Week 8 - Immunity and Immunization

Question 1

Define immunology.

Answer 1

Study of the components and function of the immune system

Question 2

What makes up the immune system? What does it protect against?

Answer 2

Molecules, cells, tissues and organs which provide non-specific and specific protection against microorganisms, microbial toxins, tumor cells

Crucial to human survival

Question 3

What are the 5 roles of the immune system?

Answer 3

Defense against infections

Defense against tumors

Clearance of dead cells and tissue repair

Can injure cells and induce pathologic inflammation

Recognizes and responds to tissue grafts and newly introduced proteins

Question 4

What are the 2 implications of defense against infections?

Answer 4

Deficient immunity results in increased susceptibility to infections; exemplified by AIDS

Vaccination boosts immune defenses and protects against infections

Question 5

What is the implication for defense against tumors?

Answer 5

Potential for immunotherapy of cancer

Question 6

What is the implication of clearance of dead cells and tissue repair?

Answer 6

Deficient immunity can lead to secondary infections after injury, and excessive immune responses can lead to fibrosis and organ dysfunction

Question 7

What is the implication of the immune system can injure cells and induce pathologic inflammation?

Answer 7

Immune responses are the cause of allergic, autoimmune, and other inflammatory diseases

Question 8

What is the implication of the immune system recognizing and responding to to tissue grafts and newly introduced proteins?

Answer 8

Immune responses are barriers to transplantations and gene therapy

Question 9

What are the 2 kinds of immune response? What are the 2 kinds of acquisition of immunity?

Answer 9

Immune response:
Innate (non-specific): first line of defense in response to all pathogens
Adaptive/acquired (specific): secretes antibodies to specifically target a pathogen

Acquisition of immunity: natural and artificial

Question 10

What is the innate immune system? What are the 2 lines of innate defenses?

Answer 10

Innate: structural defenses; responds to nonspecific foreign substances

First line: external surface epithelium & membranes

Second line: inflammatory processes (antimicrobial proteins, phagocytes, fever, inflammation, and NK cells)

Question 11

What are the 5 steps of phagocytosis?

Answer 11

1. Microbe adheres to phagocyte
2. Phagocyte forms pseudopods that eventually engulf the particle
3. Phagocytic vesicle is fused with a lysosome and creates a phagolysosome
4. Microbe infused vesicle is killed and digested by lysosomal enzymes within the phagolysosome, leaving a residual body
5. Indigestible and residual material is removed by exocytosis

Question 12

Defne active immunity.

Answer 12

Long-lasting protection (memory) and multiple effector mechanisms activated

Question 13

Define passive immunity and give an example.

Answer 13

Rapid protection and short duration

Example: injection of globulins, antibody passage through mother’s milk to infant, or passage of antibodies to baby from placenta

Question 14

Define adaptive immune system.

Answer 14

Responds to specific foreign substances

Adaptive defenses: B-cells (humoral immunity) and T-cells (cellular immunity)

T-cells: T-helper cells and T-cytotoxic cells; attack pathogen directly and do not secrete antibodies
Antigen presenting cells: macrophages, dendritic cells, B lymphocytes, etc.

Question 15

What are the 7 features of adaptive immune responses?

Answer 15

Specificity

Diversity

Memory

Clonal expansion

Specialization

Contraction and homeostasis

Nonreactivity to self

Question 16

What are the functional significances of each of the 6 features of the adaptive immune responses?

Specificity
Diversity
Memory
Clonal expansion
Specialization
Contraction and homeostasis
Nonreactivity to self

Answer 16

Specificity: ensures that distinct antigens elicit specific responses

Diversity: enables immune system to respond to a large variety of antigens

Memory: leads to enhanced responses to repeated exposures to the same antigens

Clonal expansion: increases number of antigen-specific lymphocytes to keep pace with microbes

Specialization: generates responses that are optimal for defense against different types of microbes

Contraction and homeostasis: allows immune system to respond to newly encountered antigens

Nonreactivity to self: prevents injury to the host during responses to foreign antigens

Question 17

What two features best distinguish adaptive and innate immunity?

Answer 17

Specificity and memory

Question 18

What are the 4 details (2 for observational and 2 for implications) about Edward Jenner?

Answer 18

Jenner observes that dairy maids who had been infected with cowpox – a disease with similar but milder symptoms than smallpox – appear immune to smallpox infection

Experiment: Inoculation with cowpox material in 8-year-old boy and challenge 6 weeks later with smallpox

Jenner did not have knowledge of the causative agent of smallpox – his work was strictly empirical, yet highly effective in controlling smallpox

Serious issues with regard to informed consent

Question 19

What are the 7 prerequisites for an effective vaccine?

Answer 19

1. A natural model of effective immunity and response should be life-long
2. Safety: vaccine must pose little risk
3. Minimal immune evasion: if the microbe changes epitopes, a vaccine is likely to become ineffective
4. Practical to manufacture: is mass production feasible?
5. Durability: is the vaccine’s protection “durable” (long lasting)?
6. Practice use: is administration practical? Example: preservation, refrigeration need, etc.
7. Cost: is the vaccine affordable? Is there a “market”?

Question 20

How do vaccines work when compared to the natural model of infection?

Answer 20

Natural model of infection:
1. Disease causing microorganism infects host
2. Host has an immune response
3. Recovery, death, or disability and immune memory

Vaccination:
1. Vaccine antigen is introduced
2. Antigen causes immune response without infection
3. Host recovers and gains immune memory

Question 21

What are the 7 types of vaccines?

Answer 21

Inactivated vaccines

Live, attenuated vaccines

Subunit vaccines

Toxoid vaccines

Conjugate vaccines

mRNA Vaccines

DNA vaccines

Question 22

What are 3 details about inactivated vaccines? What are the concerns? Give an example.

Answer 22

The disease-causing microbe is killed with chemicals, heat, or radiation

Such vaccines are more stable and safer than live vaccines; the dead microbes can’t mutate back to their disease-causing state

Inactivated vaccines usually don’t require refrigeration, and they can be easily stored and transported

Concerns: incomplete inactivation, less than optimal immune response

Example: injected Polio vaccine

Question 23

Explain the Cutter incident.

Answer 23

1940s: inactivated polio vaccine had circumstances that did not lead to a complete inactivation of the polio virus

Vaccine administered to children all over the U.S.

Results: 40,000 cases of polio, 200 children with varying degrees of paralysis, and 10 deaths

Future implication: creating of FDA oversight into manufacturing and safety of vaccines

Question 24

What are 3 details about live attenuated vaccines? What are the concerns? Give an example.

Answer 24

The microbe that has been weakened in the lab so it can’t cause disease

Because a live, attenuated vaccine is the closest thing to a natural infection, these vaccines are good “teachers” of the immune system

They elicit strong cellular and antibody responses and often confer lifelong immunity with only one or two doses

Concerns: reversion, contraindications for some patients, refrigeration

Example: polio vaccine (oral), measles, mumps, chicken pox

Question 25

What are 3 details about subunit vaccines? What are the concerns? Give an example.

Answer 25

Include only the antigens that best stimulate the immune system; in some cases, these vaccines use epitopes—the very specific parts of the antigen that
antibodies or T cells recognize and bind to

Less likely to produce adverse effects as many components are eliminated

Produced by either: 1) grow the microbe in the laboratory and then use chemicals to break it apart, or 2) manufacture
the antigen molecules from the microbe using recombinant DNA technology (vaccines produced this way are called
“recombinant subunit vaccines”)

Concerns: Have you selected the most immunogenic epitopes? Are the “epitopes” constant, or do they change?

Example: Hepatitis B vaccine

Question 26

What are 2 details about toxoid vaccines? What are the concerns? Give an example.

Answer 26

For bacteria that secrete toxins, or harmful chemicals, a toxoid vaccine may be appropriate; used when a bacterial toxin is the main cause of illness

The toxin is formalin-inactivated, administration can induce an antibody response which later protects the individual from the effects of the toxin

Concerns: it must be possible to effectively clear the bacterial infection

Examples: Diphtheria, tetanus

Question 27

What are 2 details about conugate vaccines? Give an example.

Answer 27

If a bacterium possesses an outer coating of sugar molecules called polysaccharides, these can disguise bacterial antigens so that the immature immune systems of infants and younger children can’t recognize or respond to them

Conjugate vaccines link antigens from a microbe to the polysaccharides

Examples: Hepatitis B, influenza (injection), Haemophilus influenza type b (Hib), Pertussis (part of DTaP combined immunization), Pneumococcal, Meningococcal

Question 28

What are 4 details about the COVID-19 vaccine?

Answer 28

Coronaviruses have crown-like spikes on the surface (spike proteins) which are ideal targets for vaccines

mRNA is genetic material that tells your body how to make proteins

COVID-19 vaccine is made of mRNA wrapped in a coating that makes delivery easy and keeps the body from damaging it

mRNA in vaccine teaches body how to make copies of the spike protein and the body will recognize the real virus and know how to fight it off

Question 29

What do vaccines contain? Give examples of preservatives and adjuvants in specific vaccines

Answer 29

In addition to the bulk antigen that goes into a vaccine, vaccines are formulated with other fluids (such as water or saline), additives or preservatives, and sometimes adjuvants

Preservatives: phenol (typhoid, pneumococcal polysaccharide), benzethonium chloride (anthrax), 2-phenoxyethanol (inactivated polio), and thimerosal (multi-dose influenza)

Adjuvants help the body create a stronger immune response

Adjuvants: aluminum salt (Hepatitis A and B, diphtheria, tetanus, acellular Pretusis combinations, Haemophilus influenzae type B, pneumococcal conjugate, and Japanese encephalitis, HPV), AS04 (aluminum salt and monophospholipid A) (HPV), and MF59 (oil in water emulsion; one vaccine) (H1N1 influenza)

Question 30

What are 4 details about DNA vaccines? Give an example.

Answer 30

These vaccines utilize the microbe’s genetic material; in particular, DNA vaccines use the genes that code for those all-important antigens

When these genes are introduced into the body some cells will take up that DNA and produce the antigens and display them on their surfaces

In other words, the body’s own cells become vaccine-making factories, creating the antigens necessary to stimulate the immune system

Such vaccines remain experimental

Examples: flu, HIV, etc. (developmental stages only)

Question 31

What two factors contribute to vaccine ability to control/eliminate a disease?

Answer 31

The effectiveness and the durability of the effect of the vaccine and level of vaccination coverage achieved in a given population

Question 32

Define vaccine efficacy.

Answer 32

Measures the decrease in incidence of a disease in the vaccinated population compared to the incidence of the disease in the unvaccinated

Question 33

Define herd immunity.

Answer 33

Form of immunity that occurs when the vaccination of a significant portion of a population (or herd) provides a
measure of protection for individuals who have not developed immunity

Question 34

Why do we not have vaccines for serious protozoal diseases like malaria or African sleeping sickness?

Answer 34

Complex life cycles and undergo “antigenic shift” (different antigens at different life cycles and it’s hard to find one that’s present in all life cycles)

Plasmodium causes malaria (mosquito is vector)

Trypanosoma causes African sleeping sickness (tsetse fly is vector)

Question 35

What are 7 issues with vaccination?

Answer 35

Vaccine Adjuvants

Vaccines During Pregnancy

Vaccine Recalls

Febrile Seizures after Childhood Vaccinations

Guillain-Barré Syndrome (GBS)

Autism and Vaccines-Thimerosal (Preservative used in Some Flu Vaccines)

Multiple Vaccines and the Immune System

Question 36

What are the 3 hypotheses for the relationship between vaccines and autism?

Answer 36

The combination measles-mumps-rubella vaccine causes autism by damaging the intestinal lining, which allows the entrance of encephalopathic proteins

Thimerosal, an ethylmercury-containing preservative in some vaccines, is toxic to the central nervous system

The simultaneous administration of multiple vaccines overwhelms or weakens the immune system

Question 37

Define autism.

Answer 37

Group of complex neurodevelopment disorders characterized by repetitive and characteristic patterns of behavior and difficulties with social communication and interaction

Question 38

Describe the Wakefield study and its limitations.

Answer 38

Described 8 children whose first symptoms of autism occurred within 1 month of receiving MMR vaccine

Premise was that measles virus caused invasion of “encephalopathic peptides” to enter through the GI tract and enter the brain

Study limitations: no control subjects, no blinding of assessments, MMR viruses had never been associated with loss of intestinal barrier function…and there was no evidence that “encephalopathic peptides” had ever travelled from intestine to brain to cause neurologic
damage

Question 39

What are 3 details about the epidemiological investigation into Wakefield’s claims?

Answer 39

Multiple studies failed to corroborate Wakefield’s claims

2004: as UK vaccination rates drop from above 95% to 80%, ten of Wakefield’s coauthors issue retractions

In 2010, after years of stating they probably shouldn’t have published it, Lancet editors retract the paper, as fraud is charged in handling of every one of the 8 cases reported

Question 40

What are examples of active and passives forms of naturally and artificially acquired immunity?

Answer 40

Naturally acquired:
Active: infection; contact with pathogen
Passive: antibodies pass from mother to fetus via placenta or to infant through milk

Artificially acquired:
Active: vaccine; dead or attenuated pathogens
Passive: injection of immune serum (gamma globulin)

Question 41

What are the steps for how the adaptive immune system fights pathogens?

Answer 41

1. Pathogen is encountered, macrophage encounters them, and presents them to B-cells
2. B-cells differentiate to form plasma and memory B-cells
3. Plasma cells secrete antibodies that bind to pathogens and cause clearance
4. Memory B-cells remain dormant until they come into contact with the pathogen for a second time, then they quickly divide into plasma cells

Question 42

What is the CDC’s recommended vaccination schedule for children and adults?

Answer 42

Children:
Hepatitis B: 1st dose at birth, 2nd dose 1-2 months, and 3rd dose at 6-18 months
Rotavirus, Tdap, Hib, pneumococcal, and inactivated polio: 1st dose at 1-2 months, 2nd dose at 4 months
Influenza: 2 doses at first, then 1 dose yearly
COVID-19: recommended for 6 months and above

Adults:
Influenza: every year
MMR: 1-2 doses depending on indication
Varicella: 2 doses
HPV: 2-3 doses depending on age at initial vaccination
Hep B: 2-4 doses depending on vaccine or condition