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446 m > Immunology Overview and Discussion of the Types of Immunizing Agents > Flashcards

Immunology Overview and Discussion of the Types of Immunizing Agents Flashcards

1
Q

Two Lines of Defense

A
    1. Innate/Passive Defenses
  • Physical Barriers
  • Secretions
  • PH extremes
    1. Adaptive
  • Non-specific Innate response
  • Adaptive Response
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2
Q

immune System - Definitions

immunity
active vs passive
immunization
adaptive immune system
passive immune system

A

▪ Immunity: state of being protected from or resistant to a particular disease due to the production
of antibodies
▪ Immunity involves the Ag-Ab response
▪ Active vs. passive
* Active – antigenic stimulation of immune system
* Passive – acquisition of preformed Abs

Antigen upregulation, stimulate your own immune system
Maternal passed to fetus, blood transfusion, plasma transfusion or specificaly given immunoglobulins

▪ Immunization: process of inducing or providing immunity by administering an agent
▪ Adaptive Immune System: Foreign agent is recognized in a specific manner and the immune
system acquires memory of it
▪ Passive Immune System: The part of the immune system that protects the body without
changing or adapting to the exposure

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3
Q

specificity, tolerance, memory

A

Characteristics:
Specificity - to an Antigen
Tolerance - Differentiate Self from
Non-Self
Memory – Subsequent exposure
results in a rapid and
strong immune response
Divided into two parts:
1. Cell-Mediated Immunity
2. Humoral (antibody) Immunity

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4
Q

Cell Mediated vs Humoral Immunity

A

cell mediated: Tkiller cells
Humoral: antibodies produced to protect from exposure
Plasma cells are factory cells that make antibodies then die off

Memory B cells last forever, just float around

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5
Q

Immune Response (Humoral)
primary and secondary

A
  • Primary immune
    response develops in the
    weeks following first
    exposure to an antigen
  • Mainly IgM antibody
  • Secondary immune
    response is faster and
    more powerful
  • Predominantly IgG
    antibody
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6
Q

Does the Presence of Antibodies Indicate
Immunity?
Maybe?

A
  • There are many factors that contribute to immunity of which antibodies are just one factor.
  • Antibodies tell us that the body has had or tried to respond to an antigen exposure previously
  • There are factors that affect the usefulness of antibody levels
  • Time since last exposure
  • Type of exposure
  • Individual response
  • Vaccine type
  • Variants and mutability of the antigen
  • There are some that we have established guidelines based on historical data
  • Hepatitis B (within 1 year of the last dose)
  • Rabies
  • MMR and Varicella
  • COVID

Antibodies doesn’t mean that you’re protected
Humoral need a certain target amount dpeneding on the virus

Need to test titres
Antibodies creep down over years as plasma cells die off
If re-exposed for hep b, it will go up based on 2nd exposure

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7
Q

Immune
Response to a
Vaccine

A
  • Vaccine is taken up by antigenpresenting cells
  • Activates both T and B cells to
    give memory cells
  • Generates Th and Tc cells to
    several epitopes
  • Antigen persists to continue to
    recruit B memory cells and
    produce high-affinity antibody
  • Takes ~ 2 weeks to establish
    adequate immunity following
    exposure to the antigen.
    Note: Polysaccharide vaccines do not activate T cells and are the exception to the above

Apc is non-specific, like WBC, neutrophil
Break down large antigen or present a smaller one
Takes 2 wks to establish first effect, protection lvl ramps up over time

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8
Q

Types of Immunizing Agents

A
  • Active
  • Vaccines
  • Inactivated
  • Live attenuated
  • Toxoids
  • Passive
  • Immunoglobulins
  • Antitoxins
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9
Q

What is in a Vaccine?

A

Vaccine Components - Vaccines may or may not contain the following:
* Antigen (All vaccines will contain some kind of antigen to elicit an immune response)
* Adjuvants
* Preservatives*
* Stabilizers
* Buffers
* Antibiotics
*Since 2001 , Routine children’s vaccines do not contain
Thimerosal

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10
Q

Adjuvants

A
  • substance added to a vaccine to enhance the immune
    system’s response
    *induce inflammatory factors to injection site – helps
    immune response
  • may cause injection site reactions
  • examples:
  • Aluminum salts (aluminum hydroxide, aluminum phosphate)
  • AS04
  • MF59

Keeps antigen in local area w inflamm so it doesn’t spread
Local pain, tenderness caused by adjuvants

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11
Q

Preservatives

A

used in vaccines to prevent bacterial or
fungal contamination
required for vaccines in multi-dose vial
- 5 doses in it or very short half-life like covid
Examples:
* Phenol: extremely small amount
* Phenoxyethanol
* Thimerosal

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12
Q

Other Components

A
  • Additives support growth and purification
  • Antibiotics - neomycin, streptomycin, polymyxin B
  • Egg proteins
  • Formaldehyde
  • Lactose, gelatin, human and bovine serum albumin etc
  • Most of additives removed during manufacturing – trace or residual amounts
    may remain (may be concern if anaphylactic reaction)

Grown on egg cell cultures, flu shots but not a worry anymore
Breakdown stuff from vaccine, to kill things off but small amount

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13
Q

Types of Vaccines

A

Live-attenuated
* Measles, mumps, rubella
* Varicella (chickenpox)
* Rotavirus
* Yellow fever
Most concerns
Should remember

Inactivated/Killed
* Polio (IPV)
* Hepatitis A
* Rabies
Subunit/conjugate
* Hepatitis B
* Influenza (infection)
* Haemophilis influenza type b (Hib)
* Human papillomavirus (HPV)
* Pertussis
* Pneumococcal
* Meningococcal
* Zoster (shingles)
Toxoid (Inactivated Toxin)
* Diphtheria
* Tetanus
mRNA
* COVID-19 (Pfizer, Moderna)

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14
Q

Attenuated
Vaccines

A
  • attenuated strains which replicate in host
  • attenuation means the virus or bacterium has been
    weakened to reduce virulence so it cannot cause
    disease in healthy people
  • act like natural infection
    *live vaccines are the closest to actual infection and
    therefore elicit good, strong, long-lasting immune
    responses
    Doesnt replicate or insert as fast
    Usuall good for life like an actual infection
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15
Q

Live Attenuated Vaccines
pros cons

  • Side effects often mimic the disease.
  • E.g. MMR – fever and rash can occur 7-12 days
    following immunization
  • Sensitive to exposure to heat and light.
  • Shake/swirl gently until pellet completely dissolved
    (no bubbles)
A

Advantages
* Single dose often sufficient to induce long-lasting immunity
* Strong immune response evoked
* Local and systemic immunity produced

Disadvantages
* Potential to revert to virulence
* Caution/contraindicated in immunosuppressed patients
* Interference by passive
antibody, potentially other
live vaccines
* Poor stability
* Potential for contamination
with adventitious viruses

Live polio vaccine

Blood transfusion, can’t get it
Or baby under < 1
Carrying antibodies in system, vaccine won’t be effective
Can give 2 live vaccines at the same day or need to wait at least 1 month later

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16
Q

Inactivated Vaccines
pros cons

A

Advantages
*Stable
*Constituents clearly defined
*Unable to cause the
infection
Disadvantages
*Need several doses
*Local reactions common
*Adjuvant needed
* keeps vaccine at injection
site
* activates antigen
presenting cells
*Shorter lasting immunity

17
Q

Inactivated Vaccines

A

Typically occur within 48 hours:
*fever
*irritability
* drowsiness
*local pain and swelling
* vomiting

18
Q

Subunit Vaccines

A
  • Instead of the entire microbe, contain only antigens that best stimulate the
    immune system
  • Typically, adverse reactions are lower as the vaccine contains only essential
    antigens
19
Q

Subunit - Polysaccharide

A

▪ Protect against certain encapsulated bacteria (e.g., pneumococcal)
▪ Capsule contains either polysaccharides that surround the cell and can be removed from the cell
▪ T-cell independent immunogens
* Proteins need to be present to illicit proteolytic digestion

20
Q

Subunit – Conjugated Polysaccharide

A

*attaching (linking) the polysaccharide antigen to a protein carrier – creates an effective immunogen
Generally use diptheria toxoid as the protein componet to bind to T helper cells, polysac binds to B cells
* Illicits T and B cell immune response
*Examples: Hib, meningococcal, pneumococcal (Prevnar)

Conjugation is the process of attaching (linking) the polysaccharide
antigen to a protein carrier (e.g. diphtheria) that the infant’s
immune system already recognizes in order to provoke an immune
response

21
Q

Subunit - Protein

A
  • Purified, inactivated proteins from the outer coating of viruses or bacteria
  • Aluminum salt added as adjuvant to enhance immune response
  • Examples: acellular pertussis, some influenza
  • Some subunit vaccines synthesized using recombinant technology (e.g.,
    hepatitis B vaccine)
22
Q

Toxoids

A

▪ Antigens derived from toxins
▪ Detoxified without destroying their effectiveness as an antigen
▪ Generally combined with aluminum salts to enhance immunogenicity
▪ Immune response generates antitoxins that neutralize the virulent toxins associated with the disease
▪ Examples: diphtheria, tetanus

  • Giving protection to a toxin produced by a bacteria, fungus etc.
  • Tetanus, diphtheria
  • Require multiple doses for immunity
  • Likely need boosters as protection wanes over time
  • Side effects similar to subunit vaccines
23
Q

Nucleic Acid Vaccines

A
  • These types of vaccines include both mRNA and DNA-type vaccines
  • Both present significant technical hurdles due to stability issues outside of the cell
  • Both also face hurdles of acceptance from the public who misunderstand how they work

mRNA Vaccines
* Gene-based vaccine
* Carry the genetic instructions for the host’s cells to make the antigen which more closely
mimics a natural infection
* Essentially getting our cells to produce the subunit or protein of interest
* for coronaviruses – the antigen of interest is the surface spike protein
* researchers knew to focus on coronavirus spike protein based on research from SARS and MERS
* Prior to COVID-19, potential mRNA vaccines against SARS, MERS, rabies, influenza, Zika and a few other viruses have been studied in small early-phase trials

24
Q

mRNA Vaccines
pros cons

A

Advantages
* Lower cost and ease of
production (not grown in
eggs or cells)
* No risk of preexisting
immunity which can limit
effectiveness (compared
to viral vector vaccines)
* May allow in future for
one vaccine to target
multiple diseases
Disadvantages
* Stabilize/protect mRNA
* Long-term efficacy and
safety (e.g., very rare or
long-term side effects)

25
Q

Combination Vaccines

pros cons

A

Refers to a vaccine that includes antigens for the prevention of more
than one vaccine-preventable disease (e.g., measles-mumps-rubella)

Advantages:
* Reduces the number of
injections
* Improves adherence to
immunization schedules
* Facilitates the uptake of new
vaccine
* Reduces costs

Disadvantages:
* If have a reaction to a dose you do
not know what vaccine may have
caused the reaction.
* May actually lower uptake or
acceptance by some groups

26
Q

Factors in Vaccine Response
Factors in Immune Response

A

intrinsic host factors
vaccine factors

▪ Vaccine Factors:
* Nature of antigen – live attenuated versus inactivated/subunit
* Total dose (e.g., number of doses given, interval between doses)
* Example: hepatitis B non-responders – may mount vaccine response when given additional doses
* Presence of vaccine adjuvants
* Route (e.g., hepatitis B has consistent response administered IM in deltoid but not gluteal)
▪ Host factors
* circulating Abs (e.g. maternal Abs), immunodeficiency, age, underlying disease, genetic background
Variable response in gluteal

Passed to baby in umbilical cord
Kids<9 have less developed immune system than older kids, same w older adults
- Zoster better given at 50, less effective as older
Inflamm disease less responsive, inflamm cytokines are overloading your system

27
Q

Immune Response

A

Immune response to
replicating vaccines
Immune response to nonreplicating vaccines

28
Q

Vaccine Failure

A

Primary failure
* an individual fails to make an adequate immune response to the initial vaccination (e.g. in
about 10% of measles and mumps vaccine recipients)
* Secondary failure
* an individual makes an adequate immune response initially but then immunity wanes
over time (a feature of most inactivated vaccines, hence the need for boosters in somecases)

1st dose, IgM never amounted enough to do anything
We give them another dose, 99% effective, still the primary curve of the vaccine
NOT A BOOSTER IN THIS CASE

2ndary - wanes over time, need booster

29
Q

Timing of Vaccine Reactions

A
  • Inactivated vaccines: generally, within 48hrs following vaccination
  • Live vaccines: occur according to time taken for virus to replicate
  • MMR vaccine -Mild fever, rash, and swelling of glands in cheeks or neck can occur about
    7-12 days after getting the vaccine
30
Q

Interval Between Vaccine Doses

A
  • If vaccines are given too close together it can result in less than optimal
    response
  • Longer intervals between doses of schedule is usually fine
  • In general, inactivated vaccines can be administered at the same time or any
    time before or after other inactivated vaccines or live vaccines
  • Live vaccines must be administered at the same visit or separated by a period
    of at least 4 weeks
31
Q

Vaccine Drug Scheduling

A
  • Most vaccines are schedule 1 (National Drug Schedules), except:
  • Covid Vaccines (Schedule 2)
  • Influenza (Schedule 2)
  • Pneumococcal polysaccharide vaccine (Schedule 2)
  • Shingrix (Schedule 2)
  • Vaccines that are part of a routine immunization program in most/all provinces/territories;
    cholera vaccine (oral, inactivated) when used for prophylaxis against traveler’s diarrhea;
    vaccines requiring special enhanced public access due to disease outbreaks (see
    https://napra.ca/national-drug-schedules)
  • Alberta exception to the National Drug Schedules:
  • see ACP website for drug schedules (https://abpharmacy.ca/drug-schedules)
  • Many routine childhood vaccines schedule 1

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