Immunology Introduction

Question 1

What characterises most successful pathogens?

Answer 1

pecialists overcoming host immunity, high virulence

Question 2

What mechanisms allow evasion of host immunity?

Answer 2

Antigenic variation, immunomodulation, intracellular survival, host molecule mimicry, phagocytosis subversion…

Question 3

What is antigenic variation?

Answer 3

Allows pathogen to alter surface molecules to evade recognition by host immune system.

Question 4

What’s an example for plants?

Answer 4

Puccinia graminis (wheat stem rust fungus).

Question 5

How do they exhibit antigenic variation?

Answer 5

Gene-for-gene interaction with production of antivirulence proteins recognised by resistance proteins in host plants.

Question 6

What is the mechanism of Avr and R proteins?

Answer 6

When they match, immune response is triggered thus pathogenic resistance.

Question 7

How does P. Graminis respond?

Answer 7

Genetic recombination with emergence of new pathogenic variants with altered Avr proteins evading recognition.

Question 8

What is immunomodulation?

Answer 8

Production of molecules suppressing host immune response to their advantage

Question 9

What is an example?

Answer 9

Secretion of immunosuppressive cytokines, interfering with signalling pathways involved in immune activation.

Question 10

What is a case study example?

Answer 10

Coral reefs and their microbiomes.

Question 11

Why are they relevant to this?

Answer 11

Within the holobiont (coral host, zooxanthellae, and microbial communities), regulates corals immune responses.

Question 12

How does the microbiome boost the immune response?

Answer 12

Enhance pathogen resistance through production of coral probiotcs that inhibit coral pathogen growth, or by activation of PRR, triggering immune signalling pathways enhancing coral ability to defend against pathogens.

Question 13

How do pathogens overcome this?

Answer 13

Production of virulence factors or immunomodulatory molecules suppressing corals immune defences.

Question 14

What are the classes of defense?

Answer 14

Barrier, chemical and cellular.

Question 15

What are the classes of animal defence?

Answer 15

Innate immunity, adaptive immunity, humoral immunity, and cellular immunity.

Question 16

How can classes of plant defence be classified?

Answer 16

Based on mechanism and timing, so physical, chemical, SAR, indirect defenses…

Question 17

What is the mechanism of physical defences?

Answer 17

Structures like thorns, trichomes, spines, outer layers(cuticle), deterring herbivores and pathogens.

Question 18

How do thorns facilitate deterrance?

Answer 18

Secretion of secondary metabolites like terpenoids, alkaloids, phenolics, and flavonoids.

Question 19

How do terpenoids function in feeding deterrance?

Answer 19

Evoke aversive responses in herbivores through interaction with taste receptors or olfactory neurons, triggering responses discouraging further behaviour.

Question 20

What is the timing of physical defence?

Answer 20

Production/release of compounds deterring herbivores, pathogens, and competitors, like alkaloids, terpenoids, phenolics, and glycosides.

Question 21

What is the mechanism of chemical defence?

Answer 21

Production/release of toxic/detterant compounds for herbivores, like alkaloids, terpenoids, phenolics, and glycosides.

Question 22

What are alkaloids?

Answer 22

Nitrogen containing compounds in plants, including nicotine and caffeine.

Question 23

How do they deter predators?

Answer 23

Acting on nervous system inducing paralysis and convulsions, or deterrance of feeding behaviour.

Question 24

What happens when primary barriers are compromised, using tetanus and gas gangrene as examples?

Answer 24

Tetanus is introduced through wounds, proliferating in anaerobic environments like necrotic tissues, producing tetanospasmin and tetanolysin which invade nervous system, inhibiting neurotransmission at synapses, resulting in loss of control and sustained muscle contractions.

Question 25

What is tetanospasmin?

Answer 25

Blocks release of neurotranmistters in CNS

Question 26

What is Tetanolysin?

Answer 26

A toxcin damaging RBC and other host cells, contributing to tissue destruction.

Question 27

How do they invade the CNS?

Answer 27

Travel across nerve fibres, disrupting specifically release of Gamma-Aminobutyric Acid, which regulates muscle activity.

Question 28

How can barrier defences be strengthened in response to attack?

Answer 28

Localised Increased cell turnover, tight junction reinforcement, mucous production, antimicrobial peptide release or systemic responses through inflammatory signalling and immune activation

Question 29

What does enhanced mucous production do?

Answer 29

Secretion of a gel by goblet cells, thickening protective layers and trapping pathogens before breaching epithelial barriers.

Question 30

Why is inflammatory signalling important?

Answer 30

Mediators like cytokines and chemokines are released, signalling neighbouring cells to reinforce barrier integrity through immune cell recruitment to site of infection.

Question 31

What are physical barrier examples in invertebrates?

Answer 31

exoskeletons, External mucous, respiratory mucous…

Question 32

What are examples of physiological barriers?

Answer 32

Lysozyme, digestive enzymes, acidic pH of stomach, body temperature/fever, commensal bacteria on skin and intestine.

Question 33

What is the function of Lysozymes?

Answer 33

Antimicrobial activity through catalysis of hydrolysis of peptidoglycans which is an important component of bacterial cell walls.

Question 34

What is the function of Lysozymes?

Answer 34

Antimicrobial activity through catalysis of hydrolysis of peptidoglycans which is an important component of bacterial cell walls.

Question 35

How does pH act as a physiological barrier?

Answer 35

Through maintenance of an acidic environment of pH betweeen 1.5-3.5 through HCL secretion by parietal cells, providing hostile environment for microorganisms.

Question 36

What physical defences are found within the cell wall?

Answer 36

Lignification, and hydroxyproline-rich gylcoproteins.