Vaccines and Vaccine Strategies

Question 1

Why do we vaccinate?

Answer 1

• To prevent clinical disease
• To prevent production losses
• To prevent vertical transmission
• Due to customer request/ export purposes
• To stimulate:Antibody production (IgA,IgG, IgM) AND Cell-mediated immunity (CMI)

Question 2

How does vaccination optimise production ?

Answer 2

• Egg numbers per hen
• Egg shell quality
• Chick quality
• growth rate
• Efficiency
• Minimise mortality and factory condemnations

Question 3

What knowledge do we need in order to design a vaccination strategy?

Answer 3

1. Basic knowledge of diseases
2. Local disease types and incidence
3. Production performance parameters
   4.Technical knowledge of vaccines available
4. the current standard vaccination programme
5. A logical approach!

Question 4

What general vaccines types do we have?

Answer 4

• naturally occurring live mild strain
• Attenuated live field strain
• Inactivated strain
• GM (Gene deleted, gene insertion)

Question 5

What 3 types of live vaccines?

Answer 5

• Naturally mild
• Lab attenuated by passage
• Genetically modified

Question 6

Detail lab attenuated by passage live vaccines

Answer 6

by passage through cell lines or other tissues

Question 7

Detail Genetically modified live vaccines?

Answer 7

• IBD-VP2 insertion into HVT
• ILT insertion into HVT (immunogenic antigen (from ILT or IBD virus) inserted into mild or apathogenic strain (HVT)

Question 8

What is used to chemically inactivate vaccines?

Answer 8

• Formaldehyde
• Beta propiolactone

Question 9

Discuss characteristics of Live vaccines

Answer 9

• Pretty cheap to produce / administer
• Spray/ water/ skin stab
• Freeze dried/ froze n
• Reconstituted
• short term immunity (IgA (local) +/- IgG,M (systemic))
• May cause depression of growth and clinical reactions

Question 10

Describe characteristics of inactivated vaccines

Answer 10

• Expensive to prod/admin
• INJECTION
• Liquid with adjuvant
• RTU presentation
• Longer term immunity (IgG/M) + CMI
• Antigen component not detrimental to animal but can cause local reaction

Question 11

Describe vaccine administration for live vaccines

Answer 11

• Oral, nasal ocular or skin scratch admin
• Water, spray, gel, skin stab
• Repeat doses
• Interference or incompatibility of vaccines overcome by using different routes : Dose 1 spray, Dose 2 water

Question 12

Detail Inactivated vaccine admin

Answer 12

• IM/SC or live vector carrier
• Adjuvant: immuno-modulator, slow release (aluminium hydroxide or mineral oil) can cause local pain
• Often require one or more live priming vaccinations to be most effective

Question 13

What are normal reactions to vaccines?

Answer 13

• Mild or attenuated may cause mild ‘infection’ which in turn stimulates immune system
• may incur production costs

Question 14

What is an ‘adverse’ reaction to vaccine

Answer 14

• Dec BW
• Inc Feed Conversion ratio
  -Inc mortality
• Inc medication costs
• Inc Factory Condmnations

Question 15

List the factors affecting severity of a vaccine ‘ reaction ‘

Answer 15

• Failure of full dose to enter each bird ons aem day
• Ill thirft/ pre-existing morbidity
• Level of MDA
• Strain used
• Dose
• Route
• Timing
• Concurrent immunosuppression
• water, litter and air quality
• Poor husbandry

Question 16

How do we give vaccine through water?

Answer 16

• estimate daily water consumption at day of vaccination
• Duration of vacc (gives volume of water to vaccinate

Question 17

How do we spray vaccinate?

Answer 17

• day old in line sprayer 20ml per 100 chicks
• Ulavac (900mls (20mins spray per 30,000 birds)

Question 18

What are disadvantages of vaccination ?

Answer 18

• Cost:

Admin: vaccine, labour, consumables
To animal: handling, production loss, mortality loss, reversion to virulence

Question 19

Detail disease history when making a vaccination programme

Answer 19

• Specific for site
• regional dx incidence
• NAtional, dx status

Question 20

Detail market rq for when making a vaccination programme

Answer 20

• Health scheme membership - export market rq
• Customer rq

Question 21

Detail cost of disease considerations when making a vaccination programme

Answer 21

• Mortaliy
• Production
• Carcases downgrades
• Medication costs
• Hospital pen costs
• Export losses

Question 22

What vaccine characteristics to consider when making a vaccination programme

Answer 22

– Licenced uses
– Interference of MDA
– Efficacy
– Contraindications
– Duration of immunity
– Cross protection studies
– Vaccine pathogenicity
– Ease of Administration
– Compatibility with other
products
– Competitor products
– Impact on laboratory
testing

Question 23

How do we design vacc protocol for meat lines?

Answer 23

Protect against:
- Mortality
- Production losses

Shorter lived so short duration of immunity needed

Question 24

How do we design vacc programme for parent stock?

Answer 24

• In addition protect against: reproductive & vertically transmitted dx
• Long duration of immunity needed

Question 25

What vaccination exceptions do we have?

Answer 25

• Vaccinate commercial layers
  against Avian Encephalomyelitis
  (AE)
  – Vertically transmitted
  – Cause disease in 2-5 week old
  progeny
• Vaccinated as AE infection can cause
  pale eggs
  – Results in egg downgrades