III - vaccines Flashcards
what is measles and what is it caused by
respiratory system infection
caused by a paramyxovirus
what is herd immunity
immunity developed by a group of vaccinated individuals
what is amantadine and how does it effect influenza virus
antiviral
blocks M2 ion channels on the envelope of the virus
prevents viral genetic material from exiting the virus
what are zanamivir and oseltamivir and how do they perform their role
they are neuraminidase inhibitors
inhibiting the neuraminidase enzyme prevents budding and therefore the release of new virus from the host cell
function of neuraminidase
cleaves polysaccharides of the host cell surface
what is hemagglutinin
proteins on the surface of influenza
bind to host cell surface
what are both hemagglutinin and neuraminidase
the two main influenza antigens
what are the subtypes of influenza A
H - hemagglutinin - types H1-H18
N - neuraminidase - types N1-N11
what are the lineages of influenza B
yamagata
victoria
what are the 2 mechanisms to generate variations in influenza
antigenic drift
antigenic shift
what is antigenic drift
overtime the amount of point mutations that occur results in an antigen that isn’t recognised by the antibody that recognised the original
what is antigenic shift
when an animal and human influenza infect the same cell
the ssRNA gets rearranged between them
leads to completely different antigens
unrecognised by antibodies
what influenza strain is the swine flu and what type of vaccines have been developed for it
H1N1
inactivated or live attenuated vaccines
what are antigenic drift/shift responsible for
drift - seasonal flu
shift - pandemics
what are the incubation periods of influenza and polio virus
influenza - 1-2 days
polio - 3 days
an effective influenza vaccine must be what
able to maintain high levels of serum antibodies because the disease is already underway before memory B-cells can be activated
what are the advantages/disadvantages of live attenuated vaccines
advantages - stronger immune response
usually lifelong immunity
disadvantages - requires refrigerated storage
may mutate to pathogenic form
what are the advantages/disadvantages of dead/inactivated vaccines
advantages - safer
refrigeration not required
disadvantages - weaker immune response
boosters usually required
list the vaccine types
live attenuated
dead/inactivated
conjugate
toxoid
subunit
what are some live attenuated vaccines
polio
MMR
TB
how is attenuation achieved and explain them
natural attenuation - inoculation (Jenner)
serial passage - select mutants with reduced toxicity
what is chemical mutagenesis
it is a method of attenuating a virus
virus is extracted from a patient and cultured in human cells
they are then used to infect monkey cells
they pick up mutations that allow them to better effect monkey cells
lose ability to grown in human cells
features of the sabin vaccine
given orally
induces IgA, IgG and IgM responses
consists of 3 attenuated serotypes of polio
gives immunity for all 3 strains
requires 2 extra boosters
what is the wild-type progenitor strain genome of sabin made up of and how different is the sabin vaccine
7249 nucleotides
the sabin vaccine is different by only 9 nucleotides
how does recombinant DNA allow for safer live attenuated vaccine production
able to isolate the virulence gene
either delete or mutate it
reversion to virulent form is basically impossible
what key genes of malaria are deleted to produce its vaccine and what is the outcome
deletion of p52 and p36
prevents productive liver infection
what are examples of deactivated vaccines
pertussis
cholera
typhoid
polio
influenza
zika
how is a virus inactivated
application of heat or chemical - formaldehyde or alkylating agents
nucleic acids are destroyed
antigens remain intact
why do inactivated vaccines only produce a humoral response
because pathogen does not replicate
what is the main concept of a subunit vaccine
introduce only a subunit of the pathogen to host (only gp120/41)
what are the 3 main subunits isolated to form a subunit vaccine
toxoids
capsular polysaccharides
recombinant protein antigens
what are examples of subunit vaccines
hepatitis B
streptococcus pneumonia
diphtheria
tetanus
what is the concept of a toxoid vaccine
exotoxin is purified and inactivated via formaldehyde
what are examples of toxoid vaccines
diphtheria
tetanus
what can increase the abilities of macrophages/neutrophils to phagocytose bacteria with the anti-phagocytic properties of their hydrophilic polysaccharide capsule
coating the hydrophilic capsule with complements and antibodies
what is an adjuvant
any material that can increase the humoral and cellular immune response to an antigen
how do adjuvants increase the immune response of inactivated/subunit vaccines
act directly on macrophages/neutrophils and dendritic cells
leads to adaptive immune response
what is the process by which adjuvants stimulate the innate immune system
attract APC’s
stimulate pattern recognition receptors (TLR)
induces inflammasome activation
leads to antigen presentation on MHC molecules
what can be used as an adjuvant
aluminium salts
virosomes
MPL
MF59
what are the potential side-effects of adjuvant use
redness, swelling and pain at injection site
systemic reactions - fever, chills and body ache
how do conjugate vaccines solve the problem of a poor immunogenic response
fuse a highly immunogenic protein to the weak vaccine
give an example of a conjugate vaccine
haemophilus influenza type B (Hib) vaccine
what does Hib cause
bacterial meningitis
what does the conjugate vaccine of Hib consist of
the type b capsular polysaccharide fused to tetanus toxoid - highly immunogenic
what do conjugate vaccines activate and not
activate - T helper and memory B cells
does not activate - memory T cells
