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MICB 308 > Vaccinology > Flashcards

Vaccinology Flashcards

1
Q

vaccine

A
  • something originating from a microorganism that elicits a protective immune response
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2
Q

vaccine outcomes (2)

A
  • can lead to resistance to the disease, but not necessarily resistance to infection
  • can protect against the disease, but not necessarily against transmission
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3
Q

herd immunity

A
  • if most of the population is immune, it will slow down spread of disease and protect those who are susceptible
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4
Q

vaccination: goal (2)

A
  • prevention
  • want to prime the immune response so that the response to the pathogen takes 1-2 days instead of weeks
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5
Q

concentration of antibody response
- first exposure
- second exposure

A
  • during first exposure, the primary immune response has a moderate [Ab]
  • during secondary exposure, the secondary immune response has a high [Ab]
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6
Q

importance of herd immunity: no vaccination (2)

A
  • infection passes from individuals with disease to susceptible individuals
  • spreads throughout the population
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7
Q

importance of herd immunity: vaccine coverage below threshold for herd protection (3)

A
  • infection can still pass too susceptible individuals
  • infection spreads throughout population
  • those vaccinated will be protected
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8
Q

importance of herd immunity: vaccine coverage above threshold for herd protection (2)

A
  • infection cannot spread in the population
  • susceptible individuals are indirectly protected by vaccinated individuals
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9
Q

adjuvants

A
  • compounds that increase or modulate intrinsic immunogenicity of a particular antigen
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10
Q

adjuvants: how can they modulate immunogenicity (3)

A
  • stimulate innate immunity
  • result in potent and persistence immune response
  • influence type of immune response (Th1 vs Th2)
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11
Q

which adjuvants can result in potent and persistent immune response (2)

A
  • Alum
  • TLR agonists (DNA, MPLA)
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12
Q

why type of immune response does Alum elicit

A
  • Th2 response
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13
Q

what topics are included in the study of vaccinology (6)

A
  • what the protective immune response is
  • the correct timing and place for the immune response
  • pathogen serotypes
  • stability of the vaccine
  • age of recipients
  • side-effects and complications
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14
Q

what are possible routes of vaccines (4)

A
  • injection
  • inhalation
  • ingestion
  • subcutaneous
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15
Q

generation of immune response to a vaccine: initial injection (3)

A
  1. adjuvant is bound by PRR
  2. vaccine antigen is taken up by a DC and presented on MHC CII
  3. DC is activated and trafficked to the lymph node
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16
Q

generation of immune response to a vaccine: CD8+ T cell pathway (2)

A
  1. DC presents MHC CI:Ag complex to CD8+ T cell, with some help from activated CD4+ T cell
  2. CD8+ T cell is activated and differentiates into CD8+ effector T cell or CD8+ memory T cell
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17
Q

generation of immune response to a vaccine: CD4+ T cell pathway (6)

A
  1. DC present MHC CII: Ag complex to CD4+ T cell
  2. B cell’s BCR detects soluble vaccine Ag and is activated with CD4+ T cell help
  3. B cell undergoes proliferation and maturation of the antibody response
  4. memory B cell proliferation occurs
  5. plasma cell differentiation and antibody production occurs
  6. long-live plasma cells remain in the bone marrow for future infection
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18
Q

design of vaccines: Pasteur’s Philosophy (3)

A
  1. isolate the organism
  2. inactivate or cripple the organism
  3. inject the inactivated microbe
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19
Q

Pasteur’s Philosophy for vaccine design: inactivation of the organism (2)

A
  • attenuated strains
  • inactivate the microbe by killing it
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20
Q

attenuated strains (2)

A
  • passaging of the microbe on different media or treatment with chemicals
  • strain is alive, but crippled
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21
Q

design of vaccines: subunit vaccines (2)

A
  • purified or inactivated proteins (toxoids)
  • conjugate vaccines
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22
Q

vaccine types: common (4)

A
  • live, attenuated
  • killed, whole organism
  • toxoid
  • subunit
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23
Q

vaccine types: less common (5)

A
  • virus-like particle
  • outer membrane vesicle
  • protein-polysaccharide conjugate
  • viral vectored
  • nucleic acid vaccine
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24
Q

vaccine types: experimental (2)

A
  • bacterial vectored
  • antigen presenting cell
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25
Q

subunit vaccines (4)

A
  • purified protein
  • recombinant protein
  • polysaccharide
  • peptide
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26
Q

viral vectored vaccine

A
  • pathogen gene and viral vector gene contained inside a viral vector
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27
Q

bacterial vectored vaccine

A
  • pathogen gene inside a bacterial vector
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28
Q

new vaccine approaches (3)

A
  • reverse vaccinology
  • DNA and RNA vaccines
  • directed /DNA shuffling
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29
Q

reverse vaccinology (3)

A
  • bioinformatic identification of candidate genes
  • produce and express genes synthetically
  • screen in infections models
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30
Q

reverse vaccinology: candidate gene examples (3)

A
  • extracellular location
  • association with B cell epitopes
  • outer membrane proteins
31
Q

directed evolution

A
  • design and co-screen
32
Q

what is the conventional method of vaccine development (4)

A
  1. cultivate the microbe
  2. purify the components (antigens)
  3. test for immunogenicity
  4. clone genes, express proteins, and purify the proteins
33
Q

what are the downsides of the conventional method of vaccine development (5)

A
  • time consuming
  • bias toward antigens that can be made in large quantities
  • bias as not all antigens expressed during infection will be expressed in lab media
  • may not be able to culture certain microbes
  • hypothesis driven
34
Q

in silico

A
  • experimentation performed by computer
35
Q

reverse vaccinology: step 1 (2)

A
  • rely on bioinformatics for initial screen of pathogen genome
  • in silico, identify putative vaccine candidates
36
Q

what is the difference between the first step of conventional vaccine development vs reverse vaccinology

A
  • conventional methods starts with the pathogen, whereas reverse starts with the pathogen genome
37
Q

what are examples of in silico for reverse vaccinology (3)

A
  • using pSORTB to analyze predicted amino acid sequences to predict protein localization
  • using programs to predict antigenicity and immunogenicity
  • search the epitope database and analysis resource
38
Q

what types of surfaces are usually linked to antigenicity and immunogenicity

A
  • hydrophilic surfaces
39
Q

reverse vaccinology: step 2 (3)

A
  • use PCR to amplify the open reading frames (genes)
  • clone gene into an expression vector to make proteins
  • purify proteins
40
Q

reverse vaccinology: step 3

A
  • immunize model host
  • test for immunogenicity (eg. antibodies)
41
Q

reverse vaccinology: advantages (5)

A
  • relatively fast
  • can be used for non-culturable bacteria
  • no bias as to where/when an antigen is expressed
  • allows us to find low abundance antigens
  • discovery driven research, avoiding limitations of hypothesis driven research
42
Q

reverse vaccinology: disadvantages

A
  • protein folding issues
  • antigen post translational modifications
43
Q

how was reverse vaccinology used to make the meningococcal B vaccine (6)

A
  1. candidates predicted in the whole genome sequence of Neisseria meningitidis
  2. in silico predicted surface expressed proteins
  3. genes expressed, purified and used to immunize mice
  4. genes identified as surface exposed
  5. genes identifies to induce bactericidal antibodies
  6. 3 antigens selected
44
Q

DNA vaccines: advantages (6)

(class slides)

A
  • elicit protective immunity
  • general conformation (shape) of antigen that is expressed is preserved
  • simple, just a plasmid DNA
  • stable compared to protein or RNA
  • cheap
  • low-risk
45
Q

DNA vaccine scheme (6)

A
  • origin of replication
  • eukaryotic promoter
  • antigen genes
  • cytokine and co-stimulatory molecule genes
  • terminator
  • selectable marker to help with cloning
46
Q

DNA vaccine mechanism (4)

A
  1. delivered via injection (DNA in saline) into muscle cells
  2. DNA gets endocytosed
  3. DNA goes into the nucleus where it is transcribed
  4. mRNA goes to cytosol, can be found on cell surface, or can be secreted from the cell
47
Q

what kind of immune responses are DNA vaccines good at eliciting (2)

A
  • Ab immune response
  • CMI immune response
48
Q

why can bacterial DNA be used as an adjuvant (3)

A
  • bacterial DNA has CpG dinucleotides
  • 1/16 dinucleotides in bacteria are CpGs (not methylated)
  • CpGs are rare and methylated in vertebrates
49
Q

what roles does bacterial DNA play as an adjuvant (3)

A
  • bacterial DNA CpGs are strong activators of B cells
  • strong activators of monocytes
  • can induce Th1 response
50
Q

why are DNA bacterial plasmids considered low-risk (2)

A
  • non-infectious
  • do not replicate in humans or animals
51
Q

how can DNA vaccines be improved (3)

A
  • methods to improve gene expression
  • delivery systems to antigen presenting cells
  • target dendritic cell delivery
52
Q

improving DNA vaccines: methods to improve gene expression (2)

A
  • better promoters
  • correcting for codon bias
53
Q

improving DNA vaccines: delivery systems to APCs (2)

A
  • Langerhans cells (type of DC) residues just under skin
  • gene guns, microneedles, tattoo guns to target these cells
54
Q

improving DNA vaccines: targeting DC delivery

A
  • fusing a gene encoding an antibody to a DC receptor to the antigen
55
Q

DNA vaccine delivery: gene gun (2)

A
  • carries multiple genes by coating them onto microcarriers
  • microcarriers are dense enough to enter target tissues (APCs)
56
Q

gene gun: microcarriers (4)

A
  • spheres
  • nontoxic
  • subcellular-sized
  • often positively charged gold
57
Q

mRNA vaccines: safety (2)

A
  • mRNA is non-infectious and non-integrating; no potential risk of infection or insertional mutagenesis
  • mRNA is degraded by normal cell processes
58
Q

what are some disadvantages to mRNA vaccines (2)

(class slides)

A
  • can be unstable
  • can be difficult to translate
59
Q

how can the disadvantages of mRNA vaccines be overcome

A
  • various modifications can be made to the mRNA to make it more stable and highly translatable
60
Q

mRNA vaccines: how can efficient in vivo delivery be achieved

A
  • formulating mRNA into carrier molecules
  • allows for rapid uptake and expression in cytoplasm
61
Q

mRNA vaccines: production advantages (4)

(class slides)

A
  • rapid
  • inexpensive
  • scalable manufacturing
  • high yields of in vitro transcription reactions
62
Q

mRNA vaccines: production steps (5)

A
  1. cloning to produce cDNA
  2. transcription of cDNA into mRNA
  3. capping and co-transcriptional capping of mRNA
  4. purification to produce purified and capped mRNA
  5. storage as a mRNA-LNP
63
Q

mRNA vaccines: how is mRNA made more stable (5)

A
  • 5’ cap is added to mRNA
  • optimized codon usage
  • enrichment of G+C content
  • modification of vaccine immunogen coding region
  • storage in a lipid carrier
64
Q

why doesn’t human mRNA elicit an immune reaction

A
  • many modifications naturally found in human RNA reduce it immunostimulatory potential
65
Q

what kinds of modifications are naturally made to human RNA to reduce immunostimulatory potential (3)

A
  • reduced synthesis of antisense RNA
  • altering interaction with RNA secondary structure
  • altering interaction with single-stranded RNA immune receptors
66
Q

mRNA vaccines: what kind of modifications can be made to the immunogen coding region to increase stabilization

A
  • m1Ψ
67
Q

mRNA vaccines: m1Ψ modification (2)

A
  • alteration to uridine of endogenous mRNA produces m1Ψ
  • done through isomerization of C-glycoside; a steric “bump”
68
Q

DNA and RNA vaccines: advantages (4)

(outside chart)

A
  • simple, scalable manufacturing
  • rapid deployment
  • safety (no change of infection compared to live/attenuated pathogen vaccines)
  • better cellular and humoral immune response (compared to only subunit vaccines)
69
Q

DNA vaccines: advanatges (4)

(outside chart)

A
  • persistence
  • prolonged expression
  • stable under normal conditions
  • ease of storage
70
Q

RNA vaccines: advantages (5)

(otside chart)

A
  • short half-life allows controlled expression kinetics
  • amplification during manufacturing
  • no need to enter nucleus
  • no change of genomic integration
  • cell-free, in vitro synthesis
71
Q

DNA and RNA vaccines: disadvantages

(outside chart)

A
  • immunogenicity below expectations in human clinical trials
72
Q

DNA vaccines: disadvantages (2)

(outside chart)

A
  • theoretical possibility of adverse events from genomic integration
  • nuclear delivery required
73
Q

RNA vaccines: disadvantages (2)

(outside chart)

A
  • additional steps required in productions
  • susceptible to degradation ex vivo and in vivo

MICB 308 (22 decks)

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