Immunity Against Infection III

Question 1

What are the 4 evasion mechanisms of pathogens

Answer 1

Concealment of antigens

Antigenic variation

Immunosuppression

Interference with effectors

Question 2

Which viruses conceal antigens through stopping MHC I presentation

Answer 2

Herpes simplex virus (cold sore)

Question 3

What other 2 ways can antigen concealment occur

Answer 3

Privileged sites

Uptake of host molecules to disguise foreign recognition

Question 4

Which virus lays dormant in the cns privileged site until times of stress etc

Answer 4

Herpes zoster virus (chicken pox/shingles)

Question 5

Give an example of uptake of host molecules to conceal antigens

Answer 5

Schistosomes parasites will remove molecules off cells so they aren’t recognised

Question 6

Which pathogen has 23 varied antigens / polysaccharides causing evading mechanisms

Answer 6

Streptococcus

Question 7

What are the 2 strep vaccines

Answer 7

Pneumovax- uses ti 2 response to release antibodies via 23 different polysaccharide antibodies

Prevnar 13- conjugates polysaccharide with diphtheria toxoid for a TD response

Question 8

Why isn’t pneumovax effective in kids

Answer 8

Don’t have a ti 2 response in b cells so can’t produce antibodies for the streptococcus polysaccharide ag

Question 9

Antigenic drift and shift eg in influenza is another type of antigen variation causing evasion. Explain difference

Answer 9

Drift is a slight mutation in hemagluttinin and neuraminidase

Shift is where two diff animal strains eg pig and bird exchange rna.

Both Can’t be recognised by antibodies at all so can’t stop influenza entrance

Question 10

Which parasite can gene switch antigen for evasion mechanism

Answer 10

Trypanosomes (cause African sleeping sickness)

Question 11

What antigen is genetically rearranged and unrecognisable by antibodies in trypanosoma

Answer 11

Vsg

Variant specific glycoprotein

Question 12

How does hiv cause immunosuppression (3rd evasion mechanism)

Answer 12

Attacks CD4, macrophages and dendrites

Question 13

Which 2 pathogens cause increased t reg stimulated immunosuppression (t regs stops th1 and th2 and immunity)

Answer 13

H pylori (surface bacteria)

Leishmania (ic parasite)

Question 14

What is the marker for t reg levels when detecting h pylori and leishmania

Answer 14

Cd25 and CD4

Question 15

How do measles cause immunosuppression

Answer 15

Infect dendritic cells (stop T cell stimulation) (by stopping MHC I and II)

Prevent il 12 release (stops th1 response and nk)

Question 16

How do strep and neisseria interfere with evading mechanism to adhere to epithelial surfaces

Answer 16

They contain iga proteases. Degrades iga so they can adhere to surfaces

Question 17

How does staphylococcus interfere with antibodies

Answer 17

Staphylococcus protein A binds to fc portion of antibodies

Causes antibodies to not activate complement / opsonisation

Question 18

Which virus interferes with complement and inhibits it

Answer 18

Small pox/vaccinia

Question 19

Which parasite prevents c3a and c5a via interfering with complement

Answer 19

Pseudomonas

Question 20

Which cytokine can smallpox interfere with and inhibit

Answer 20

Ifn y- stops th1 response eg macrophages,CD8 and NK

Question 21

Which virus can produce its own suppressive il10 cytokine (usually from t regs)

Answer 21

Epstein Barr

Question 22

How does mycobacterium interfere with effector mechanism

Answer 22

Stops phagocytosis via stopping phagosome and lysosome fusion

Question 23

What is pathology through innate and adaptive responses called

Answer 23

Immunopathology

Question 24

How does lps binding to tlr4 in innate cause systemic issues

Answer 24

Causes macrophage to release cytokines like il 1, tnf a

These cause fever, endotoxic shock, cytokine storm of systemic inflammation, causes dic, drop in circulation by increasing vascular permeability to cause inflammation

Question 25

How is granulomas an example of immunopathology

Answer 25

Macrophages aggregate in response to mycobacterium tb and leprae

Causes necrosis in cell

Question 26

What immunopathology causes skin rashes in measles

Answer 26

T cells activation

Question 27

How can antibodies to strep protein be an issue / immunopathology

Answer 27

They can attack heart muscle to cause rheumatic fever

Question 28

How does Ebola interfere with effector mechanisms / cause immunosuppression

Answer 28

Infect dendrites and macrophages, T cells and NK cells

Dendrites and macrophages can’t present MHC

Also interferes with type 1 ifn