Neonatal Immunity Flashcards
How does the foetal immunity and organs develop?
Thymus appears first
Followed by secondary lymphoid organs
Cell mediated immunity develops at same time as Ab production
Why are phagocytes not developed in neonates?
Circulating levels of macrophages and neutrophils are normal but not functional
Maternal hormones promote anti-inflammatory phenotype, so could imprint non-responsive effects
Lower complement levels which are needed to facilitate phagocytosis
What are two common intrauterine infections during pregnancy?
Neospora caninum
BVDV (bovine viral diarrhoea virus)
What does Neospora caninum cause in the first second and third trimester?
1st trimester- absorption of mummified foetus
2nd trimester- abortion
3rd trimester- foetus immunocompetent- congenital infection
What are the two strains of BVDV and what do the different strains cause?
Non-cytopathic
Cytopathic
If non-cytopathic caught before 125 days there is tolerance of persistent infection
If non-cytopathic after 125 days- normal calf
If cytopathic before 100- abortion, reabsorption
If cytopathic 100-150- malformations
normal 150-200
Why does a neonate need passive transfer of immunity?
Neonatal immunity is always a primary response
Needs maternal assistance- MDA, some lymphocytes in colostrum
How do animals transfer immunity to offspring?
Placental transfer in primates (IgG only)
5% placental, 95% in dogs and cats
100% colostral in ruminants, pigs and horses
When is colostrum produced, how is it produced and what antibodies does in contain?
Produced in last 5 weeks of pregnancy
Process- active transfer of Its from blood to mammary gland under hormonal influence (oestrogen and progesterone)
Contains- main antibody is IgG, as is changes to milk more IgA. Also contains growth factors and other hormones
All IgG, most IgM and half IgA deprived from serum
How do the antibodies of colostrum reach the neonate?
Colostrum ingested
Enzyme levels are low/blocked so proteins reach small intestine
Newborns have Fc receptor (briefly)
Igs are bound, actively pinocytosed to reach lymphatics and circulation
How do different species absorb Igs differently?
Horse and Pig- IgG and IgM selectively absorbed into blood, IgA stays in intestine
Ruminants- all Igs go to blood
How can failure of passive transfer of immunity fail?
Production- premature lactation
Ingestion- multiple births, damaged teats
Absorption- 25% of foals
Why is failure of passive transfer potentially very dangerous?
IgG prevents septicaemia
IgA prevents enteric disease
How can failure or passive transfer be diagnosed?
Hydrometer/colostrometer- measures specific gravity, correlated with protein/IgG content
How can failure of passive transfer be treated?
Additional colostrum- before 15 hours
After 15 hours- No oral absorption, IV plasma, commercially available with high specific antibody titres
Why do non-suckled calves make antibodies sooner then suckled calves?
MNA prevent antibody production
