Exam 1 MC

Question 1

which of the following is/are characteristics of an inapparent infection?

Answer 1

infection does not lead to over disease

overt disease not caused and microbe in parasitic relationship with host

Question 2

Which of the following are possible outcomes of infection with hepatitis B virus?

Answer 2

• acute liver disease
• long term carrier of HBV(chronic Carriage)
• the persistent infection can remain asymptomatic(inapparent)
• chronic liver disease.

(ALL THE ABOVE)

Question 3

Which of the following is/are characteristics of organisms that establish endogenous infections in humans?

Answer 3

• caused by microbes that come from inside the body
• commensal or mutualistic relationship
• opportunistic pathogens

Question 4

Which of the following are factors that might predispose an affect person to Chromobacterium violaceum infection?

Answer 4

• those with weak immune systems

- large inoculum size

Question 5

The Gram-negative bacterium, Vibrio Cholera generally is considered to have high infective dose in humans. What does it mean to have a high infective dose?

Answer 5

Large number of organisms is required to cause disease

Question 6

Which of the following factors contribute to pathogenesis (disease causation) for all types of pathogens (B,V,F,P)?

Answer 6

• Presence or absence of specific virulence factors
• Intrinsic to host: status of host immune system
• Stochastic Factors: Inoculum size and normal host barriers of entry

Question 7

Which of the following cell types is/are involved only in antigen-specific immune responses?

Answer 7

CTLs

Question 8

Which of the following are among the microbial killing mechanisms used by phagocytes?

Answer 8

Acidification
toxic oxygen-derived products
toxic nitrogen oxides
antimicrobial peptides
Enzymes
competitors
-digestion of bacterial cell walls with lysozyme
-generation of toxic oxygen and nitrogen molecules

Question 9

Which of the following strategies may be used by intracellular pathogen to avoid being killed following phagocytosis into macrophages?

Answer 9

• Inhibition of the fusion of the phagosome with lysosome…blocking phagolysosome formation
• secretion of phospholipases to degrade the phagosome membrane before the fusion
• resisting the effects of the toxic products and enzymes present within the phagolysosome

Question 10

Which of the following important molecules of the innate immune system are involved in attracting leukocytes to sites of infection?

Answer 10

Complement small fragments and chemokines

Question 11

People with liver damage have reduced capacity to control infection by a number of bacteria and fungi. Which of the following immune system component would you expect to be affected directly by liver damage?

Answer 11

acute phase proteins and complement

Question 12

Which of the following are effector function of complement large fragments?

Answer 12

• Major role is to opsonize bacteria (make the susceptible for phagocytosis)
• Get cross-linked into target cell membrane (limits diffusion, helps prevent “collateral Damage”)

Question 13

Which of the following cell types can activate macrophages?

Answer 13

TH1 T-cells

Question 14

After encountering a pathogen in peripheral tissues, plasmacytoid dendritic cells do which of the following?

Answer 14

secrete a/B-interferon

Question 15

Which of the following are characteristics of a pathogen associated molecular pattern?

Answer 15

-“signatures” of broad classes of pathogen..more generic

PAMPs are limited to the molecules/structures they ca detect. Antigens in all types of variation so aren’t as limited as PAMPs.

Question 16

What two types of signaling molecules are secreted by macrophages when they detect bacteria?

Answer 16

cytokines and chemokines

Question 17

Which of the following types of leukocytes may undergo extravasations at a site of local inflammation?

Answer 17

Neutrophils and monocytes

Question 18

What is the purpose of clonal deletion lymphocyte development?

Answer 18

-eliminate lymphocytes that have rearranged antigen receptor for self antigen, which ensures tolerance to self antigens

Question 19

What is the purpose of clonal expansion during an adaptive immune response?

Answer 19

to increase the number of individual lymphocytes that have a specific rearranged antigen receptor (one that will recognize the pathogen antigen of question)

Question 20

If a person were exposed to rabies virus via a bite wound, what class(es) of antibody directed against the virus would be most likely to prevent systematic spread of infection?

Answer 20

IgG

Question 21

Vibrio Cholera is an extracellular pathogen that causes disease without invading tissues. What class(es) of antibody directed against V. cholera 01, or its exotoxin, would be able to protect against disease caused by this bacterium?

Answer 21

IgA

Question 22

Clostridium tetani is an extracellular pathogen that can cause systemic disease, even though the bacteria do not disseminate. What class(es) of antibody directed against C. tetani, or its exotoxin, would be most important for preventing tetanus?

Answer 22

IgG and IgA

Question 23

Which of the following cell types can activate B cells?

Answer 23

Antigens
TH2 T-cells
some TH1 T-cells too!

Question 24

Which of the following cell types can present antigens to CD8+ T-cells?

Answer 24

Dendritic cells

Question 25

Mycobacterium tuberculosis is an intracellular pathogen that infects macrophages. Which of the following humoral and/or cellular effectors of the immune system would be most important for combating infection by M. tuberculosis?

Answer 25

Macrophages and TH1 T-cells