Neonatal immunity Flashcards
Complete development of the immune system requires…?
Antigen stimulation
What is essential for all veterinary species in the first few weeks of life?
Passive transfer of immunity from mother to newborn
What is the first foetal lymphoid structure?
Thymus
What develops at the same time as antibody production?
Cell mediated immunity
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
- Blood lymphocytes
- Bone marrow, spleen
- Lymph nodes
- Complement
- Peyer’s patches
What is the role of maternal hormones?
At birth they promote anti-inflammatory phenotype
- short lived
What are the 2 common infections that can occur during pregnancy?
- BVDV = bovine viral diarrhoea virus
- Neospora caninum
How do they effects of Neospora caninum change throughout the 3 pregnancy trimesters?
1st - absorption of mummified foetus
2nd - abortion
3rd - live calf with congenital infection
What are the two strains of BVD?
Non-cytopathic - doesn’t kill cells
Cytopathic - kills cells
Neonatal immunity is always what type of response?
Primary
Compare the Transfer of immunity to offspring in:
- dogs/cats
- ruminants, pigs, horses
- 5% placental, 95% colostral
- 100% colostral
How does colostrum provide immunity?
Active transfer of Igs from blood to mammary gland under hormonal influence
What is the main colostrum antibody?
IgG
As colostrum changes to milk get reduced IgG content, proportionally more … ?
IgA
What are important considerations surrounding the transfer of colostrum?
- 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)
As well as antibodies, colostrum also contains?
Growth factors (cytokines) and other hormones
Compare how maternal antibodies are absorbed in:
- horse and pig
vs
- ruminants
- IgG and IgM selectively absorbed to blood; IgA stays in intestine
- All Igs go into blood
How are calves adapted for readily colostrum intake?
- have an oesophageal groove at birth (for 20 days)
- this diverts colostrum and milk straight into the abomasum, avoiding the rumen and omasum
When do peak levels of Igs happen?
12-24 hours after birth
Why do very serious infections result in Ig deficit situations?
Because:
- IgG prevents septicaemia
- IgA prevents enteric disease
Failure of passive transfer can occur due to failure of?
- Production
- Ingestion
- Absorption
What is measured to determine if there has been a failure of passive transfer?
Serum IgG
How is FPT treated?
- Additional colostrum, only up to 15 hours old
- IV plasma when over 15 hours
Why do Non-suckled calves make antibodies sooner than suckled calves?
Maternally derived antibodies inhibit antibody production
What needs to be considered when vaccinating young animals?
- 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)
