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

Where things began BVDV Persistently infected animals

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

cow calf filter safehouse

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

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

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

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

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

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

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

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

Vaccination and fetal protection % persistent infections

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

Influence of Variability ? Reproductive infections Vaccine efficacy Quasispecies interactions

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

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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

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 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.

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.