Biol 430Question Bank Vaccines

1. A child who had not yet received a tetanus immunization received a deep wound to his heel by stepping on the lid of an old metal can. His mother rushed him to the health clinic where the child’s wound was cleaned and sutured (it required 5 stitches). Adding “insult to the injury”, the child was also required to get a shot of the tetanus antitoxin.

  1. Why was the child given the tetanus antitoxin instead of the tetanus toxoid?
  1. Having received the antitoxin, will the child be protected against a similar injury in the future?

2. Suppose that you were developing a new vaccine from polysaccharide components of a bacterial capsule. Initially, you start with the purified form of a single type of polysaccharide. Explain why each of the following vaccine modification may improve the immune response?

  1. covalently coupling the polysaccharide to a protein carrier.
  1. adding aluminum hydroxide.
  1. using more than one type of polysaccharide in combination.
  1. using the vaccine for older children and adults, but not infants
  1. using a recombinant virus expressing the polysaccharide.

A colleague suggests that since the bacteria you are working with is an intracellular pathogen that you should instead be developing live, attenuated form of the vaccine.

F. What reasons could you give him for preferring the molecular component approach?

G. For what reasons may your colleague be right?

3. The oral Sabin (live attenuated) polio vaccine is no longer recommended in the US, but is used in other countries where the incidence of polio is still a serious problem. Why.

4. All other differences between the vaccines being equal:

  1. for a disease with a short incubation period would a live attenuated vaccine or a dead inactivated vaccine be preferred?
  1. What about for a disease with a long incubation period?
  1. What type of vaccine (other than the two mentioned above) would be called for if the pathogen will release a serious toxin shortly after the infection occurs
  1. Explain you answers.

5. Some parents worry that combinational vaccines such as MMR or DTaP might “overwhelm” the immune system and leave a child more susceptible to other diseases. Based upon your knowledge of the mechanisms of the immune system, explain why this fear is unfounded.

6. For each of the following treatments, indicate if it is an example of passive (‘P’) immunization, active (‘A’) immunization, therapeutic (‘T’)immunization, or neither (‘N’):

___ tetanus antitoxin___ tumor antigens

___ maternal IgA___ tetanus (DTaP) vaccine

___ polio vaccine___ IVIG

___ antiviral drugs

7. For each one of the following characteristics, indicate which type of vaccine that characteristic best describes:

____ potential risk of causing infection

____ most likely to activate cell mediated armA. DNA vaccine

____ causes cells to produce a specific B. Inactivated pathogen

antigen of a pathogenC. Attenuated pathogen

____ carries many eptitopes, activates aD. Toxoid

humoral response better than cell-mediatedE. Molecular component

____ most likely to require refrigeration.

____ carries few epitopes, but is very safe

____ active against a toxic product of a pathogen

8. Identify these vaccines:

Protects against

Vaccinewhich disease(s)Type of vaccine

MMR______

DTaP______

HiB______

PCV______

HBsAG______

FluMist______

OVP______

9. While blood type incompatibility is rarely a problem during pregnancy, Rh incompatibility can be.

  1. Rh incompatibility will occur only if the mother is Rh- and the child is Rh+? Why?
  1. Why does problem posed by Rh incompatibility manifest itself on subsequent but not the first pregnancy involving an Rh+ child?
  1. Rhogam, the treatment for Rh incompatibility disease, needs to be administered shortly after delivery in order to be effective. Why?
  1. Is Rhogam given to the mother or the child? ______
  2. Considering the mechanism of action, need rhogam be administered after each pregnancy involving an Rh+ child, or only the first?

10. The origin of new strains of influenza involves both genetic drift and genetic shift.

  1. Which one of these mechanism yields the largest genetic variations?
  1. Which mechanism is principally responsible for annual variations.
  1. Explain how genetic shift might yield a H2N1 influenza strain from H3N1 and H2N2?
  1. Explain why a new pandemic form of influenza, will likely arise from antigenic shift followed by drift.
  1. Many people fear that the world’s health services would be unable to stem a pandemic if a deadly form of influenza reemerges. Describe the challenges to developing and distributing a vaccine for a new pandemic form of influenza.

11. There are several compounding factors hindering the development of vaccines for protozoal diseases, such as malaria. Explain each of these factors why it poses a challenge to vaccine development:

  1. geographic distribution in poor nations
  1. complex life cycles of the pathogens
  1. transmission through a vector (e.g., mosquito)
  1. abiltity of the pathogens to undergo antigenic shift
  1. slow onset and chronic nature of disease symptoms

Can you suggest a why transmission through a vector may pose a unique opportunity for an alternative strategy to control spread of a disease?

12. Evidence suggests both serum IgG and mucosal IgA are important to protection against lethal influenza H5N1, although the relative importance of these immunoglobins and how they are best generated is yet unresolved. Valdy et al compared the efficacy of different combinations of intramuscular (IM) and intranasal (IN) immunizations using a mouse system.

Two groups of 3 female BALB/c mice each were immunized twice at a 3-week interval with HA fromthe Jiangsu strain, by IM/IM, IN/IN, IN/IM, or IM/IN routes ofimmunizations. At 7 days after the final immunization, pools of 3mice each were sacrificed and single-cell suspensions wereprepared from cervical lymph nodes and analyzed by ELISPOTassay.

The ELISpot assay is used to count the number of cells that secrete a particular type of antigenby distributing the cell suspension over membranes coated with antibodies against the antigen of interest. In this case the membranes were coated with either anti-IgG or anti-IgA antibodies, which would bind to IgG or IgA secreted from the plasma cells. After an incubation period, the cells were washed off, and the membrane is treated with a secondary antibody / substrate staining system. The position of each antigen secreting cell appears as a spot, as shown in the image to the right. An animation of the Elispot procedure is also available from the Biol 430 download web page.

In the graph below, the results are presented as the number of antibody-secreting cells (ASC) per millionmononuclear cells (MNC).

  1. Explain how the spots in the sample ELISpot image are created.
  1. Which treatment yielded the highest number of IgA secreting cells in the cervical lymph nodes?
  1. Which treatment yielded the fewest IgG and IgA secreting cells?
  1. When IN and IM immunization are used in combination, does the order of the immunizations matter?
  1. Do these results support your expectations for the nature of a humoral response to different routes of exposure? Explain.

Vajdy M, Baudner B, Del Giudice G, O’Hagan D. 2007. A vaccination strategy to enhance mucosal and systemic antibody and T cell responses against influenza. Clinical Immunology123: 166–175.

Biol 430Question Bank Vaccination

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