1. THE SEROLOGICAL RESPONSE INDUCED BY INACTIVATED FMD VACCINE IN ISRAEL – CLINICAL TRIALS IN A DAIRY FARM Ehud Elnekave, Aldo Dekker, Phaedra Eble, Froukje van Hemert-Kluitenberg, Boris Gelman, Nick Storm, Eyal Klement

2. Before we start…
This Presentation is based on the fruits of a PhD performed by Dr. Ehud Elnekave
Israeli Kimron Veterinary institute
Boris Gelman
Nick Storm
CVI, The Netherlands
Aldo Dekker
Phaedra Eble
Froukje van Hemert-Kluitenberg

3. FMD vaccination in Israel
Commercial vaccine - Merial®
High potency dose (PD50≥6)
Same vaccine is used for routine and emergency vaccination
Cattle – Trivalent vaccine (O, A and ASIA-1)
1st vaccination between 2-3 months of age
2nd vaccination up to 3 months later
Annual vaccination

4. Vaccine effectiveness in Cattle – prior experience from Israel
Dairy cattle are rarely affected during FMD outbreaks
When they are affected only young animals show clinical disease
Young animals are (up to two years old) are only partially protected from clinical morbidity despite multiple vaccinations (Elnekave et al. 2013)
Emergency vaccination is highly effective in prevention of clinical and subclinical morbidity (Elnekave et al. 2013)
Elnekave E, Li Y, Zamir L, Even-Tov B, Hamblin P, Gelman B, Hammond J, Klement E. (2013) The field effectiveness of routine and emergency vaccination with an inactivated vaccine against foot and mouth disease. Vaccine. 31:879-85

5. Hypothesis and Questions
It takes more than a certain number of vaccinations to elicit a stable immune response
Age of initial vaccination influences not only the immune response at the initial phase but also at the later stages
What is the number of vaccinations needed to elicit a stable immune response?
What is the ideal age for administration of first vaccination and what is the best vaccination schedule to elicit a good immunological coverage during the first two years of life?

6. Research aims Estimation of the long term antibody dynamics:
Routinely vaccinated cows and heifers of different vaccination statuses
Non vaccinated calves –
After ingestion of colostrum
After vaccination in different ages and different levels of maternal immunity

8. Antibody dynamics in response to vaccination Study design
Vaccination trial
# of animals 54 45
Cows
Heifers
Trivalent –
day 0
≥6 vac.
5 vac.
4 vac.
3 vac.
2 vac.
1 vac.
Trivalent 1 2 4 6 8 12 16 24 36 51 55 77
102
weeks
Trivalent

9. Antibody dynamics in response to vaccination
Vaccine serotype O-4625
Groups vaccinated less than 3 times:
Rapid increase in the antibody titers after vaccination
Followed by quite rapid decrease
Groups vaccinated 4 times or more:
No reaction to vaccine administration
Consistent antibody levels

10. Average neutralizing antibody titer before vaccination in the 1st (a) and the 2nd (b) years

11. Proportion of animals with titers higher than cut of log10=2 during the 1st year

12. The long term effect of age and maternally derived antibodies on the serological response in young dairy calves

13. Maternal Antibody Decay
Half-life=22 days

14. Antibody dynamics in response to vaccination

15. Average neutralizing antibody titers (NAT) above cut-off titer of 2
Average neutralizing antibody titers (NAT) above cut-off titer of 2.0 between the age of six months and 1.5 years

16. Percentage of time over any cutoff

17. Conclusions Five vaccine doses provide long lasting immunity
Given the fact that emergency vaccination is always warranted during an outbreak, the effectiveness of vaccinating after 5 vaccinations should be re-assessed
Vaccination of calves prior to the age of three months does not elicit good AB response not just after vaccination but also impairs the entire immunological response later on.

18. Thanks!