kenny v. brock auburn university, college of veterinary medicine bvdv vaccination and prevention of...
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Kenny V. Brock
Auburn University, College of Veterinary Medicine
BVDV vaccination andprevention of reproductiveinfections
Where things began
BVDV Persistently infected animals
Where things began
Herd complaints of reproductive problems
Diagnostic investigations revealed persistent infections
History of vaccination
filtersafehouse
day 0
calving
High risk periodPI
PI
Window of opportunity
Cow breeding cycle
The key to preventing BVDV is to break the cycle of fetal infection which results in persistent infection
BasicHerd Control Program
At birth:Ear notch (IHC test) – all calves
Negative Positive
Retain in herdCull positive animal• Euthanize • Send or Sell for slaughter only
Test dams of positive calvesEar notch (IHC test) or Blood sample (VI)
NegativePositive
Vaccination and fetal protectionVaccination and fetal protection
0
10
20
30
40
50
60
70
80
90
100
Type IIType I
% F
etal
Pro
tect
ion
BVDV challenge strain
Experimental challenge at 75 days of gestation
Modified-LiveVaccination
Vaccination and fetal protectionVaccination and fetal protection
0102030405060708090
100
control vaccinated
BVDV Challenge strain
type Ibtype II
% p
ersi
sten
t inf
ecti
ons
Experimental challenge
at 75 days of gestation
Modified-LiveVaccination (Ia)
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 8 < 1:5 1:5 1:123
Geometric Mean Antibody Titers to BVDV Type 2 (PA131)
•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.
Recommendation:
Bottom line is take an aggressive approach to ensuring heifers are well vaccinated prior to entering breeding herd
Percentage of Persistent Infections against type II
Vaccine Route
Total Number
of Animals
Number of Positive Animals
Percentage (%) PI
Fetuses
PercentProtectio
n
V
ALL 14 1 7% 93%
IM 6 0 0% 100%
SC 8 1 13% 87%
NonVxC NA 8 8 100% 0%
Vaccination and fetal protectionVaccination and fetal protection
0102030405060708090
100
control vaccinated
BVDV Challenge strain
12
% p
ersi
sten
t inf
ecti
ons
Influence of Variability ?
Virulence
Affects outcome of reproductive infections
•Persistent infection•Abortion and repeat breeders•Congenital defects
Influence of Variability ?
Reproductive infectionsVaccine efficacyQuasispecies interactions
day 0
calving
High risk periodPI
PI
Window of opportunity
Cow breeding cycle
filtersafehouse
0
1
2
3
4
5
6
7
8
9
AF HB Lung Liver Spleen Kidney Thymus
Fetal fluids and tissues
BV
DV
Po
siti
ve V
I
Vaccinated
Control
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
BVDV type I BVDV type II
Vaccinated 0/8 8/8
Control 2/7 0/7
Vaccine virus Contaminant
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
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
Prevention of BVDVPrevention of BVDVprevent source of virus exposurevaccinate to provide protection and reduce risksurveillance to determine effectiveness
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
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.
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.