Molecular strategies used by pathogens

Question 1

what are the host defences against attachment

Answer 1

rinsed by surface secretions
ciliary sweeping action
produce secretory IgA

Question 2

what are the microbial strategies for attachment

Answer 2

bind firmly to surface

inactivate IgA by IgA protease

Question 3

what are the host defences against invasion

Answer 3

cell membrane poses barrier

Question 4

what are the microbial strategies for invasion

Answer 4

traverse membrane (fusion proteins), trigger uptake by phagocyte (inject proteins that trigger uptake) and resist killing

Question 5

what bacteria is associated with membrane ruffled

Answer 5

Salmonella

Question 6

what are the microbial strategies for intracellular survival against phagocytosis

Answer 6

block phagocyte chemotaxis, kill phagocyte, inhibit phagocytosis and lysosome fusion, resist killing, multiply inside

Question 7

what are leukocidins

Answer 7

a type of pore forming toxin produced by some bacteria as a defense against phagocytes etc

Question 8

what is a host defence against microbe intracellular survival

Answer 8

phagocytosis
restriction of Fe(III)
production of reactive oxygen and nitrogen species

Question 9

what do microbes do against the host defence of restricting iron

Answer 9

microbe scavenges iron in competition with host by producing siderophores (binding Fe(III) with high affinity)

Question 10

what molecular strategies does the microbe have against production of reactive oxygen and nitrogen species

Answer 10

diverts vesicles of NADPH oxidase so they don’t fuse
produce enzymes to inactivate ROS and RNS
hydroxyl radical release
step wise reduction of oxygen to decrease reactive species

Question 11

what host defences are there against extracellular survival

Answer 11

production of complement and antimicrobial peptides and antibodies
antimicrobial cell-mediated and immune responses

Question 12

what pathogens cause actin rearrangement

Answer 12

ecoli0157
salmonella
listeria
vaccina virus

Question 13

give an example of a pathogenic group that goes through antigenic shift and drift

Answer 13

type A influenza viruses go through both

Question 14

what are the four broad stages of infection

Answer 14

encounter/attachment
entry/establishment
colonisation
spread/multiplication/(damage)/shedding

Question 15

give three microbial strategies to production of complement and antimicrobial peptides

Answer 15

microbes alter their cell surfaces (sialylation); inactivate complement (proteases); bind complement non productively (C3b receptor)

Question 16

how do ecoli protect against complement and antimicrobial peptides

Answer 16

membrane blebbing sequestering camp from the cell membrane

Question 17

what is an epitope

Answer 17

the part of the antigen that is recognised by the immune system - 3D