This study examined the impact of maternally derived antibodies (MDAs) on foot-and-mouth disease (FMD) vaccination in calves on a large dairy farm in an endemic country. The study found huge variation in MDA levels between calves despite optimal colostrum practices. Adjusting the calf vaccination strategy is critical to ensure most calves are actively immunized and protected from infection and disease spread. Delaying vaccination by one month resulted in a period of significantly lower virus neutralizing antibody titers and increased susceptibility to FMD virus.

1. MATERNALLY DERIVED ANTIBODIES TO FMD IN CATTLE:
IS INTERFERENCE ON FMD VACCINATION APPROPRIATELY CONSIDERED ?
EuFMD Open Session. Special edition 2020
C.Hamers, V.Broks, P. Giskus, M. Alnahrawy, N.Denormandie, P.Hudelet
Introduction
Material and Methods
Results and Discussion
Conclusion
Little data is available on how Maternally Derived Antibodies (MDAs) interfere with FMD vaccination in susceptible species and the potential
interference of MDAs on FMD vaccine uptake is largely underestimated. This is particularly true when intensive FMD vaccination programs are
in place for adults, resulting in high levels of MDAs in the young stock.
We report here the results of a Post Vaccination Monitoring (PVM) study conducted in a large dairy herd located in an endemic country.
The study was conducted in a dairy farm with “state of the art” practices. The farm is located in an FMD endemic country with high infection
pressure. Adults are vaccinated 4 times per year with Aftovaxpur. Calves are fed with high quality colostrum. To limit MDA interference, calves
are repeatedly vaccinated against FMD at a month interval, between 2.5 and 6.5 months of age (4 injections).
To assess the calf vaccination program, MDA levels of calves were measured before vaccination. We then compared the current vaccination
(Group 2) to an earlier and to a later program. Comparisons were based on VNT against O-Manisa, measured on serum samples taken at regular
intervals.
The impact of MDAs on vaccine uptake is largely underestimated. MDAs are frequently seen as a homogeneous parameter that can be managed
based on average antibody levels over time. This study shows that, in a perfectly managed dairy herd, there can be huge differences in MDA
levels. Receptivity of the calves to vaccination and susceptibility to infection vary accordingly. Therefore, adjusting the vaccination strategy
of the calf category, so that most calves are actively immunized is critical. This is not only to protect calves from disease, but also to prevent
that calves become a hotspot of dissemination for the production herd.
Similar results were obtained in other large dairy herds. Such herds have some specificities, among which optimal colostrum distribution.
Heterogeneity of the colostrum antibody levels would be even higher in beef cattle, resulting in a higher disparity of FMD vaccine uptake.
The VPH Center, Boehringer Ingelheim Animal Health, 29 avenue T Garnier, Lyon France
© : Boehringer Ingelheim, all rights reserved
The average Virus Neutralizing Titers (VNTs) at 2.5 months of age, before any vaccination, was 1.73 Log10. Despite the care regarding
colostrum administration, a 10-fold difference was observed (1.24 Log10-2.29 Log10) between extremes (Figure 1).
Among the tested vaccination programs, the one currently in place looked appropriate. There was no benefit to add an earlier vaccination.
Delaying the vaccination program by a month (Group 3) resulted in a period with significantly lower VNTs with a risk of increased
susceptibility to infection.
Figure1: Dispersion of MDA titres at
2.5 months of age
Figure2: Mean evolution of VNT according to the vaccination program, the circled
zone shows significantly lower VNTs in group3
Groups
Nb calves
per group
Age in months
2.5 3.5 4.5 5.5 6.5 7.5
1 15 V, B V, B V, B V, B V, B B
2 15 B V, B V, B V, B V, B B
3 15 B B V, B V, B V, B B
V : vaccination ; B: blood sampling
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
2.5 3.5 4.5 5.5 6.5 7.5
Months of age
Log10 VNT O Manisa
Group 1
Group 2
Group 3
Log10VNTOManisa
Box-and-Whisker Plot
1
1.5
2
2.5