C3

Question 1

Define virulence factor

Answer 1

Molecules expressed & secreted that enable them to colonise the host, evade & inhibit the immune response of host

Question 2

Factor that enhances transmission

Answer 2

• Multiple sources & high endemicity
• High conc released into environment media
• High carriage rate
• Proliferate & adapt to different host
• Seasonality & climatic effects
• Antibiotic resistance

Question 3

Define virulence properties

Answer 3

Structure or chemical constituents that contribute to pathophysiology

Question 4

Example of virulence properties

Answer 4

• Outer cell membrane of Gram -ve
• Exotoxin
• Pili
• Invasins

Question 5

Host factor in pathogen transmission

Answer 5

• Age
• Immune status
• Pregnancy
• Genentic background
• Nutritional status

Question 6

What is adhesin

Answer 6

Found on cell wall of bacteria that bind to specific receptor molecule on surface of host cell

Question 7

Example of adhesin

Answer 7

• Fimbriae
• Capsule
• Biofilm
• Fibronectin binding protein (FBP)

Question 8

Explain the relationship of surface structure & virulence

Answer 8

• Bacterial surface antigen altered by mutation
• Progeny are no longer recognised by immune response
• Result in renewed virulence

Question 9

Colonisation factor

Answer 9

• Ability to use motility to contact & disseminate host
• Ability to adhere & resist physical removal
• Ability to invade host cell
• Ability to compete for iron & other nutrients
• Ability to resist innate immune defense
• Ability to evade adaptive immune defence

Question 10

Virulence factor in bacteria encoded on

Answer 10

• Chromosomal DNA
• Bacteriophage DNA
• Plasmid
• Transposons

Question 11

How virulence factor transmit

Answer 11

• Bacteria infect by bacteriophages
• Integrate its genome into bacterial chromosome
• Serve as basis of toxin production

Question 12

Define antigenic drift & antigen shift

Answer 12

Antigenic drift
- Result of point mutation causing slight mutation in spike protein hemagglutinin (H) & neuroamidase (N)

Antigenic shift
- Major change in spike protein due to gene reassortment
- 2 different influenza infect same host

Question 13

Antigenic variation result in

Answer 13

Continual emergence of new strain that immune system not recognise

Question 14

Explain tumor necrosis factor

Answer 14

• Release by Gram -ve bacteria
• Involved inflammation & fever
• Bind with blood capillaries to increase permeability
• Cause edema or swelling

Question 15

Class & example of exoenzyme

Answer 15

• Glycohydrolases: Hyaluronidase
• Nucleases: DNAse
• Phospholipases: Phospholipase
• Protease: Collagenase

Question 16

Function of exoenzyme

Answer 16

Facilitate invasion or support its own growth & defend against immune system

Question 17

Function of Hyaluronidase, DNAse, phospholipase & collagenase

Answer 17

Hyaluronidase & Collagenase
- Allow pathogen to pass through tissue layer & spread in the body

DNAse
- Degrade extracellular DNA to escape & spread through tissue

Phospholipase
- Degrade cell membrane
- Lyse target cell (RBC, WBC, tissue)

Question 18

Lipid A trigger

Answer 18

Inflammatory response

Question 19

What happen when concentration of endotoxin is high

Answer 19

• Cause excessive inflammatory response
• Result in low blood pressure, multi organ failure

Question 20

How to inactivate endotoxin & exotoxin

Answer 20

Endotoxin
- Heat stable
- 121C & 45 mins to inactivate

Exotoxins
- Heat labile
- 41C

Question 21

Explain exotoxin

Answer 21

• Target specific receptors on specific cell
• Damage cell through unique molecular mechanisms

Question 22

Characteristics of endotoxin & exotoxin

Answer 22

Endotoxin
- Gram -ve
- Lipid A
- General effects
- Heat stable
- LD50: High

Exotoxin
- Gram +ve & -ve
- Protein
- Specific
- Heat labile
- LD50: Low