1. Defensive barriers

Question 1

What are horizontal routes of transmission?

Answer 1

Direct contact
Aerosol
Oro-faecal
Vector borne

Question 2

What are vertical routes of transmission?

Answer 2

Mother to embryo

- direct contact

Question 3

Example of a direct contact disease

Answer 3

Greasy pig disease

• staphylococcus bacteria
• staphylococcus hyicus

Question 4

Example of a aerosol transmission disease

Answer 4

Kennel cough

Question 5

Example of a oro-faecal transmission disease

Answer 5

haemorrhagic enteritis

- Clostridium perfringens

Question 6

Example of a vector transmitted disease

Answer 6

Pathogen uses an arthropod host to spread from animal to animal when it bites

• sandfly (e.g., Leishmaniosis)
• tick (e.g., Lyme disease)

Question 7

Example of a transplacental transmission disease

Answer 7

Pathogen crosses the placental barrier to infect foetus e.g., Bovine virus diarrhoea (BVD)

Question 8

What are commensal flora “friendly bacteria”?

Answer 8

• prevent pathogenic organisms from colonising
• provide competition
• may trigger a low level of functional immunity

Question 9

What effect do antibiotics have on commensal flora?

Answer 9

Remove normal flora which can cause colonisation of pathogenic organisms

Question 10

What do keratinocytes replicate to become?

Answer 10

Stratified squamous keratinised epithelium

Question 11

What is the role of melanocytes?

Answer 11

Offer protection from UV damage

Question 12

What are Langerhans cells?

Answer 12

Immune sentinels

• detect an antigen and take up the microbe
• migrate to lymph node and the lymph node where the immune cells reside and can generate an immune response

Question 13

What is sebum?

Answer 13

Water repellant
Contains fatty acids (pH 5.5)
Anti-microbial components

Question 14

How do keratinocytes detect and respond to infection?

Answer 14

When a microbe binds to a keratinocyte they express molecules on the cell surface that recognise microbes

Question 15

What is the significance of toll like receptors?

Answer 15

Expressed on keratinocytes

• when microbes bind to these receptors a signalling cascade is triggered that can lead to the production of various soluble factors
• have anti-microbial properties

Question 16

What are AMPs: Beta-defensins?

Answer 16

• small cationic peptides
• broad spectrum anti-microbial properties
• disruption of microbial membranes and/or interference with intracellular functions

Question 17

What are the Beta-defensins expressed in humans?

Answer 17

• HBD1 constitutively expressed by keratinocytes

- HBD 2-4 Inducible in keratinocytes in response to infection

Question 18

What are the Beta-defensins expressed in dogs?

Answer 18

3 genes have been identified

Question 19

What does the triggering of inflammation by keratinocytes produce?

Answer 19

Cytokines = immunological hormones
Chemokines = cell migration factors

Question 20

What is mucous made up of?

Answer 20

Water + electrolytes 
Glycoproteins + lipids 
Antimicrobial compounds 
- transferrin 
- lactoferrin 
- lysozyme 
Antibodies (IgA)
Antioxidants 
- superoxide dismutase 
- catalase 
- glutathione peroxidase

Question 21

What is the mucocillary escalator?

Answer 21

Continual escalator of cilia that prevents microbes binding, adhering and colonising
- once infected host becomes immunocomprimised which can damage the escalator

Question 22

What are alveolar macrophages?

Answer 22

Single celled - involved in phagocytosis

• main line of defence against inhaled microbial pathogens and inanimate particles
• derived from blood monocytes and interstitial macrophages
• short lifespan in alveoli

Question 23

What are the phases of phagocytosis?

Answer 23

Binding 
Attachment phase 
Phagosome forming 
Phagolysosome forms 
Microbe destroyed

Question 24

What are the physical and biochemical barriers in the oral cavity and oesophagus?

Answer 24

Physical = stratified squamous epithelium 
Biochemical = lysozyme in saliva

Question 25

What is the defence mechanism in the small intestine?

Answer 25

Cryptidins (similar to defensins)

• toxic to bacteria
• synthesised by Paneth cells present in the intestinal crypts

Question 26

What is the defence mechanism in the GIT?

Answer 26

Gut associated lymphoid tissue - factor where you make immune responses (Peyers patches)
- specific mucosal protective antibody (IgA)