20. Prevention and Cure Flashcards
name 3 physical barriers to infection
mucus (ciliary action)
macrophages on the surfaces of the respiratory tract
acidic pH of the stomach
what are the 3 elements of intrinsic immunity
dicer system
PAMPs
interferons
how does the dicer system work
double stranded RNA genomes are recognised by dicer proteins
these are then cleaved into pieces which are then catalysed further
what 2 pathways catalyse RNA fragments further following action of dicer proteins
Argonaut and RISC pathways
how do PAMPs bring about an immune response
detect the infection and recruit adaptor molecules via signalling cascades
phosphorylation of IRF3 or IRF7 forms a dimer that binds to promotor regions in the nucleus = gene expression
this process releases interferons
what do secreted interferons do?
bind to receptors on adjacent cells, activating the STAT pathway
STAT pathway = gene transcription
this primes neighbouring cells to fight viruses which have not yet arrived
name 3 elements of acquired immunity
antibodies
cytotoxin t-cell activation
t- helper cells
what feature of antibodies make it ideal for targeting pathogens
hyper variability in DNA mechanisms = can easily rearrange to target new pathogens
a great quantity can be produced very quickly
how are cytotoxic t-cells activated
an infected cell processes the virus antigen, presenting it on their surface
this is recognised by t-cell receptors = activating the cytotoxic t-cell
what class of molecules does the APC present to the t-helper cell
MHC class II
what are t-helper cell receptors in association with
CD4 molecules
what are cytotoxic t-cell receptors in association with
CD8 molecules
what does the APC produce that activates the t-helper cell
interleukins
name 3 molecules that type 1 t-helper cells produce
interleukins 4
interferon gamma
interleukin 5
what does interleukin 4 stimulate
the conversion of naive helper T cells into t-helper type II cells
what else is interleukin 4 responsible for
negative feedback loops = inhibiting the early stages so to prevent a cytokine storm
what is the consequences of a cytokine storm
overproduction of cytokines - tissue damage
HIV destroys t-helper cells: what does this mean?
cytotoxic t-cell response and antibody response is inadequate
what produces antibodies
B lymphocytes (B cells)
how does a vaccination work
dead or inactive viral antigens enter the body stimulating an immune response
acquired immunity wanes before a secondary reinfection occurs. in the case of a secondary reinfection: immediate antibody production counteracts the effects of the virus
what disease did the vaccination programme prevent in the US
poliomyelitis
describe the poliomyelitis vaccine
attenuated vaccine: contains a live virus which is mutated to remove its ability to cause disease
where does the attenuated polio virus replicate
in the intestine before being excreted
how can individuals acquire passive immunisation
where sewage enters the water supply or the faecal oral route
