Question 1

For each of the descriptions of immune mechanisms in questions ,select the immune mechanism (A-D)that correctly matches it.
Adaptive immunity mechanism for eradicating established viral infection

A)Type I interferons (IFN-a,IFN-b)
B)CD8+ cytolytic T lymphocyte
C)Antibody
D)Natural killer cell

CD8+ cytolytic T lymphocyte

Accepted Answer

Once viruses have infected cells,they produce cytoplasmic proteins that are processed and presented by the class I MHC pathway.CD8+ cytotoxic T lymphocytes recognize viral peptide-class I MHC complexes on the surface of infected cells and kill these cells.The killing mechanism leads to apoptosis,which ensures degradation of viral DNA as well as host cell DNA.

Question 2

Match the description of a vaccine in questions with the correct type of vaccine (A-G).
Composed of antigens purified from microbes or inactivated toxins,such as the tetanus toxoid vaccine

A)Live attenuated or killed bacteria
B)Live attenuated oral virus
C)Synthetic viral subunit vaccines
D)Conjugate vaccines
E)Recombinant viral vectors
F)DNA vaccines
G)Purified subunit vaccines

Accepted Answer

Synthetic subunit viral vaccines are composed of viral proteins synthesized from recombinant genes.The hepatitis B virus vaccine,now in widespread use,was the first synthetic viral subunit vaccine to be developed and contains the recombinant hepatitis B surface antigen (HBsAg).

Question 3

Match the description of a vaccine in questions with the correct type of vaccine (A-G).
Composed of a recombinant nonpathogenic virus carrying genes of a pathogenic virus,such as HIV

A)Live attenuated or killed bacteria
B)Live attenuated oral virus
C)Synthetic viral subunit vaccines
D)Conjugate vaccines
E)Recombinant viral vectors
F)DNA vaccines
G)Purified subunit vaccines

Recombinant viral vectors

Accepted Answer

Genes encoding immunodominant epitopes of a pathogenic virus can be cloned into the genome of nonpathogenic viruses,and the resulting recombinant virus can be used as a vaccine against the pathogenic virus.This is one of the approaches under development for HIV (human immunodeficiency virus)vectors.
Multiple Choice

Question 4

A common strategy by which microbes survive their host's immune responses involves changing the structures of the molecules they produce so that they are no longer recognized by the host's immune system.This strategy,called antigenic variation,is most likely to allow evasion of which type of immune recognition?

A)Toll-like receptor-dependent recognition of microbes by cells of the innate immune system
B)Mannose receptor-dependent recognition of microbes by cells of the innate immune system
C)Antibody recognition of microbial cell surface molecules
D)Natural killer cell inhibitory receptor recognition of class I major histocompatibility complex (MHC)molecules on infected cells
E)T cell receptor recognition of microbial cell wall lipid antigens

Accepted Answer

Antigenic variation allows microbes to evade adaptive immune recognition,usually by antibodies,but also by T cells.Antigenic variation usually involves mutations or recombination events in microbial genes encoding cell surface proteins or encoding enzymes involved in synthesis of cell surface sugars.The result changes microbial surface antigens.This is an effective strategy,because many of the microbial antigenic structures that the adaptive immune system recognizes,are not essential for survival or virulence of the microbe.In contrast,most structures recognized by receptors of the innate immune system (e.g. ,Toll-like receptor and scavenger receptor ligands)are essential for microbial survival and,as such,cannot undergo antigenic variation.Although some viruses may block class I major histocompatibility complex (MHC)expression by infected cells,this renders the cells more susceptible to natural killer cell-mediated killing and is not antigenic variation by the virus.Only a small subset of T cells recognizes lipid antigens,usually in association with CD1 molecules.There is no evidence for antigenic variation of the lipid antigens recognized by these T cells.

Question 5

For each of the descriptions of immune mechanisms in questions ,select the immune mechanism (A-D)that correctly matches it.
Adaptive immunity mechanism for eradicating established viral infection

A)Type I interferons (IFN-a,IFN-b)
B)CD8+ cytolytic T lymphocyte
C)Antibody
D)Natural killer cell

Accepted Answer

One of the key innate immunity responses that can prevent viral infection is the production of type I interferons (IFNs),which are secreted by various cell types in response to double-stranded RNA interacting with endosomal Toll-like receptors,ssRNA binding to cytoplasmic Rig-like receptors,and dsDNA binding to cytosolic DNA sensors.Type I IFNs induce an antiviral state in cells,which makes them resistant to host viral replication.

Question 6

Match the description of a vaccine in questions with the correct type of vaccine (A-G).
Induction of a T cell-dependent antibody response to polysaccharides,such as Haemophilus influenzae B and pneumococcal capsular polysaccharides

A)Live attenuated or killed bacteria
B)Live attenuated oral virus
C)Synthetic viral subunit vaccines
D)Conjugate vaccines
E)Recombinant viral vectors
F)DNA vaccines
G)Purified subunit vaccines

Accepted Answer

Conjugate vaccines are composed of bacterial capsular polysaccharides covalently coupled to proteins.This hapten-carrier arrangement promotes T cell-dependent responses to the polysaccharides,which is required for protective IgG memory responses,with high affinity IgG and long lived memory.Polysaccharides alone do not activate T cells and therefore do not induce robust isotype switching,affinty maturation,or memory cell generation.

Question 7

Match the description of a vaccine in questions with the correct type of vaccine (A-G).
Induction of a T cell-dependent antibody response to polysaccharides,such as Haemophilus influenzae B and pneumococcal capsular polysaccharides

A)Live attenuated or killed bacteria
B)Live attenuated oral virus
C)Synthetic viral subunit vaccines
D)Conjugate vaccines
E)Recombinant viral vectors
F)DNA vaccines
G)Purified subunit vaccines

Accepted Answer

The most commonly used purified subunit vaccines are the diphtheria and tetanus toxoid vaccines,which induce protective antibody responses against toxins produced by the bacteria.

Question 8

Protection against extracellular bacterial infections such as with staphylococci,and extracellular fungi,,such as with Candida,is in part mediated by which of the rolling types of T cell responses?&#10;A)Cytotoxic T lymphocytes&#10;B)Th 1 cells&#10;C)Th2 cells&#10;D)Th17 cells&#10;E)Regulatory T cells&#10;

Accepted Answer

Extracellular microbes may be readily killed after ingestion by neutrophils.Th17 responses enhance neutrophilic responses to infection by secreting IL-17,which increases bone marrow production of neutrophils,and induces TNF production that in turn increases expression of chemokine and adhesion molecules that increase meutrophilic recruitment to sites of infection.

Question 9

For each of the descriptions of immune mechanisms in questions ,select the immune mechanism (A-D)that correctly matches it.
Adaptive immunity mechanism for eradicating established viral infection

A)Type I interferons (IFN-a,IFN-b)
B)CD8+ cytolytic T lymphocyte
C)Antibody
D)Natural killer cell

Accepted Answer

Antibodies can neutralize viruses before they infect cells.Immunity imparted by many antiviral vaccines is due to antibodies.

Question 10

Match the description of a vaccine in questions with the correct type of vaccine (A-G).
Induction of a T cell-dependent antibody response to polysaccharides,such as Haemophilus influenzae B and pneumococcal capsular polysaccharides

A)Live attenuated or killed bacteria
B)Live attenuated oral virus
C)Synthetic viral subunit vaccines
D)Conjugate vaccines
E)Recombinant viral vectors
F)DNA vaccines
G)Purified subunit vaccines

Accepted Answer

Live attenuated viral vaccines infect recipient cells,and viral proteins are processed and presented to T cells.This method of vaccination induces good T cell-dependent antibody responses.Attenuation makes risk of serious disease from the vaccine very low.Live attenuated oral poliovirus vaccines,which induced good IgA responses in the gastrointestinal tract,are no longer used routinely in the United States because of low but definable risk of vaccine-associated cases of paralytic polio.

Question 11

Some viruses evade CTL-mediated immunity by expressing molecules that have which of the following actions?&#10;A)Inhibition of the TAP peptide transporter&#10;B)Inhibition of proteolysis of the invariant chain&#10;C)Stimulation of proteasome activity&#10;D)Activation of immune regulatory factors (IRFs)&#10;E)Inhibition of IL-5 production&#10;

Accepted Answer

The answer of Some viruses evade CTL-mediated immunity by expressing...

Question 12

For each of the descriptions of immune mechanisms in questions ,select the immune mechanism (A-D)that correctly matches it.
Adaptive immunity mechanism for eradicating established viral infection

A)Type I interferons (IFN-a,IFN-b)
B)CD8+ cytolytic T lymphocyte
C)Antibody
D)Natural killer cell

Accepted Answer

The answer of For each of the descriptions of immune...

Deck 4: Microbial-Immunity