Vaccines Flashcards
What is passive immunization?
administration of preformed antibody in order to give temporary protection against infection
- no memory immunity established
What is an example of passive immunization that occurs in all humans?
Antibodies of maternal origin provide the newborn with a measure of protective systemic and local immunity
- mainly IgG and IgA (via breastfeeding)
what 2 sources can be used for pooled gamma globulin ?
immunized horses or humans
How many approved monoclonal antibody drugs are there on the market? names?
only one
- called Synagis®, palivizumab
What can result from repeated administration of gamma globulin from foreign species? what is made?
systemic anaphylaxis due to a Type 1 hypersensitivity
- IgE is made against the foreign protein
an IgG or IgM response to foreign antigen can result in…
serum sickness (type III) due to immune complex deposition
What can human gamma globulin trigger? what types of hypersensitivities?
anti-allotypic antibody response resulting in Type I or Type III
hypersensitivity
What is an anti-allotypic response?
An antibody response against the Fc portion of foreign antibody
What is the point of active immunization
generate protective immunity and immunologic memory so that a subsequent exposure to the pathogen will stimulate a vigorous immune response
through what two ways can you achieve active immunization?
- natural infection
2. vaccination
What is heard immunity? what does it rely on? who is it designed to protect?
Indirect protection from infectious disease due to a large percent of the population becoming immune to infection (through immunization mainly)
Relies on at least 90% of the population being immunized
Protects people who cannot be immunized
-Newborns, pregnant or breast feeding women, immune compromised people
What are the 2 things that must be induced by a vaccine in order to effectively stimulate the adaptive immune response?
- B cell/humoral response
- make antibodies specific for the pathogen to neutralize and opsonize etc. - T cell/cell mediated response
- cytotoxic t cells kill infected cells and prevent spread of infection
What is an antigen?
any substance capable, under appropriate conditions, of inducing a specific immune response and reacting with the products of that response
If the incubation period of a disease is short, it is important to..?
maintain high levels of antibody by repeated immunizations
What 4 things should antigens used for vaccines be?
safe, stable, readily available, cheap
Only which type of cells need to be activated in order to generate a protective DTH response against TB?
Th1 cells
Poliovirus vaccines need to contain..
both B and T cells epitopes to generate humoral immunity in the form of secretory IgA
In order to induce protective immunity against measels virus…
the pathogen must be allowed to undergo limited replication in host cells for viral antigen to be presented via class I MHC to precursor CTL
what is the concept of live related vaccines?
- Immunize with a closely related but much less pathogenic
organism - Count on immunologic cross-reaction in response
What are 2 examples of live related vaccines?
cowpox for smallpox
L. major for L. donovani
What are 3 positives for live related vaccines?
very strong protection persistent antigen source, lots of antigens available
what are 2 negatives for live related vaccines?
risk of serious infection, lack of available non-pathogenic relatives to common human pathogens
What is the concept of live attenuated vaccines?
Weaken pathogenicity/growth ability of a pathogen
Allows for activation of immune response but not disease
How can you achieve attenuation?
chemical treatment, radiation, or molecular manipulation
what are 3 examples of live attenuated vaccines?
MMRV, Flumist (inhalant flu vaccine) and oral polio vaccine (Sabin)
What 4 positives for live attenuated vaccines?
- Persistence
- full spectrum of antigens - both humoral and cell mediated immunity activated
- limited boosting required
What 2 negatives for live attenuated vaccines
- risk of disease if the pathogen reverts back
- require careful storage and handling
what is the concept of inactivated vaccines?
- pathogens that have been heat or chemically killed
- unable to replicate but maintain antigenic constitution
What is the split virus method?
pathogen particles are inactivated then disrupted with detergent or ether to minimize irritation
What are 2 examples of inactivated vaccines?
IPV (Salk polio vaccine)
Seasonal flu
What are 2 positives for inactivated vaccines
Very safe
wide spectrum of antigens
what are 6 potential negatives for inactivated vaccines?
- no persistance
- limited cell mediated immunity generated
- often require an adjuvant
- boosting often required
- antigens may be damaged during pathogen killing
- very rare: incomplete activation of pathogen can lead to disease
What is the concept of Sub unit vaccines?
Isolate a protein or make a recombinant protein from a pathogen
Deliver it with an adjuvant
- often alum
What are 2 examples of subunit vaccines?
Tdap/DTaP and seasonal flu
What are 3 positives for sub unit vaccines?
- very safe
- easily stored/transported
- can be used for organisms that produce fatal toxins
What are 5 negatives for subunit vaccines?
- weak immunogens
- require adjuvant
- need boosting
- no spectrum of antigens
- no persistance
What is the concept around polysaccharide conjugate vaccines? when are they used
- Link polysaccharide to protein for T dependent antibody
production - T cells are activated by peptide, not polysaccharide
- Used for organisms that have surface polysaccharide coats
What are 2 examples of polysaccharide conjugate vaccines?
Pneumococcal polysaccharide conjugate to Diphtheria toxoid,
Hib vaccine
What is a positive for conjugated polysaccharide vaccines?
Activates good antibody response to polysaccharide residues
What are 2 negatives for conjugated polysaccharide vaccines?
weakly immunogenic
limited induction of cell mediated immunity
What is the main concept of virus like particle vaccines?
construct multiprotein structures that mimic the organization and conformation of authentic native viruses
- lack the genome
What are 2 examples of virus like particle vaccines?
HPV vaccines (Gardasil®, Cervarix®) Hepatitis B (Engerix®)
What are 4 pros to virus like particle vaccines?
- safe, no risk of infection
- wide spectrum of antigens
- activated cell mediated and humoral immunity
- quick to manufacture
What are 5 negatives to virus like particle vaccines?
- complete viral genome sequencing required
- complex manufacturing process
- immunogenicity can vary depending on culture conditions
- may require and adjuvant
- no persistence (need boosting)
What two vaccine requirements drive novel vaccine technologies?
safety and efficacy
What is an adjuvant?
A substance that enhances the immunogenicity of an antigen
what do adjuvants stimulate
the innate immune recognition of an antigen
What do some antigens have to activate the innate immune response?
Molecular defined structures that mimic PAMPs or DAMPs and stimulate the innate immune systems PRRs
What is another form of adjuvant ? how does it work ?
oil/ liposome which prolongs stability and interactions of antigens with the immune system
what are DNA vaccines based on?
plasmid DNA that encodes antigenic proteins
Where are DNA vaccines injected into and what does it cause?
into the muscle of the recipient causes the proteins to be expressed by muscle cells and adjacent dendritic cells
What kind of immunity do DNA vaccines induce? is it short or long lasting? why?
humoral and cell-mediated immunity that is long- lasting due to prolonged expression of the antigens
How are recombinant vector vaccines produced?
inserting genes coding for the major antigens of a pathogen into attenuated viruses or bacteria
What is a commonly used virus for viral vectored vaccines?
Vaccina
What virus was used to develop an Ebola vaccine
VSV
What are peptide based vaccines made using?
Smallest synthetic epitope that can generate an immune response
- for t cells this is 9-10 amino acids
What is required for peptide based vaccines?
adjuvants and formulations
What is the relative level of safety of peptide based vaccines?
highest level of safety
What are peptide based vaccines commonly used to target? what response?
T cell responses
- common in cancer immunology
What are the two types of cancer vaccines?
- Prophylactic
2. Therapeutic
What do prophylactic cancer vaccines usually target? whats an example?
infections that have been
shown to cause cancer
-Guardasil (HPV)
What do therapeutic cancer vaccines target?
target the cancer/tumour at its most vulnerable (ie. After surgery and chemo) - treat with a vaccine to stimulate the immune system to keep the tumor in remission
