20. Prevention and Cure

Question 1

name 3 physical barriers to infection

Answer 1

mucus (ciliary action)

macrophages on the surfaces of the respiratory tract

acidic pH of the stomach

Question 2

what are the 3 elements of intrinsic immunity

Answer 2

dicer system

PAMPs

interferons

Question 3

how does the dicer system work

Answer 3

double stranded RNA genomes are recognised by dicer proteins

these are then cleaved into pieces which are then catalysed further

Question 4

what 2 pathways catalyse RNA fragments further following action of dicer proteins

Answer 4

Argonaut and RISC pathways

Question 5

how do PAMPs bring about an immune response

Answer 5

detect the infection and recruit adaptor molecules via signalling cascades

phosphorylation of IRF3 or IRF7 forms a dimer that binds to promotor regions in the nucleus = gene expression

this process releases interferons

Question 6

what do secreted interferons do?

Answer 6

bind to receptors on adjacent cells, activating the STAT pathway

STAT pathway = gene transcription

this primes neighbouring cells to fight viruses which have not yet arrived

Question 7

name 3 elements of acquired immunity

Answer 7

antibodies
cytotoxin t-cell activation
t- helper cells

Question 8

what feature of antibodies make it ideal for targeting pathogens

Answer 8

hyper variability in DNA mechanisms = can easily rearrange to target new pathogens

a great quantity can be produced very quickly

Question 9

how are cytotoxic t-cells activated

Answer 9

an infected cell processes the virus antigen, presenting it on their surface

this is recognised by t-cell receptors = activating the cytotoxic t-cell

Question 10

what class of molecules does the APC present to the t-helper cell

Answer 10

MHC class II

Question 11

what are t-helper cell receptors in association with

Answer 11

CD4 molecules

Question 12

what are cytotoxic t-cell receptors in association with

Answer 12

CD8 molecules

Question 13

what does the APC produce that activates the t-helper cell

Answer 13

interleukins

Question 14

name 3 molecules that type 1 t-helper cells produce

Answer 14

interleukins 4
interferon gamma
interleukin 5

Question 15

what does interleukin 4 stimulate

Answer 15

the conversion of naive helper T cells into t-helper type II cells

Question 16

what else is interleukin 4 responsible for

Answer 16

negative feedback loops = inhibiting the early stages so to prevent a cytokine storm

Question 17

what is the consequences of a cytokine storm

Answer 17

overproduction of cytokines - tissue damage

Question 18

HIV destroys t-helper cells: what does this mean?

Answer 18

cytotoxic t-cell response and antibody response is inadequate

Question 19

what produces antibodies

Answer 19

B lymphocytes (B cells)

Question 20

how does a vaccination work

Answer 20

dead or inactive viral antigens enter the body stimulating an immune response

acquired immunity wanes before a secondary reinfection occurs. in the case of a secondary reinfection: immediate antibody production counteracts the effects of the virus

Question 21

what disease did the vaccination programme prevent in the US

Answer 21

poliomyelitis

Question 22

describe the poliomyelitis vaccine

Answer 22

attenuated vaccine: contains a live virus which is mutated to remove its ability to cause disease

Question 23

where does the attenuated polio virus replicate

Answer 23

in the intestine before being excreted

Question 24

how can individuals acquire passive immunisation

Answer 24

where sewage enters the water supply or the faecal oral route

Question 25

since 2000 how many cases of polio, what are the majority of these cases

Answer 25

760 cases

- vaccine-derived polio

Question 26

what is one of the most successful vaccines

Answer 26

yellow fever virus

- no danger of reversion (becoming pathogenic again)

Question 27

name 2 other approaches to vaccination

Answer 27

virus-like particle

peptide cocktail vaccines

Question 28

explain how virus-like particle vaccines work

Answer 28

contains only part of the virus that will raise an immune response

Question 29

how do recombinant vaccines work

Answer 29

combine viral antigens in non-pathogenic vectord

Question 30

evaluate peptide cocktail vaccines

Answer 30

pros: safe, wide coverage, cheap
cons: how do we deliver it, effectiveness??

Question 31

what is acyclovir active against

Answer 31

herpes simplex virus

Question 32

how does acyclovir work

Answer 32

inhibits viral DNA synthesis

Question 33

what is required to phosphorylate acyclovir, where is this found>=?

Answer 33

thymidine kinase enzyme

only found in viruses - and not in human cells = harmless to host

Question 34

can resistance to antivirals such as acyclovir arise?

Answer 34

yes - means derivatives have had to been engineered

Question 35

name 3 antivirals

Answer 35

acyclovir
ganiclovir
penciclovir

Question 36

name 3 antivirals

Answer 36

acyclovir
ganiclovir
ribavirin

Question 37

what is ribavirin active against

Answer 37

viral RNA polymerase

Question 38

what disease does saquniavir target

Answer 38

HIV-1 protease enzyme = inhibits its action

Question 39

what is PREP

Answer 39

a cocktail of drugs used to treat aids

Question 40

what is the major component of PREP

Answer 40

tenofovir

Question 41

what is a disadvantage of PREP

Answer 41

could result in the evolution of resistant strains

Question 42

what does PREP do

Answer 42

reduces the likelihood of the disease taking hold

- prevents the disease before exposure has occurred

Question 43

how has vaccine-derived polio virus spread

Answer 43

vaccine included a weakened strain of the virus that has since changed over time becoming more like the original virus

can spread easily to those who remain unvaccinated who come into contact with infected secretions

Question 44

which vaccine does vaccine-derived polio virus originate from

Answer 44

the oral polio vaccine