Memory and Escape

Question 1

what is immunological memory caused by?

Answer 1

long lived antibodies and memory cells, re-exposure, affinity maturation, class switches

Question 2

what are the infection processes of bacteria?

Answer 2

attaching to host cells, proliferation, invasion of host tissues

Question 3

how does the host defend against bacteria attachment?

Answer 3

blocked by secretory IgA

Question 4

how does bacteria evade IgA secretion?

Answer 4

protease splits the IgA dimers, antigenic variation

Question 5

how does the host defend against proliferation?

Answer 5

phagocytosis, complement-mediated lysis

Question 6

how do bacteria try and evade phagocytosis?

Answer 6

surface inhibitors, survive within the phagocytic cell, causes apoptosis within macrophages

Question 7

how do bacteria try and evade compliment-mediated lysis?

Answer 7

resistance of gram-positive bacteria as they don’t allow compliment protein to bind to its surface

Question 8

how does bacteria prevent MAC forming?

Answer 8

inserting long side chains which interfere with compliment proteins

Question 9

how does the host cell try and protect invasion of host tissues?

Answer 9

Ab-mediated agglutination

Question 10

how do bacteria evade ab-mediated agglutination?

Answer 10

secrete elastase with inactivates agglutination, release hyaluronidase which enhances invasiveness

Question 11

what are some other bacterial escape strategies?

Answer 11

cell wall resistant to enzymes, secreted toxins to repel phagocytes, enzymes secreted to inhibit host response

Question 12

how do bacteria interfere with the host response?

Answer 12

inhibit inflammatory response, break cement between cells, coat bacterium with fibrin layer

Question 13

what does IgA do in response to viruses?

Answer 13

blocks binding to cells

Question 14

what antibodies block the fusion of viral envelope and cell membrane?

Answer 14

IgG, IgM, IgA

Question 15

what antibodies cause agglutination of a virus?

Answer 15

IgM

Question 16

what does complement do in response to viruses?

Answer 16

assist opsonisation, produces MACs which kills infected host cells

Question 17

what responses to viruses are involved in the humoral response?

Answer 17

antibodies and complement

Question 18

what responses to viruses are cell mediated?

Answer 18

gamma interferon, Tc cells, NK cells and macrophages

Question 19

what does the gamma interferon do in response to viruses?

Answer 19

stops viral infected cells from producing new copies

Question 20

what do Tc cells do in response to viruses?

Answer 20

kill cells which have been infected with the virus

Question 21

what do NK cells and macrophages do in response to viruses?

Answer 21

kill cells that have been infected by the virus

Question 22

how does hepatitis C survive?

Answer 22

blocks protein kinase and alpha and beta interferons

Question 23

how does the herpes simple survive?

Answer 23

early protein inhibits transporter molecules for antigen processing to MHC-I receptors

Question 24

how do adenoviruses survive?

Answer 24

reduce expression of MHC-I and so reduced presentation with CD8 to T cells

Question 25

what is antigenic drift?

Answer 25

point mutations in genes that cause a change in structure of surface glycoproteins so antibodies no longer complementary

Question 26

what is antigenic shift?

Answer 26

surface antigens that are complementary are altered by combination of genomes from two different strains so secondary response isn’t possible

Question 27

what are the parasite escape strategies?

Answer 27

have diverse structure, survive phagocytosis, antigenic drift, can disguise as host cells