phase response
of innate immunity?
6.
Adaptive immunity that involves CD4+ lymphocytes and a Th1-like response
results in what type of immune effector molecules or cells? What type of bacterial
pathogenic strategy are these effector molecules or cells most effective against?
7.
Name 2 ways in which specific antibody functions defensively against a bacterial
pathogen?
8.
In the Vibrio cholerae study of Peterson and Mekalanos, why was the transposon
tnphoA chosen to search for virulence genes of V. cholerae. What property about a
gene or gene product does the tnphoA transposon indicate following transposition
and how is this accomplished?
9.
How does the plasmid pFPV25 function to identify promoters? Following
transformation of recombinant pFPV25, how are transformants initially selected
and then identified for functioning promoters?
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10. In the pIVET system developed by Mahan and Mekalanos, what was the purpose of
including the promoterless purA gene on the plasmid, i.e. how was it used to find
the induced in vivo genes? What is the second reporter gene of this system and
what is its function? Why was this system rather than transposon mutagenesis used
to identify virulence expressed genes?
11. How does the DNA microarray technique allow transcription identification of the
entire genome of an organism? What is the term for the transcription profile of the
entire genome?
12. What are common structural features of the botulism and tetanus toxins (note: not
the functions of these toxins)?
13. How does the tetanus toxin cause a spastic paralysis whereas the botulism toxin
causes a flaccid paralysis?
14. List three main classes of virulence factors produced by Staphylococcus aureus.
Give at least one example of each class and suggest a mechanism for each.
15. List at least 3 main bacterial targets for the most commonly used classes of
antibiotics?
16. What is the amino acid sequence recognized by sortase? What does sortase attach
substrate proteins to? What major class of virulence factor is processed by sortase?
Give one example.
17. Staphylococcus aureus secretes an exotoxin called alpha toxin. This protein is
produced as a water-soluble monomer. Describe two changes to this structure that
occur upon interaction with mammalian cells.
18. What aspect of the autoinducing peptide (AIP) did Richard Novick’s research group
take advantage of to identify the AIP receptor? How can this be used to devise a
therapeutic to treat Staph infections?
19. What are the three main routes of infection by Bacillus anthracis? What is the
infectious stage of the Bacillus anthracis life cycle?
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20. What are the two main virulence factors produced by Bacillus anthracis and what
are they encoded on?
21. List the three components of anthrax toxin. What are their functions and relative
contributions to virulence? What two other pathogens covered in class produce
toxins that are structurally or functionally similar to individual components of
anthrax toxin?
22. Describe how Smith and Keppie discovered anthrax toxin in 1954. Why did it take
50 years to discover this toxin?
23. What is the “point of no return” with respect to anthrax? What does this tell us
about the treatment window when using antibiotics? How would you circumvent
this?
24. How would you evaluate Streptococcus mutans induced dental caries with Koch’s
Postulate?
25. Why board-spectrum antibiotics work effectively against many other microbial
infections, but have limited efficiency against oral microbial infection?
26. Name 3 cell wall components of Mycobacterium tuberculosis that differentiate its
cell wall from typical gram positive cell walls?
27. What type of adaptive immune response that develops during the course of
tuberculosis is most effective against the causative agent, Mycobacterium
tuberculosis?
28. What is the name of the specialized host immune generated structure that is
responsible for the containment and dormancy of M. tuberculosis during
tuberculosis infection?
29. Vaccination against tuberculosis using the attenuated M. bovis strain known as the
“Bacille of Calmette-Guerin; BCG” is used in many places in the world but is not
used in the United States. Give on reason why the BCG vaccine is not used in the
U.S.?
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30. The integrating cosmid shuttle vector known as pYUB178 was used by Collins et
al., PNAS, 1995, to complement virulence of an attenuated strain of Mycobacterium
bovis (ATCC strain) using DNA from a virulent strain of M. bovis (WAg200
strain).
a. What was the purpose of the lambda cos site on the pYUB178 cosmid?
b. Why was it desired to clone into pYUB178 large fragments of DNA from the
WAg200 strain (these fragments were approximately 30 to 50kbp in size)?
c. Following transformation of M. bovis ATCC strain with recombinant pYUB178,
containing cloned WAg200 DNA, 4000 transformed integrates were selected by
antibiotic resistance. 12 of these 4000 integrates were randomly chosen and their
chromosomal DNA was isolated and digested with the restriction endonuclease
Pst1. The restricted DNA from each of these 12 clones was electrophoretically
separated and analyzed by Southern hybridization using a probe specific to the
cloning region of the pYUB178 plasmid. In general terms, what was were findings
of this analysis and what was the significance?
d. Following guinea pig infection using the above 4000 integrates (a total of 107
organisms were used/guinea pig), organisms were isolated from infected guinea pig
spleen lesions and a total of 14 of these isolates were randomly chosen and
analyzed as described above in question 25c. Again in general terms, what were the
findings of this analysis and what was the significance?
e. Collins et al. showed that a common 2.3kb Mlu1 restriction fragment was
common to all integrates that were recovered from infected spleen lesions. How
was it confirmed that this restriction fragment contained the gene or genes
responsible for virulence complementation?
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