Memory and vaccination

Question 1

primary immune response

Answer 1

first time individual’s immune system is exposed to a pathogen
before exposed to antigen they are referred as naive
this is response to infection or vaccination

Question 2

secondary immune response

Answer 2

second, third, fourth etc time an individuals immune system is exposed to the pathogen
cells are antigen experienced and have immunological memory
is qualitatively and quantitatively improved
often asymptomatic or mild disease

Question 3

what does immune memory involve

Answer 3

T cells
b cells
antibodies
can last decades

Question 4

activation of B cells

Answer 4

3 signals:
1. antigen and mhc
2. costimulation
3. cytokines

Question 5

characteristics of memory B cells

Answer 5

produce higher affinity antibody than plasma cells
produce class switched antibody
produce antibody quickly
can re-enter germinal centres and undergo another round of somatic hypermutation and affinity mutation
higher levels of MHC and costimulatory molecules to attract T cell help

Question 6

unimmunized donor
primary response

Answer 6

frequency of antigen-specific B cells 1:10^4/10^5
more IgM than IgG
low antibody affinity
low somatic hypermutation

Question 7

immunised donor
secondary response

Answer 7

frequency of antigen-specific B cells 1:10^2/10^3
IgG and IgA produced
high antibody affinity
high somatic hypermutation

Question 8

2 subsets of memory T cells

Answer 8

central
effector

Question 9

molecules that naive T cells make

Question 10

molecules effector T cells make

Question 11

molecules memory T cells make

Question 12

what activates naive T cells

Answer 12

dendritic cells in the lymph nodes
have CCR7 and CD45RA on surface

Question 13

what happens after naive T cell activation

Answer 13

effector T cells differentiate and secrete cytokines, express cytokine receptors
memory cells derive directly from some effector T cells

Question 14

what happens to most effector T cells

Answer 14

die by apoptosis

Question 15

what do some memory T cells seem to be

Answer 15

quiescent or anergic
can’t respond to antigen

Question 16

how do memory T cells survive

Answer 16

because they can respond to survival signals from cytokines IL-7 and/or IL-15

Question 17

central memory T cells

Answer 17

express CCR7
remain in lymphoid tissue
behave more like naive cells
need antigen presented to them again
long lived precursors that take longer to respond
not committed to Th1 or Th2 type

Question 18

effector memory T cells

Answer 18

lack CCR7 and migrate to tissues
immediate expansion on re-infeciton
express receptors for inflammatory chemokine so can be recruited to inflammation rapidly
produce IFN gamma, IL-4 or IL-5 quickly

committed to a lineage Th1,17 or 2

Question 19

trained immunity

Answer 19

innate immune system may display memory
not antigen specific and is shorter lived
innate memory= trained
involved epigenetic changes, metabolic changes and improved effector functions

Question 20

how can memory be induced by vaccination

Answer 20

as a surrogate for primary infection
seek to generate antibodies to prevent damage by pathogen toxins or neutralise pathogen to stop infection
vaccine needs to incorporate antigen that the body will recognise as foreign and drive B cell activation and antibody production

Question 21

vaccines and T cells

Answer 21

best vaccine also triggers T cell immunity
essential in effective vaccination against viruses
if antigen isn’t cleared by innate immune system then vaccine won’t work

Question 22

measles percentage vaccinated for herd immunity

Answer 22

93-95%

Question 23

vaccine requirements

Answer 23

safe-mustnt cause illness or death
protective- must protect against illness caused by live pathogen
sustained protection-ideally last several years

Question 24

practical considerations for vaccinations

Answer 24

low cost per dose
biological stability
ease of administration
low side effects

Question 25

types of vaccine

Answer 25

mRNA live attenuated pathogen subunit or toxoid synthetic or conjugated whole inactivated pathogen

Question 26

live attenuated pathogen

Answer 26

typically viral vaccines e.g. rotavirus and MMR can replicate which. provides strong stimulation to the immune system

Question 27

1st way live attenuated vaccines are produced

Answer 27

1. pathogenic virus is isolated and cultured in human cells 2. used to infect a different animals cells e.g. monkey 3. virus acquires mutations to allow it to grow well in monkey cells 4. mutations then reduce its ability to grow in human cells when used as a vaccine

Question 28

2nd way live attenuated vaccines are produced

Answer 28

isolate the pathogenic virus identify the virulence genes (receptor binding proteins, virulence proteins, core structural proteins) mutate OR delete the virulence genes to attenuate the virus

Question 29

inactive pathogen

Answer 29

whole pathogens are inactivated/dead e.g. flu and polio

Question 30

how are inactive pathogen vaccines produced

Answer 30

1. isolate the live pathogenic organism 2. inactivate the pathogen with either heat or formaldehyde 3. pathogen is structurally intact but inactive, can't replicate in the body

Question 31

conjugate vaccines

Answer 31

some antigens can't effectively induce a memory response on their own, specifically in children combine and antigen recognised by the B cell (polysaccharide) second antigen that will induce T cell help (protein toxoid) meningitis C

Question 32

producing conjugate vaccines

Answer 32

1. B cell recognises polysaccharide and takes up whole vaccine molecule presents polypeptides of this and the toxoid on MHC2 2. T cell recognises the toxoid being presented by B cell and provides stimulation to cause B cell activation and class switching 3. B cell produces antibodies to polysaccharide that its receptor recognised and develops a memory response

Question 33

pathogen components

Answer 33

include subunit and toxoid vaccines use small pieces of pathogens combined with adjuvant to induce immunity

Question 34

toxoid vaccines

Answer 34

1. some bacteria exert their harmful effects through toxin production 2. toxins are purified from the bacteria and inactivated 3. now referred to as toxoids nd can induce immune system to produce antibodies against toxin without causing disease tetanus

Question 35

subunit vaccines

Answer 35

1. pathogenic bacteria are isolated 2. specific protein from the organism which causes immune response is isolated 3. used in a vaccine to stimulate dendritic cells to take it up and present antigen whooping cough (pertussis)

Question 36

DNA/RNA vaccines

Answer 36

1. produce RNA/DNA strand which codes for pathogenic protein and inoculate it into the body's cells, usually muscles 2. cells take up nucleic acid, produce protein and express it on their surface and/or secrete it 3. immune system recognises this as foreign and mounts a response (often both CD8+ and CD4+) COVID-19 and prostate cancer

Question 37

advantages of DNA/RNA vaccines

Answer 37

potentially effective against cancers antigen presentation by MHC1 and MHC2 long term persistence of the antigen

Question 38

disadvantages of DNA/RNA vaccines

Answer 38

possibility of inducing tolerance (switching immune responses off) if insufficient adjuvant is given

Question 39

adjuvants

Answer 39

compounds used to enhance immune response e.g. alum, bacterial cell wall components and mineral salts

Question 40

what are adjuvants mixed with antigens to do

Answer 40

enhance immunogenicity by giving a danger signal reduce amount of antigen needed aid delivery at the mucosa

Question 41

future of vaccination

Answer 41

reverse vaccinology (meningitis B vaccine) CAR T cells (in leukaemia) dendritic cell vaccines (in rheumatoid Arthritis and cancer)

Question 42

reverse vaccinologu

Answer 42

1. examine the genome of the pathogen and try and identify novel antigens (usually surface proteins) 2. synthetically produce the protein 3. test for an effective immune response and antibody production

Question 43

current approved covid-19 vaccines in the UK

Answer 43

moderna- mRNA pfizer- mRNA nuvaxovid- protein subunit AstraZeneca- non replicating viral vector Janssen- non replicating viral vector valneva- inactive virus