1. Kenny V. Brock BVDV vaccination and prevention of reproductive
infections
Kenny V. Brock
Auburn University, College of Veterinary Medicine

2. Where things began
BVDV Persistently infected animals

3. cow calf Where things began Herd complaints of reproductive problems
Diagnostic investigations revealed persistent infections
History of vaccination
cow
calf

4. cow
calf
filter
safehouse

5. Window of opportunity day 0 High risk period PI PI calving
Cow breeding cycle

6. The key to preventing BVDV is to break the cycle of fetal infection which results in persistent infection
cow
calf

7. Test dams of positive calves
Basic
Herd Control Program
At birth:
Ear notch (IHC test) – all calves
Negative
Positive
Test dams of positive calves
Ear notch (IHC test) or Blood sample (VI)
Cull positive animal
Euthanize
Send or Sell for slaughter only
Retain in herd
Negative
Positive

9. Vaccination and fetal protection
Modified-Live
Vaccination
Experimental challenge
at 75 days of gestation
% Fetal Protection
Type I
Type II
BVDV challenge strain

10. Vaccination and fetal protection
Modified-Live
Vaccination (Ia)
Experimental challenge
at 75 days of gestation
% persistent infections

11. Geometric Mean Antibody Titers to BVDV Type 2 (PA131)
Vaccine
Route N
Study Day
Baseline 6/20/03
11/24/03
2/9-11/04
0 DV1
Challenge
C-Section V
ALL 14
1:6
1:13
1:160 IM 6
1:5
1:8
1:113 SC 8
1:7
1:18
1:207
NVC NA
< 1:5
1:123

12. Recommendation:
Administer minimum of 3 doses of vaccine during early development of heifers (1-2 doses of MLV)
Follow by annual administration of vaccine in cow herd.
Bottom line is take an aggressive approach to ensuring heifers are well vaccinated prior to entering breeding herd

13. Percentage of Persistent Infections against type II
Vaccine
Route
Total Number of Animals
Number of Positive Animals
Percentage (%) PI Fetuses
Percent
Protection V
ALL 14 1 7%
93% IM 6 0%
100% SC 8
13%
87%
NonVxC NA

14. Vaccination and fetal protection
% persistent infections

15. Influence of Variability ?
Virulence
Affects outcome of reproductive infections
Persistent infection
Abortion and repeat breeders
Congenital defects

16. Influence of Variability ?
Reproductive infections
Vaccine efficacy
Quasispecies interactions

17. Window of opportunity day 0 High risk period PI PI calving
Cow breeding cycle

18. cow
calf
filter
safehouse

19. with a commercial MLV vaccine containing a NCP type 1a BVDV strain
a, b P < 0.05
Figure 1. Virus isolation from fetuses recovered from vaccinated and unvaccinated cows
with a commercial MLV vaccine containing a NCP type 1a BVDV strain

20. BVDV type I
BVDV type II
Vaccinated
0/8
8/8
Control
2/7
0/7
Vaccine virus
Contaminant

21. Where to from here ? How will control influence vaccination?
live vaccines present a risk
Adjust antigenic background of vaccine
Define longevity of protection
Be prepared to adapt

22. Conclusions of fetal protection studies
Antigenic components of vaccine are
important in providing broad protection
Modified-live vaccines generally provide
higher levels of protection
Abortions are related to strain differences
Biosecurity is essential

23. Prevention of BVDV prevent source of virus exposure
vaccinate to provide protection and reduce risk
surveillance to determine effectiveness
Clinically, BVDV infections can be grouped into basically 2 groups. Acute infections may occur in any immunocompetent animal. Infection of the fetus prior to the development of immunocompetence, which occurs at approximately 125 days of gestation , may result in fetal death or lifelong, persistent, immunotolerant infections.

24. Manage cow herd to reduce risks
Avoid movement during highest risk period of gestation (O to 150 days of gestation)
Avoid exposure to other groups during highest risk period of gestation (O to 150 days of gestation)
Avoid purchase of pregnant animals

26. Try this ten step program
1. Maintain a strict level of herd biosecurity.
2.  Purchase only open animals that are known to be BVDV-negative prior to purchase.
3.  Isolate any new additions or animals re-entering the herd for a minimum of 30 days.
4.  Test any new additions for BVDV and vaccinate during the quarantine period.
5.   Maintain good sanitation and routinely disinfect contaminated areas. Prevent contamination from outside sources by disinfection.

27. ten step program…..
6.   Prevent contact with neighboring animals of unknown status.
7.   Protect pregnant animals from potential sources of exposure during the first trimester.
8.   Prevent mixing of animal groups immediately prior to breeding and during the first trimester.
9.   Conduct surveillance for BVDV by performing necropsy on dead animals and collect ear notch/blood samples on any calves that are poor-doers and calves that have respiratory disease.
10.  Vaccinate the cow herd on an annual basis. Ensure that heifers are vaccinated at 6 months of age, boostered 30 days later, and revaccinated prior to breeding.