MIC 205A Dr. Jan Decker
EXAM 3 KEY
November 5, 2007

Part 1 MULTIPLE CHOICE: Pick the one BEST answer and darken the corresponding letter on the scantron. Each answer is worth 3 points, for a Part 1 total of 90 points.

• An antibiotic is a(n)
• a. chemical made by a macrophage that signals neutrophils to enter the infection site.
• b. chemical made by a microorganism that kills or inhibits the growth of another microorganism.
• c. enzyme that synthesizes peptidoglycan cell walls.
• d. protein made by B cells that binds antigen.

• A part of the human body that IS inhabited by normal flora is the
• a. liver.
• b. nose.
• c. spleen.
• d. stomach.

• Cytotoxic T cells identify virus-infected cells by
• a. complement-coated virus remnants bound to the outside of infected cells.
• b. perforin bound to the outside of infected cells.
• c. virus antigen bound to neutralizing antibody.
• d. virus antigen on infected cell MHC I.

• Penicillin
• a. inhibits the enzyme that crosslinks bacterial peptidoglycan.
• b. is an antibiotic to which bacteria become resistant by making b-lactamase.
• c. rarely causes side effects because it doesn’t block the action of human enzymes.
• d. ALL of the above are true about penicillin.

• Antibiotic resistance occurs when
• a. a person is resistant to dog parvovirus.
• b. antibiotics cause mutations in bacterial genes.
• c. the MIC for a previously effective antibiotic decreases.
• d. the MIC for a previously effective antibiotic increases.

• Lymph nodes
• a. are the site of white blood cell production.
• b. carry white blood cells from the tissues to the blood.
• c. filter pathogens from the blood.
• d. filter pathogens from the lymphatics.

• The portal of entry for respiratory anthrax is the
• a. blood.
• b. digestive tract.
• c. lungs.
• d. skin.

• Phagocytes identify pathogens using receptors for
• a. activated complement coating the pathogen.
• b. common pathogen antigens like LPS.
• c. the Fc part of antibodies opsonizing the pathogen.
• d. ALL of the above are true about macrophage receptors for antigen.

• ALL of the following contribute to the re-emergence of cholera EXCEPT
• a. altered Vibrio cholerae antigens.
• b. ocean warming.
• c. reduced use of insecticides.
• d. reduction in water treatment because of fear of cancer.

• Honey is the ___________ that spreads infant botulism.
• a. etiology
• b. pathogenic agent
• c. vector
• d. vehicle

• B cells that bind influenza virus are activated to become
• a. cytotoxic B cells that kill influenza viruses in infected host cells.
• b. helper B cells that activate cytotoxic T cells.
• c. neutralizing B cells that engulf and kill the virus.
• d. plasma cells that secrete neutralizing antibodies to the virus.

• A symptom of infectious disease is [Credit given for all answers, but review the technical meaning of a symptom - as opposed to a sign- of disease.]
• a. a skin rash.
• b. fever.
• c. itching.
• d. All of the above are disease symptoms.

• [WHITE] Receiving anti-rattlesnake venom following a rattlesnake bite confers
• a. artificial active immunity.
• b. artificial passive immunity.
• c. natural active immunity.
• d. natural passive immunity.

• [PINK] Receiving gamma globulin to protect against Hepatitis A confers
• a. artificial active immunity.
• b. artificial passive immunity.
• c. natural active immunity.
• d. natural passive immunity.

• [BLUE] Recovering from a chickenpox infection confers
• a. artificial active immunity.
• b. artificial passive immunity.
• c. natural active immunity.
• d. natural passive immunity.

• The most numerous white blood cells that are attracted to an infection site to engulf and destroy bacterial pathogens are
• a. B cells.
• b. eosinophils.
• c. macrophages.
• d. neutrophils.

• Recombinant vaccines like the hepatitis B vaccine
• a. are usually made when giving the whole pathogen is too risky.
• b. consist of pathogen antigen proteins produced by (for example) yeast cells given pathogen DNA.
• c. usually require several  exposures for good protection.
• d.All of the above are true.

• Complement is a group of blood proteins that is activated to
• a. coat pathogens so they are more readily phagocytosed.
• b. form pores in some pathogen membranes to lyse them.
• c. stimulate inflammation.
• d. ALL of the above are functions of complement.

• Natural killer cells function in innate immunity like  ____________ function in adaptive immunity.
• a. cytotoxic T cells
• b. dendritic cells
• c. macrophages
• d. neutrophils

• [WHITE] The antibody that crosses the placenta to protect the child from infection is
• a. IgA.
• b. IgD.
• c. IgE.
• d. IgG.
• e. IgM.

• [PINK] The antibody that is most effective against helminth (worm) parasites is
• a. IgA.
• b. IgD.
• c. IgE.
• d. IgG.
• e. IgM.

• [BLUE] The antibody that blocks pathogen adherance to mucous membranes is
• a. IgA.
• b. IgD.
• c. IgE.
• d. IgG.
• e. IgM.

• Unlike the above picture, fomites are actually  _____________ that transmit pathogens from one person to another.
• a. biting insects
• b. droplets
• c. foods
• d. inert objects like door knobs

• MRSA is
• a. a new antibiotic developed to treat multi-drug-resistant Mycobacteria.
• b. increasingly seen as normal flora on the skin and in the nose.
• c. only found in hospitals where high levels of antibiotics are used.
• d. untreatable by any antibiotics.

• [WHITE] The tetanus “shot” is an example of a(n) _____________ vaccine.
• a. attenuated
• b. recombinant
• c. toxoid
• d. whole cell

• [PINK] The Salk polio “shot” is an example of a(n) _____________ vaccine.
• a. attenuated
• b. killed virus
• c. recombinant
• d. toxoid

• [BLUE] The MMR “shot” is an example of a(n) _____________ vaccine.
• a. attenuated
• b. recombinant
• c. toxoid
• d. whole cell

• During an infection, bacteria release enzymes into body tissues in order to
• a. attach to host cells.
• b. induce an immune response.
• c. spread to deeper tissues.
• d. survive inside phagocytes.

• [WHITE, PINK] Th2 cells
• a. can be transferred from one person to another for passive cellular immunity.
• b. help B cells make antibodies and memory B cells.
• c. help macrophages kill pathogens in their phagosomes.
• d. help virus-infected cells kill viruses in their cytosol.

• [BLUE] Th1 cells
• a. can be transferred from one person to another for passive cellular immunity.
• b. help B cells make antibodies and memory B cells.
• c. help macrophages kill pathogens in their phagosomes.
• d. help virus-infected cells kill viruses in their cytosol.

• A systemic infection is
• a. easily controlled by the immune response.
• b. latent.
• c. present in many areas of the body simultaneously.
• d. without symptoms.

• Humoral immunity can be passively transferred from one person to another by giving
• a. B cells.
• b. cytokines.
• c. serum.
• d. T cells.

• The antigen receptors on BOTH B and T cells
• a. are antibodies.
• b. are synthesized from genes that are uniquely rearranged for each cell.
• c. bind both peptide antigen and MHC.
• d. can be secreted from the cell.

• Selective toxicity is the ability of an antimicrobial drug to
• a. be bactericidal.
• b. kill many different kinds of microbes.
• c. kill microbes while not harming host cells.
• d. prevent superinfection.

• A cellular immune response would be required to eliminate
• a. a bacterial toxin.
• b. a helminth infection.
• c. an encapsulated bacterium.
• d. a virus infection.

• Human behaviors that contribute to antimicrobial resistance (make it worse) include
• a. eating organic foods that are raised without antibiotics.
• b. finishing all of the antibiotic prescribed even after symptoms have disappeared.
• c. not taking antibiotics for a virus infection.
• d. taking only broad spectrum antibiotics.

• Microscopic copepods living in the ocean are the __________ for cholera.
• a. etiology
• b. index host
• c. portal of entry
• d. reservoir

Part 2 ESSAY: Answer TWO of the following questions in the space provided.

• Describe TWO bacterial virulence factors and how each damages the body.
  • Attachment via pili to avoid removal by peristalsis, coughing, etc.
  • Avoiding removal by the immune system: capsules or biofilms to avoid phagocytosis, blocking killing by macrophages, changing antigens to avoid adaptive immunity, blocking antigen presentation on MHC I to avoid cytotoxic T cells, coating themselves in host antigens
  • Secreting enzymes to break down host connective tissue so the pathogen can spread
  • Secreting exotoxins that kill host cells
  • Endotoxin (part of outer membrane of Gram negative bacteria) that overstimulate host macrophages, causing septic shock

• Explain how the presence of an antibiotic increases the number of antibiotic-resistant bacteria.
  • Antibiotic-resistant bacteria result from spontaneous mutations and horizontal transfer of resistance genes
  • In the presence of antibiotic, resistant bacteria have a selective advantage and grow better than sensitive bacteria, becoming a larger percentage of the population.

 

• Describe the differences between a primary (first) and secondary (repeat) antibody response to a pathogen. [You may draw a diagram if you like.]

• The initial response has a longer lag period since it takes longer to activate naive B and T cells than it does memory cells.
• IgM is made first in the primary response; IgG is made later. In the secondary response, IgG is made faster since the memory B cells have already switched to IgG. The IgM made in a memory response is due to new B cells that have been made since the initial response.
• The secondary (memory = anamnestic) response is larger and lasts longer than the primary response.