Neonate Immunity

Question 1

What is ontogeny?

Answer 1

The development of an individual organism or anatomical or behavioral feature from the earliest stage to maturity

Question 2

What is the first lymphoid organ to develop?

Answer 2

thymus

Question 3

What is the difference between short and long gestation in regards to immune system development?

Answer 3

Short gestation = primary lymphoid organs develop after birth

Long gestation = full development of the immune system at birth

Question 4

Why is the immune system still vulnerable at birth even when fully developed?

Answer 4

The immune system is naive for several reasons including the fact that they are not exposed to antigens in utero unless there was an infection.

Question 5

What drives the development of a good immune response by neonates?

Answer 5

Antigen driven by environmental exposure

Question 6

What is the average time for fetal thymus development?

Answer 6

About 40 days post-conception

Question 7

How long is the gestation period for foals, calves, and pigs?

Answer 7

foals: 340 days
calf: 280 days
pigs: 115 days

Question 8

Why are neonates vulnerable to infection?

Answer 8

Innate immunity suppressed by fetal cortisol released during birth results in suppressed phagocytic function.

Adaptive immunity is naive and dependent on exposure to antigens.

Neonatal immune responses are biased toward Th2 immune responses and suppress Th1 immune responses.

Question 9

What is the advantage of Th1 immune suppression in neonates?

Answer 9

IFN-y (produced by Th1 response)

CTLs could recognize foreign MHC I expressed by the fetus

Question 10

What is the disadvantage of Th1 immune suppression in neonates?

Answer 10

Increased susceptibility to intracellular bacteria

Question 11

What is passive immunity?

Answer 11

The transfer of active humoral immunity in the form of ready-made antibodies, from one individual to another

Question 12

What maternal antibody is transferred across placental tissues?

Answer 12

IgG

Question 13

What animals have free transfer of IgG across the placenta?

Answer 13

rodents, primates

Question 14

What animals have no transfer of IgG across the placenta?

Answer 14

ruminants, horses, donkeys, pigs

Question 15

What maternal antibody is transferred to the chicken egg?

Answer 15

IgY

Question 16

What animals have slight transfer of maternal IgG? What percentage is it?

Answer 16

dogs and cats

5-10%

Question 17

What animal has a hemoendothelial placentation and how many tissue layers?

Answer 17

rodents; 1

Question 18

What animal has a hemochorial placentation and how many tissue layers?

Answer 18

primates; 3

Question 19

What animal has a endotheliochorial placentation and how many tissue layers?

Answer 19

dogs and cats; 4

Question 20

What animal has a syndesmochorial placentation and how many tissue layers?

Answer 20

ruminants; 5

Question 21

What animal has an epitheliochorial placentation and how many tissue layers?

Answer 21

horse, donkeys, and pigs; 6

Question 22

How is a neonate protected while the immune system becomes fully competent?

Answer 22

passive transfer- antibody (and cells) provided by an external source

Question 23

How is passive immunity acquired?

Answer 23

maternal antibody via colostrum or placenta

administration of plasma containing antibodies (can be an injection)

Question 24

What would you recommend for horse/cattle breeders do before foaling/calving?

Answer 24

vaccination

Question 25

When are peak serum immunoglobulin levels normally reached?

Answer 25

12 to 24 hours

Question 26

When do foals and calves begin to produce antibodies and when are they detectable?

Answer 26

Immediately upon exposure to antigens after birth

Detectable within 1-2 weeks of life and reach protective levels by 2 months

Question 27

What is colostrum?

Answer 27

Mammary gland secretions occur late in pregnancy due to estrogens and progesterone

Question 28

What is the primary antibody in colostrum of most domestic species?

Answer 28

IgG (65-90%)

Small amounts of IgA and IgM

Question 29

What is the primary antibody in colostrum in primates?

Answer 29

IgA

Question 30

What is the difference in composition of milk and colostrum?

Answer 30

Majority of Ig in milk in produced by lymphoid tissue and not transferred from serum like colostrum.

Question 31

What is the predominant antibody in milk?

Answer 31

Ruminants- IgG1

Non-ruminants- IgA

Question 32

What provides protection from enteritis in neonates?

Answer 32

Milk Ig (IgA/IgG1)

Question 33

What provides systemic immunity in neonates?

Answer 33

colostral IgG

Question 34

What receptor does IgG bind to on the intestinal epithelial cells of neonates?

Answer 34

Fc receptor (FcRn)

Question 35

How much colostrum do calves and foals ingest on average?

Answer 35

2 Liters

Question 36

What is gut closure?

Answer 36

After 24 hours, a new layer of enterocytes form that prevent absorption because they lack FcRn

Question 37

How long do maternal antibodies last?

Answer 37

up to 6 months and degrades over time

Question 38

What causes failure of passive transfer? (FPT)

Answer 38

production failure

ingestion failure of colostrum

failure of GI absorption of maternal immunoglobulins

Question 39

What tests can be used to determine adequate passive transfer?

Answer 39

total protein

salt precipitation

ELISA (SNAP test)

Radial immunodiffusion assay (RID)

Question 40

Why is the TP test precise?

Answer 40

globulins = TP-albumins

Question 41

What kind of test is RID?

Answer 41

Radial immunodiffusion assay done on agar

Question 42

How does age affect treatment for FPT?

Answer 42

<15hrs give 2-3 liters of colostrum

> 15 hrs and <3 weeks give plasma infusion

> 3 weeks watch and give antibiotics

Question 43

When do you recheck a foal after treating for FPT? What are you rechecking?

Answer 43

12-24 hours after tx

checking IgG levels