Neonatal immunity

Question 1

Complete development of the immune system requires…?

Answer 1

Antigen stimulation

Question 2

What is essential for all veterinary species in the first few weeks of life?

Answer 2

Passive transfer of immunity from mother to newborn

Question 3

What is the first foetal lymphoid structure?

Answer 3

Thymus

Question 4

What develops at the same time as antibody production?

Answer 4

Cell mediated immunity

Question 5

Following development of the thymus put the following in order of their foetal development:

• Peyer’s patches
• Lymph nodes
• Bone marrow, spleen
• Complement
• Blood lymphocytes

Answer 5

• Blood lymphocytes
• Bone marrow, spleen
• Lymph nodes
• Complement
• Peyer’s patches

Question 6

What is the role of maternal hormones?

Answer 6

At birth they promote anti-inflammatory phenotype

- short lived

Question 7

What are the 2 common infections that can occur during pregnancy?

Answer 7

• BVDV = bovine viral diarrhoea virus

- Neospora caninum

Question 8

How do they effects of Neospora caninum change throughout the 3 pregnancy trimesters?

Answer 8

1st - absorption of mummified foetus
2nd - abortion
3rd - live calf with congenital infection

Question 9

What are the two strains of BVD?

Answer 9

Non-cytopathic - doesn’t kill cells

Cytopathic - kills cells

Question 10

Neonatal immunity is always what type of response?

Answer 10

Primary

Question 11

Compare the Transfer of immunity to offspring in:

• dogs/cats
• ruminants, pigs, horses

Answer 11

• 5% placental, 95% colostral

- 100% colostral

Question 12

How does colostrum provide immunity?

Answer 12

Active transfer of Igs from blood to mammary gland under hormonal influence

Question 13

What is the main colostrum antibody?

Answer 13

IgG

Question 14

As colostrum changes to milk get reduced IgG content, proportionally more … ?

Answer 14

IgA

Question 15

What are important considerations surrounding the transfer of colostrum?

Answer 15

• Essential it happens in the first few hours of life
• Colostrum ingested and passes into GI tract where enzyme levels are low/blocked so that proteins can reach small intestine
• Newborns have a specialised Fc receptor on intestinal epithelial (only for up to 24 hours)
• In GI tract, Igs are bound, actively pinocytosed and quickly reach lymphatics and circulation
• So, in first few hours of life, newborn receives large amount of Igs from mother – rapidly seen in plasma Ig levels as maternally derived antibodies (MDA)

Question 16

As well as antibodies, colostrum also contains?

Answer 16

Growth factors (cytokines) and other hormones

Question 17

Compare how maternal antibodies are absorbed in:
- horse and pig
vs
- ruminants

Answer 17

• IgG and IgM selectively absorbed to blood; IgA stays in intestine
• All Igs go into blood

Question 18

How are calves adapted for readily colostrum intake?

Answer 18

• have an oesophageal groove at birth (for 20 days)

- this diverts colostrum and milk straight into the abomasum, avoiding the rumen and omasum

Question 19

When do peak levels of Igs happen?

Answer 19

12-24 hours after birth

Question 20

Why do very serious infections result in Ig deficit situations?

Answer 20

Because:

• IgG prevents septicaemia
• IgA prevents enteric disease

Question 21

Failure of passive transfer can occur due to failure of?

Answer 21

• Production
• Ingestion
• Absorption

Question 22

What is measured to determine if there has been a failure of passive transfer?

Answer 22

Serum IgG

Question 23

How is FPT treated?

Answer 23

• Additional colostrum, only up to 15 hours old

- IV plasma when over 15 hours

Question 24

Why do Non-suckled calves make antibodies sooner than suckled calves?

Answer 24

Maternally derived antibodies inhibit antibody production

Question 25

What needs to be considered when vaccinating young animals?

Answer 25

- MDA inhibit neonatal Ig synthesis - Prevent successful vaccination in young animals - Need to wait until there are low levels of passive antibody (10-12 weeks)