Exam 2- Principles of Immunization Flashcards
what is the goal of active immunization?
generate long-lasting and protective immunization against a specific pathogen to prevent infection and/or disease by that pathogen and eliminates or decreases carriage and/or shedding of the pathogen
what are the two main types of immunization?
active and passive
capsular polysaccharide is the only antigen that protects against an extracellular pathogen and (transmitted by tick bite) that infects the liver, but no other organ. which response will be the most important for protection against the pathogen?
serum antibody response
you would like to prepare a vaccine using the polysaccharide antigen. what do you conjugate it to?
polysaccharide antigen conjugated to a protein carrier with an aluminum phosphate adjuvant
what are the advantages of active immunization?
generates humoral or both humoral and cell-mediated immunity
long term protection due to generation memory and plasma cells
does not lead to serum sickness
what are the disadvantages of active immunity?
time (weeks) to develop immunity
fibrosarcomas can occur in cats- rare
what does passive immunization involve?
transfer preformed antibodies against particular pathogen or toxin
what are the two classes of passive immunization?
natural and acquired passive immunity
when does natural passive immunity occur?
maternal antibodies transferred to fetus via placenta or colostrum
true/false: acquired passive immunity is when purified monoclonal antibodies or immunoglobulins from a different individual are injected into an individual
true
what is the advantage of passive immunization?
immediate benefits
what are the disadvantages of passive immunity?
immunity is short-lived: 2-3 weeks
repeated administration from heterologous species can result in serum sickness
do polysaccharide antigens require conjugation with a carrier protein? why?
alone, mostly induces IgM response: half-life 4-5 days, lack of help from Th cells with class switching
conjugated: effective IgG response, recruits Th cells for class-switching
what is a conjugate vaccine?
vaccine of polysaccharide antigens conjugated with protein carrier molecule
why is it important to know about the transmission route and disease pathogenesis of a pathogen?
to know what reaction a vaccine should induce: mucosal or systemic immune response or both
what type of immunity is important for extracellular pathogens?
humoral immunity
what type of immunity is important for intracellular pathogens?
both humoral and cell-mediated immunity
how can a vaccine induce a long-lasting protective immune response?
long-lived plasma cells
memory Th and memory B cells
memory Tc cells
make antigen available to immune system for sufficient duration
what are adjuvants used for?
decrease amount of antigen and reduce number of doses required to induce protective immunity
induce protective response more rapidly
increase rate of seroconversion in special populations
what are the five mechanisms of action adjuvants may use?
increasing biological half-life of vaccines
upregulation cytokines and chemokines at site injection
increase antigen uptake and presentation to APCs
activation and maturation APC
activation inflammasomes
what adjuvants are most widely used in human and veterinary medicine?
aluminum adjuvants
what response do aluminum-containing adjuvants induce?
preferentially Th2 responses
what adjuvants have been implicated in development of feline fibrosarcoma?
aluminum adjuvants
what do water-in-oil emulsion adjuvants consist of?
heat-killed Mycobacterium tuberculosis in non-metabolizable oils
what type of response does a complete Freund’s adjuvant induce?
mostly Th1
incomplete: mostly Th2
are injection site reactions common with water-in-oil adjuvants?
yes, fairly common
what does the oil-in-water adjuvant MF59 consist of?
squalene oil
Tween 80 and Span 85
what type of response does MF59 lead to?
balanced Th1 and Th2 response
half life is 42 hours
what is required to form cage-like complexes?
saponin
cholesterol
phospholipid
immunogen
what vaccines is the adjuvant QS-21 used in?
feline leukemia virus (FeLV)
canine Lyme disease vaccine
from where are live attenuated or modified live vaccines derived from?
“wild” or disease-causing viruses or bacteria
how are wild viruses or bacteria weakened or attenuated?
repeated in vitro culturing
cold-adapted and temperature sensitive
defined genetic modification
mutagenesis by chemicals or irradiation
is adjuvant required for live attenuated or modified live vaccines?
no
can live attenuated or modified live vaccines convert back to virulent form?
yes
who should not receive live vaccines, if anyone?
individuals with weakened immune systems
are inactive or killed vaccines safer than live vaccines?
yes
killed bacterial vaccines are also called “_____________”
bacterins
what are the advantages of subunit or antigen vaccines?
very safe
unable to revert back to cause disease
with good adjuvant, can induce humoral or both humoral and cell-mediated immunity
true/false: one advantage of a DNA vaccine is that antigen is presented by both MHC class I and MHC class II molecules
true
why is an RNA vaccine safer than a DNA vaccine?
it poses no risk of disrupting cell’s natural DNA sequence
how does a vector vaccine differ from a live vaccine?
only a gene encoding for a protective antigen of a pathogen is inserted into an attenuated virus or bacterium
when are autogenous vaccines used?
within a herd, using a pathogen obtained from an animal in the herd
what types of hypersensitivity reactions can vaccines induce?
types I, II, and IV hypersensitivity reactions
for maternal antibodies, what are the three possible mechanisms of antibody interreference?
antigen removal by macrophages
B cell inhibition through epitope masking
B cell inhibition through cross-link of BCR with Fc-gamma-RIIB
what can repeated administration of antibodies from a heterologous species result in?
serum sickness
are polysaccharide antigens in vaccines good at eliciting a cell-mediated response?
no
