immuno test 3

How does immunological memory work to prevent and fight disease?

Memory cells reduce time to produce effective response

What is the diversity of T-cell and B-cell receptors?

Allows recognition of a wide variety of pathogens

What is clonal selection of lymphocytes?

Concentrates effector mechanisms to clear infection

What is the timeline of a primary immune response?

Can take up to 14 days to resolve infections

What is the timeline of a secondary immune response?

Can clear an infection in 3 to 4 days

What is the difference between primary and secondary immune responses?

Secondary response is faster and more robust

What is the role of memory cells?

Respond quickly to a second exposure and produce high-affinity immunoglobulins

What is somatic hypermutation?

Process that produces immunoglobulins with increased affinity for antigen

What is isotype switching?

Process that changes the class of immunoglobulin produced by a B cell

What is the action of naïve B cells during a secondary response?

Limited to focus energy on production of high-affinity immunoglobulins

What is the role of memory cells in monitoring for antigens?

Monitor for antigens in tissues other than secondary lymphoid tissues

What are the important products of clonal expansion?

B and T memory cells

What is the lifespan of memory cells?

Long-lived

Do memory cells act to combat the pathogen that promoted their differentiation?

No

What is the approximate time required for a primary adaptive immune response?

14 days

What is required for B-cell activation during a primary immune response?

Interaction with dendritic cells and engagement of T cells

What is limited during the primary immune response?

Immunoglobulin isotypes

What is the reason for the faster rate of the secondary immune response?

Differentiation and action of memory cells

What are memory T cells?

Responsible for rapid adaptive immune response.

How do memory T cells differ from naïve T cells?

Different cell-surface molecules, locations, and APC types.

How are B cells activated?

By CD4 helper T cells in T-cell zone.

What happens to activated B cells in germinal centers?

Undergo isotype switching and somatic hypermutation.

What do activated B cells in germinal centers produce?

Effector plasma cells and memory B cells.

Where do memory B cells localize?

Spleen and other secondary lymphoid tissues.

How does IgG produced by memory B cells inhibit naïve B cells?

Opsonizes pathogen and interacts with inhibitory receptor.

How do naïve lymphocytes obtain survival signals?

Through T-cell receptor or membrane immunoglobulins.

Do memory lymphocytes require survival signals?

No, but cytokines can provide survival signals.

What cytokines can promote survival of CD8+ memory T cells?

IL-7 and IL-15

Where does the majority of lymphocyte activation occur in the primary adaptive immune response?

Draining lymphoid tissues

What is responsible for the secondary adaptive immune response?

Activation of memory T and B cells produced during the primary response

Why is the secondary adaptive immune response faster?

Memory cells reside where they were produced

Why is the secondary adaptive immune response more robust?

Memory lymphocytes do not require costimulation and memory B cells have undergone somatic hypermutation

Which Fc receptor on B cells inhibits naïve B cells from responding during a second encounter?

FcγRIIB1

What is the difference between variolation and vaccination?

Variolation inoculates with smallpox material, while vaccination inoculates with cowpox material

Who was Edward Jenner?

A pioneer in early vaccine development against smallpox

What is the risk associated with variolation?

It caused smallpox in 1% of individuals

What type of vaccines are the Pfizer/BioNTech and Moderna COVID-19 vaccines?

mRNA vaccines

What allowed the rapid development of mRNA COVID-19 vaccines?

The similarity of the coronaviruses that cause SARS and COVID-19, along with 30 years of research in developing mRNA vaccines

What is the purpose of memory cells?

To promote a more robust secondary adaptive immune response upon subsequent exposure to the same pathogen

What is somatic hypermutation?

A process that introduces mutations into the variable regions of immunoglobulin genes in B cells during the process of affinity maturation

What is affinity maturation?

A process by which B cells produce antibodies with increased affinity for the antigen during an immune response

What is the difference between primary and secondary adaptive immune responses?

Primary response occurs upon first exposure, while secondary response occurs upon subsequent exposure and is faster and more robust

What is the role of IL-7 and IL-15 in the immune response?

They can promote survival of CD8+ memory T cells without the need for T-cell receptor engagement

What is the function of Fc receptors?

To bind to the Fc region of antibodies and mediate various effector functions

What is the difference between memory and naïve lymphocytes?

Memory lymphocytes are produced during the primary response and reside where they were produced, while naïve lymphocytes have not encountered the antigen before

What is the purpose of vaccines?

To prevent disease by stimulating the immune system to produce a protective response against a pathogen

What was the study published in the Lancet in 1998 about?

Link between MMR vaccine and autism

Why was the article eventually retracted?

Findings could not be reproduced and conflict of interest

How was vaccination developed against smallpox?

Jenner inoculated an 8-year-old boy with material he had isolated from a milkmaid

What is the goal of vaccination?

Production of memory T and B cells

What are the different types of viral and bacterial vaccines?

Inactivated vaccines

Why do inactivated vaccines usually require booster doses?

First dose does not elicit high level of protection.

What are live attenuated vaccines?

Pathogens that lost ability to cause disease.

Why is a single immunization enough for live attenuated vaccines?

Closely mimics an infection.

What are toxoid vaccines?

Inactivated toxins used to protect against bacterial toxins.

What are subunit vaccines?

Used to protect against pathogen adhesion molecules.

What are conjugate vaccines?

Join weak antigen to strong antigen.

What is the purpose of conjugate vaccines?

To produce a multivalent vaccine with multiple epitopes.

What is the purpose of inactivating toxins in toxoid vaccines?

To prevent disease.

What is the purpose of subunit vaccines?

To raise a primary immune response.

What is the purpose of live attenuated vaccines?

To mimic an infection.

What is the purpose of conjugating a weak antigen with a strong antigen?

To produce a multivalent vaccine.

What is the purpose of neutralizing antibodies?

To bind to adhesion molecules of intracellular pathogen.

What is the purpose of opsonizing antibodies?

To protect against polysaccharide capsule.

What is the purpose of T-cell-independent responses?

To produce opsonizing antibodies.

What is the purpose of pathogen adhesion molecules?

To enter target cells.

What is the purpose of polysaccharide coat?

To prevent host cell phagocytosis.

What is the purpose of neutralizing immunoglobulins?

To block infection by intracellular pathogen.

What is the purpose of formalin or heat treatment?

To inactivate toxins.

What drives the activation of T cells and B cells in conjugate vaccines?

Toxoid and polysaccharide, respectively.

What do activated B cells produce in response to conjugate vaccines?

Opsonizing antibodies to the polysaccharide coat of the bacterial pathogen.

Why do conjugate vaccines commonly require boosters?

To promote full protection against the pathogen.

What are recombinant vector vaccines?

Uses harmless bacteria or attenuated viruses to express a pathogenic antigen.

How are genes encoding pathogenic antigens introduced in recombinant vector vaccines?

Isolated and placed into a plasmid or into a harmless or attenuated virus.

What is the mechanism of DNA vaccines?

Similar to recombinant vector vaccines, but the DNA vaccine is placed directly into the host.

What is the mechanism of messenger RNA vaccines?

Employ an mRNA molecule that encodes an antigen target which is delivered into a target cell.

How is the mRNA modified in messenger RNA vaccines?

Its nucleotides are modified to limit recognition as a PAMP, which limits the potential for an innate immune response.

What are the two mRNA vaccines developed to combat COVID-19?

Pfizer/BioNTech and Moderna.

What is the protective efficacy of two doses of the mRNA COVID-19 vaccine?

90% or higher against the disease.

Can messenger RNA be used for vaccination to a pathogen?

Yes.

When did COVID-19 disease appear?

December of 2019.

Why were vaccine candidates rapidly developed for COVID-19?

To stop the pandemic.

What is the mRNA vaccine made of?

mRNA molecule with modified nucleotides and lipid nanoparticles

How many individuals were vaccinated in the study?

60

What was the purpose of the study?

To test for the generation of a protective immune response

What was the efficiency of mRNA delivery systems in preventing COVID-19 disease?

Efficient

What did the vaccine induce?

Dose-dependent generation of immunoglobulins

What did the immunoglobulins recognize?

Spike protein receptor-binding domain

What was the capability of the immunoglobulins?

Neutralizing virus infection

What did the vaccine promote the production of?

Immunoglobulins that bind to the spike protein and act as neutralizing antibodies

What is the role of an adjuvant in a vaccine?

To induce an inflammatory response and strengthen the immune response.

What must an effective vaccine do?

Promote clonal selection of protective lymphocytes and ensure proper costimulatory signal.

Why is induction of an inflammatory response important in vaccine development?

It activates expression of costimulatory signal B7 on dendritic cells, necessary for activation of naïve T cells.

What are the different vaccine strategies?

Attenuated, toxoid, conjugate, subunit, recombinant vector, mRNA and DNA vaccines.

What are the key concerns in vaccine development?

Safety and effectiveness.

What questions must be addressed in vaccine development regarding safety?

Can the antigen revert to being pathogenic? Can the antigen induce toxicity? Are the adjuvant components safe in humans? Was the vaccine developed in an organism that may induce an allergic response?

What must a vaccine be capable of?

Inducing proper immune response and adequate protection against the pathogen.

What is the best mode of delivery for vaccines?

Depends on the vaccine

How is live attenuated rotavirus vaccine given?

Orally

Who should receive vaccines against emerging infectious diseases?

Those in direct contact with pathogens