Immunology Overview and Discussion of the Types of Immunizing Agents Flashcards
(31 cards)
Two Lines of Defense
- Innate/Passive Defenses
- Physical Barriers
- Secretions
- PH extremes
- Adaptive
- Non-specific Innate response
- Adaptive Response
immune System - Definitions
immunity
active vs passive
immunization
adaptive immune system
passive immune system
▪ 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
specificity, tolerance, memory
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
Cell Mediated vs Humoral Immunity
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
Immune Response (Humoral)
primary and secondary
- 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
Does the Presence of Antibodies Indicate
Immunity?
Maybe?
- 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
Immune
Response to a
Vaccine
- 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
Types of Immunizing Agents
- Active
- Vaccines
- Inactivated
- Live attenuated
- Toxoids
- Passive
- Immunoglobulins
- Antitoxins
What is in a Vaccine?
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
Adjuvants
- 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
Preservatives
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
Other Components
- 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
Types of Vaccines
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)
Attenuated
Vaccines
- 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
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)
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
Inactivated Vaccines
pros cons
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
Inactivated Vaccines
Typically occur within 48 hours:
*fever
*irritability
* drowsiness
*local pain and swelling
* vomiting
Subunit Vaccines
- 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
Subunit - Polysaccharide
▪ 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
Subunit – Conjugated Polysaccharide
*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
Subunit - Protein
- 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)
Toxoids
▪ 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
Nucleic Acid Vaccines
- 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
mRNA Vaccines
pros cons
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)
