Question 1

Match the description of a vaccine in questions ,with the correct type of vaccine (A-G).
Composed of viral proteins synthesized from recombinant viral genes

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

Synthetic viral 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 2

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, and trials of canarypox virus containing SIV (simian immunodeficiency virus) genes have been used in primates with some success.
Multiple Choice

Question 3

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

Conjugate 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
Polysaccharides alone do not activate T cells and therefore do not induce isotype switching or memory cell generation.

Question 4

Matching&#10;For each of the descriptions of immune mechanisms in questions , select the immune mechanism (A-D) that correctly matches it.&#10;Innate immunity mechanism for eradicating established viral infection&#10;A) &#10;B) &#10;C) &#10;D)

Accepted Answer

Natural killer (NK) cells are innate immunity effector cells that can kill infected cells by mechanisms similar to cytotoxic T lymphocytes (CTLs)
However, they are activated by different receptors than are CTLs, and they are inhibited by receptors that bind class I MHC on other cells
Viruses have the ability to evade detection by CTLs by inhibiting class I MHC expression on their host cell surfaces
When this occurs, NK cells may provide a backup defense mechanism, since they are activated by host cells that lack normal class I MHC expression.

Question 5

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 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

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 7

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 8

Matching&#10;For each of the descriptions of immune mechanisms in questions , select the immune mechanism (A-D) that correctly matches it.&#10;Innate immunity mechanism for preventing viral infection&#10;A) &#10;B) &#10;C) &#10;D)

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 Toll-like receptors
Type I IFNs induce an antiviral state in cells, which makes them resistant to host viral replication.

Question 9

Matching&#10;For each of the descriptions of immune mechanisms in questions , select the immune mechanism (A-D) that correctly matches it.&#10;Adaptive immunity mechanism for preventing a viral infection&#10;A) &#10;B) &#10;C) &#10;D)

Accepted Answer

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

Question 10

Matching&#10;For each of the descriptions of immune mechanisms in questions , select the immune mechanism (A-D) that correctly matches it.&#10;Adaptive immunity mechanism for eradicating established viral infection&#10;A) &#10;B) &#10;C) &#10;D)

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.

Deck 18: Immunity to Microbes