microbes and the immune system Flashcards
how and what parasites evade destruction by immune systum using location
-intracellular and cysts
1) intracellular
plasmodium
toxoplasma
T. cruzi
leishmania
2) cysts- bug secretes a tough shell around it to prevent immune system from getting to it.
toxoplasma
echinococcus
how parasites use antigenic mimicry to evade immune system
we normally don’t have immune response against to our own cells therefore parasites cover themselves in our antigens so immune system doesn’t recognise foreign antigens.
schistosoma
how parasites use immunosuppression and antigenic variation to evade immune system
1) suppression of bodies immune system to prevent them from fighting parasites
T. cruzi- salvia
T. Brucei- vector faeces
filarial worms
schistosoma
2) changes antigens that presents to immune system
T. Brucei
plasmodium
how antigenic variation is employed by African trypanosomes (T. Bruci) e.g. sleepy sickness.
-surface coat of parasite
-how they stay ahead of immune system
parasite has VSG (variance surface glycoprotein coat) to protect them.
the parasites repeatedly proliferates and crashes, to change their coat over and over.
the parasite has over 1000 genes encoding different versions of VSG coat. and can express 1 gene at a time through gene duplication
the expression of VSG is constantly changing
= prolonged infection
what immunological response has evolved for helminths worm infection
more effective against micro-organisms than macro organism
igE- allergys
activation of mast cells and basophils
binds helminths and recruits eosinophils to the worms. eosinophils release proteins.
what is the worm theory of protein ES-62?
Protein ES-62 is secreted by parasitic worms of rodent and the protein triggers anti-inflammatory immune response
protein ES-62 when pure and injected can decrease inflammation.
what are the four types of class switching antibodies
IgM- low affinity antibody
IgG- most abundant in serum
IgE- allergy and anti-worm responses
igA- found a mucosal sites e.g. respiratory tracts and gut
what is the germinal centre?
B lymphocytes exposed to antigens develop the ability to produce high-affinity antibodies.
and memory cells and long lived plasma cells
how to create a live attenuated vaccine?
-what is host attenuation process
1) grow virus and select against different virus using monkey cells. virus can be used in a vaccine as it now cannot grow on human cells.
host- created weakened form of virus
1962 polio was eradicated in England and Whales by what vaccine?
then what happened when Salk killed vaccine was introduced in 2004?
sabin vaccine (oral vaccine)
more polio infection after switching from oral to killed vaccine
how B cells and T cell recognise different forms of antigen?
b cell- the receptor binds to antigen which activates B cells. no accessory cell required
T cells recognise processed antigen presented on MHC molecules on surface of antigen presenting cells.
CD8 T cell (killer) see short peptide in MHC class 1 molecules
CD4 T cell (helper) see longer peptide in MHC class 2 molecules
where does T and B cell activation take place?
secondary lymphoid organs
paracortex or T cell zone is where dendritic cells from tissue meet naive CD4 and CD8 T cells
B cell follicles: where B cells and found and respond to antigen
what is clonal selection of T cells?
the selection of T cells with the right T cell receptor recognises the peptide and becomes activated and proliferates =
lead to a large number of T cells with the right receptors
explain what naive CD4- helper cell subunits do to get rid of pathogens (naive T cell)
T-Helper 1
T-Helper 2
T-Helper 17
1- anti viral response, innate immune cells via cytokines
2- signals from damage caused by worms. enhances mucus response and wound healing via cytokines
17- activates neutrophils and production of antimicrobial molecules via cytokines
release inflammatory cytokines
-releases toxic granules which contain perforin to punch holes in target cells and trigger apoptosis.
