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Immuno > General characteristics of Antigens > Flashcards

General characteristics of Antigens Flashcards

1
Q

Entry of antigens into the body

A

By the skin and mucus membranes- tissue damage

Cytokines and leucocytes are at the site of injury

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2
Q

ASF= African Swine Fever, and why is it so serious?

A

50 proteins on the surface

The neutralization part is hidden- cannot be found by the immune system- so no AB’s are produced against it

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3
Q

3 Characteristics of the antigen

A

Immunogenicity
Tolerogenicity
Antigenicity

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4
Q

Immunogenicity

A

Ability of a molecule to elicit an immune response– effector cells and antibodies

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5
Q

Tolerogenicity

A

Ability of antigen to prevent immune response

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6
Q

Antigenicity

A

Ability of molecule to be identified by Atg recognising immune cells

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7
Q

What are the 2 most important components of the antigen?

A

Carrier

Epitope (where the ab binds)

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8
Q

Specificity of the antibodies

A

Specific for the carrier
Specific for the epitope
Specific for both the carrier and the epitope

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9
Q

Cross-reactivity

A

When there is similarity between the epitops- but not the very same
Used in vaccinations e.g turkey herpes virus as vaccine for Marek’s disease
TB- M. Bovis and M. Avium

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10
Q

Factors Influencing Immunogenicity

A

Immunogen
Biological System
Epitope
Method of admin

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11
Q

Factors Influencing Immunogenicity: Immunogen

A
  1. Foreignness- how many non-self epitopes- usually correlates with size! Also, remember D-aa is not in mammals
  2. Size- larger, more epitopes, may be spaced further apart
  3. Chemical: Proteins: tertiary are the strongest
    Polysaccharide: rare- glycoprotein
    NA: rare
    Lipids: NONE
  4. Degradability
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12
Q

Factors Influencing Immunogenicity: Epitope

A
  1. Composition- aa sequence, the longer and more complex the better e.g Gly polymer not immunogenic
  2. Structure
    linear- necessary for T-cells
    conformation- B-cell
  3. Number
    many of the same or of different epitopes
    accessibility e.g hidden epitopes
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13
Q

Factors Determining Antigenicity

A

Biological factors
Route of admin
Quantity of antigen
Antigen competition- polyvalent vaccines
Adjuvants- immunostimulation- depot effect
Antigen type- T dependent/independent

+cultures can be infected by non-pathogenic viruses

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14
Q

Factors determining antigenicity: Biological factors

A 
Here there are huge individual differences 
Genetic factors- MHC, TCR, BCR
Age- too young, too old 
Condition
Keeping 
Feeding
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15
Q

Factors Influencing Immunogenicity: Route of admin

A

Parenteral vs enteral

Oral tolerance vs oral vaccination

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16
Q

Factors Influencing Immunogenicity: Quantity of antigen

A

No effect or tolerated

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17
Q

Factors influencing the effect of the Atg: Booster effect

A

2nd dose of the vaccine generates a stronger immune response than the first, this is due to the immunological memory and B and T cells i.e the acquired immune response

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18
Q

Factors Influencing Immunogenicity: Adjuvant

A

Any substance than when given with an antigen, it enhances the immune response to that antigen.
Negative side effects:
-prolong the presence of the antigen
-inflammation
-activate innate immune system- complement cascade and phagocytosis

19
Q

What are the 3 possible ways of recognition

A
  1. Pathogen/Non-self:
    - markers and metabolic products of microorganisms
    - PAMP
  2. Missing self
    - self markers on the surface of normal cells, which can block the immune response
  3. Altered self
    - markers not resembling healthy self-markers
20
Q

Visible self

A

Antigens of the body that are tolerated

21
Q

Invisible self

A

Antigens that are not tolerated but are ignored under normal circumstances

22
Q

Visible non-self

A

This is what the immune system usually reacts with

23
Q

Invisible non-self

A

Non-self antigens that are not reacted with

24
Q

2 main functions of the immune system

A

Attacks foreign (non-self)
Tolerates self
(the body is self and the rest of the universe is foreign)

25
Q

What are the 2 things necessary for an immune response to occur?

A

Pathogen

Danger

26
Q

Stranger model of the immune response

A

Pathogen– PAMP3 and these bind to the PRR on the dendritic cell
Dendritic cell maturation- a peptide MHC complex seems to appear
CD60 and/or CD86 co-stimulatory molecule
Then this dendritic cell migrates to the lymph nodes and the TCR of a T-cell binds to the MHC

27
Q

Danger model of the immune response

A

Necrotic cell death
Stimulates the release of DAMP’s and these then bind to the DAMP receptor of the Dendritic cell

From here it is the same as the stranger model

DAMP= damage associated molecular pattern

28
Q

What is the Pathogen-Associated Molecular Pattern (PAMP)

A

Exogenous molecular patterns that can activate the non-specific immune response
It’s receptor consists of specific proteins on the surface that react with the antigens

29
Q

PAMP and gram (+)

A

**Lipotechoic acid
Lipoprotein
Peptidoglycan

30
Q

PAMP and gram (-)

A

**LIPOPOLYSACCHARIDE (how they recognise it is foreign)
Lipid A
Porin
Peptidoglycan (much thinner than gram (+))

31
Q

PAMP and acid-fast

A

**Mycolic acid
Porin
Galactan
Peptidoglycan (thin)

32
Q

Some other examples of PAMP

A 
LPS of gram (-) is NB
Lipoproteins 
Peptidoglycan layer 
Mannose, dextrose 
Flagellin
Haemaglutinin
33
Q

DAMP (damage associated molecular pattern) can be

A

Extracellular and intracellular

34
Q

Some examples of DAMPs

A 
Hyaluronic acid is NB!!!
Heat shock protein
DNA
Fibrinogen
Cholesterol
35
Q

What are the 2 basic types of receptors

A
  1. Pattern Recognition Receptor (PRR)
    - can bind to PAMP or DAMP
    - can be on the surface or in the cytoplasm
  2. Opsonin Recognition Receptor (ORR)
    - opsonins
36
Q

The types of ORRs

A

Fc receptors
Complement receptors
Lectin receptors (mannose)

37
Q

The types of PRRs

A 
Scavenger receptor (SR)
Mannose receptor (MR)
LPS receptor (CD14)
**Toll-like receptor (TLR)
NOD-like receptor (NOD1, NOD2)
Retinoic acid inducible gene (RIG)-like receptor
38
Q

LPS receptor (CD14) ligand and action

A

Ligand: LPS
Action: removal of microbes and induction of inflamm cytokines (for recognition)

39
Q

Toll-like receptor (TLR) ligand and action

A

Ligand: Pathogen patterns on the cell surface or the endosome
Action: Signal to adaptive immune system

40
Q

NOD-like receptor (NOD1, NOD2) ligand and action

A

The peptidoglycan layer on gram (-) and acts in the CYTOSOL
Action: Inflamm IL-6, IL-12, TNF
apoptosis- IL-1

41
Q

Scavenger Receptor (SCAR)

A

Scavenger= animal/organism that feeds on organic dead matter– FUNGI are NB
Are macrophage receptors that recognise low density lipoprotein (LDL) elements of the bacterial cell wall and eukaryotic cell membrane

42
Q

Mannose Receptor family, location and action

A

Location:
Macrophages
Immature DC
Endothelial, epthelial and Kuppfer cells

Action:
Recognition of carbohydrates of pathogens

43
Q

Nod-like receptors (NLR) more specifically

A

NOD: Nucleotid-binding oligomerization domain

React to microbial intracellular PAMPs

NOD1: peptidoglycans—> IL-1, IL-8
NOD2: muramyl dipeptide—> defensin
NOD3: viral NA, silica

44
Q

RIG-Like receptor

A

RIG: Retinol acid Inducible Gene

Action:

  • Viral dsRNA detection
  • Capsase activation
  • Trigger the production of IFN-1

Immuno (12 decks)

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