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

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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.