lecture 18

Question 1

what are the 5 key events during infection

Answer 1

1) exposure to reservoir of organism
2) transmission to person
3) adhesion to initial site of infection
4) overcome barriers to establish infection
5) spread to other sites by changing initial site of infection

Question 2

what are the 3 microbial factors

Answer 2

dose, type of organism and route of entry

Question 3

what are the 3 host factors

Answer 3

integrity of innate barriers, competence of adaptive immune system, genetic capacity to respond to organism

Question 4

what is type of organism as a microbial facor

Answer 4

how our body copes with the virus and what type of virus is it

Question 5

what is dose as a microbial factor

Answer 5

degree of exposure (how large is the dose)

Question 6

what is route of entry as a microbial factor

Answer 6

was it breathed in or ingested

Question 7

what is integrity of innate barriers as a host factor

Answer 7

was there a cut on the hand which allowed for the microbe to come in

Question 8

what is competence of adaptive immune system

Answer 8

is there a previous exposure such as a vaccination

Question 9

what are anatomic barriers

Answer 9

skin, mucosa, respiratory epithelium, intestine, physical protection by bodies of epithelial surfaces

Question 10

what are complement proteins

Answer 10

C3, defensins, chemical and enzymatic systems which act as a antimicrobials near the epithelium

Question 11

what are innate immune cells

Answer 11

macrophages, granulocytes, NJK cells, if the epithelial is breached then innate cells provide rapid response

Question 12

what are adaptive immune cells

Answer 12

slower acting cells needed if prior barriers fall including B cells, T cells and antibodies

Question 13

what do sensor cells do

Answer 13

secrete cytokines that signal to other immune cells, and can lock on to bacteria and engulf them

Question 14

what are TH1 cells

Answer 14

mature helper cells which promote inflammation and provide immunity against viral infections and intracellular bacteria

Question 15

What are TH2 cells

Answer 15

mature helper T cells which promote allergic responses to IgE and provide immunity against extracellular organisms in particular helmiths

Question 16

what are Treg cells

Answer 16

mature helper T cells that control TH1 and TH2 cells and ensure we dont respond to self

Question 17

what happens when antibodies and complement work together

Answer 17

enhance bacteria destruction by phagocytosis

Question 18

what are the 3 pathways which activate complement host defense

Answer 18

lectin pathway, alternative pathway and classical pathway

Question 19

what is the lectin pathway

Answer 19

lectin binds to pathogen surface and mannose binding protein and ficolins recognise receptors and bind carbohydrates on pathogen surface.

Question 20

what is classical pathway

Answer 20

antibody mediated pathway in which specific antibodies will recognise the outside of the bacteria and lead to C1q binding to the antibody and pathogen surface

Question 21

what is the alternative pathway

Answer 21

some pathogen surfaces C3 undergo spontaneous hydrolysis to detect pathogens, the C3 then breaks apart and the process of C3 binding to the pathogen surface occurs

Question 22

what happens once complement defence system is activated

Answer 22

opsonisation of pathogen occurs (phagocytosis)

Question 23

what do all 3 pathways lead to

Answer 23

recruitment of inflammtory cells (chemotaxis) and killing of pathogens (lysis)

Question 24

when do all these systems occur

Answer 24

at the same time at different parts of the pathogen surface resulting in C3 cleavage

Question 25

what is C3 cleavage

Answer 25

activation of complement

Question 26

what happens when C3 cleaves

Answer 26

it also cleaves to C3A and C3B

Question 27

what is C3B

Answer 27

C3B binds to surface of the pathogen

Question 28

what is C3A

Answer 28

C3A floats around as an immune signalling molecule

Question 29

what mechanisms occur when C3 is cleaved

Answer 29

1) C3B and C5A signal the recuitment of phagocytic cells and promote inflammation at the site of infection
2) opsonisation of pathogens
3) lysis by formation of spore which can punch holes in surface of some bacteria

Question 30

what is a capsule

Answer 30

layer that bacteria can have on their outside

Question 31

how does a capsule work

Answer 31

its negativly charged so it creates a physical way for bacteria to repel the phagocyte as a phagocyte is also negativly charged

Question 32

what is intracellular growth

Answer 32

being able to divide and grow inside the body

Question 33

what are type 1 interferons

Answer 33

antiviral mechanism which provides a response when cells become infected

Question 34

how does type 1 interferons work for neighbouring cells

Answer 34

interferons are sent out into the environment by infected cells which allow neighbouring cells to turn on some processes which make them more likely to be infected by the virus (down regulate molecules and receptors)

Question 35

how does type 1 interferons work for NK cells

Answer 35

interferon type 1 can provide a signal to NK cells to kill neighboring infected cells

Question 36

how do some viruses interfere with interferon response

Answer 36

by dampening interferon secreation by infected cells and by blocking the antiviral state of neighbouring cells from being activated

Question 37

what happens if the interferon secretion is delayed

Answer 37

it can do more harm than good