Jackson: Vaccination Flashcards
Active Immunization
What does administration of vaccine elicit?
Natural infection elicits:
Administration of a vaccine that elicits a protective immune response
Natural infection that elicits an active response
Passive Immunization
Transfer of maternal Abs to infant via placenta or colostrums
Therapeutic administration of Abs to protect host
Post-Exposure Immunization
Type of immunization
Use:
Passive + active immunization
Used for diseases that have potentially acute onset and fatal outcomes
Post-Exposure Immunization
For Diphtheria
For Rabies
Toxoid + antitoxin for diphtheria exposure
Immunoglobulin + vaccine for rabies exposure
Induction of secondary response
What is rapid amamnestic response important for?
Rapid amamnestic response important for prevention of diseases with short incubation periods
Induction of secondary response
Example:
Multiple injections of tetanus toxoid given to children (DTaP) to boost production of protective levels of circulating Abs (boosters to raise titers)
Role of innate response
Acquired immunity can function both independent of and in concert with innate defenses
Acquired immunity can function independent of innate defenses (Ab to toxoid directly neutralizes toxin)
Acquired immunity can function in concert with innate defenses (Ab can opsonize infectious particles/interact with complement to induce lysis of infecting agent)
Age of Immunization
What protects fetus and newborn?
Why is vaccine delayed until 1 year of age?
Maternal Ig protects fetus and newborn (newborn can mount responses to toxoids and polio vaccine)
Circulating maternal Ab can interfere with immunization against measles (vaccine delayed until 1 year of age)
Herd Immunity results from:
Results in:
Results from the vaccination of a significant portion of the population
Results in a net decrease in the spread of disease, preventing epidemics
Vaccines must induce the right type of immune response
TB:
TB: requires a vaccine that elicits a cell-mediated response (not an overly effective vaccine because of this)
Vaccines must induce the right type of immune response
Streptococcal pneumonia:
Streptococcal pneumonia: requires a vaccine that elicits an anti-capsular Ab (but body does not respond well to polysaccharide antigen)
Vaccines must induce the right type of immune response
Poliovirus:
Poliovirus: having high levels of serum Ab are unlikely to protect from poliovirus mucosal infection (need IgA response in GI tract)
Must induce memory to protect against future infections
Natural boosting:
Paradox of vaccination:
Natural boosting: Occurs during periodic outbreaks in the community
Paradox of vaccination: the less disease there is (ie. as a result of vaccination), the more there is a need for vaccination
Must be stable and relatively inexpensive
Cold chain:
Cold chain: refers to the need to keep vaccines refrigerated for stability (some countries may lack the resources to do so)
Live Attenuated
In general:
In general: induce a stronger and longer lasting immunity than non-living vaccines
Live Attenuated
Preparation
How is the pathogen virulence reduced?
Used for:
Example:
Passage in culture: pathogen is repeatedly passed in culture until its virulence is reduced
Used for the development of many viral vaccines
Example: BCG (TB vaccine) is the best example- 10 year passage in culture
Live Attenuated
Preparation
Cold adaptation:
Cold adaptation: forces virus to be less viable at body temperature
Live Attenuated
Risks
Insuffcient attenuation:
Insufficient attenuation/reversion to wild type: mutations induced in the vaccine strain during attenuation are entirely at random and not predictable
However, it is possible to use genetic engineering to construct vaccine strains with defined mutations
Live Attenuated
Risks
What can be induced by living viruses?
Risks to what populations?
Persistent infection induced by living virus
Risks to immunocompromised or a fetus/newborn
Killed Organisms
In general:
Use:
Example:
In general: safer but have reduced immunogenicity and require multiple doses
Use: if attenuation of the pathogen has not been achieved or if the risk of reversion to the wild type is too high
Example: poliovirus vaccine exists in both inactivated (Salk) and attenuated (Sabin) forms; has returned to the use of the inactivated form to avoid the risks associated with reversion
Subcellular
Use
Examples
Use: when protective immunity may be induced against some component of the pathogen
Examples: capsular polysaccharides and inactivated toxins (toxoids)
Conjugate Vaccines:
Example:
Conjugate Vaccines: may be used due to the poor immunogenicity of some subcellular fractions; made of a toxoid conjugated to the capsular material of a bacterial pathogen
Example: Haemophilus influenza b (Hib) capsular polysaccharide conjugated to tetanus or diphtheria toxoid or Neisseria outer membrane protein
Recombinant Vector Candidates: (4)
What could be used for antigens of pathogens like Vibrio cholera?
What elicits T cell response; could be used for persistent intracellular pathogens like Toxplasma and Listeria?
Adenovirus
Vaccinia virus
Salmonella typhi (enteric pathogen that could be used for antigens of pathogens like Vibrio cholera)
BCG (elicits T cell response; could be used for persistent intracellular pathogens like Toxplasma and Listeria)
DNA Vaccines:
Designed to protect against disease by injecting naked DNA that expresses Ag to produce an immunological response; subject not injected with actual Ag, but with DNA encoding the Ag
Attenuated vaccines
Advantages
Best for what age?
Localized to where?
What do T cells process?
Best prevent childhood diseases that induce effective long-term immunity following recovery from infection
Localize to the natural site of infection and replicate there
T cells process the peptide Ags and associate them with MHC class I molecules using the native route
Attenuated vaccines
Disadvantages
Risk of:
What would be more effective for diseases with high antigenic diversity?
Risk of reversion
Are not useful against diseases caused by agents with high antigenic diversity (ie. influenza)
- Would be more effective to use a subcellular vaccine containing Ags required for viral attachment or entry
Live Vaccine
Preparation
Administration
Dosage
Preparation: Attenuation
Administration: May be natural (ie. oral)
Dosage: Single dose possible