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Bovine viral diarrhea virus (BVDV) is one of the most important infectious agent of cattle which is of worldwide concern. Because of the extremely complex disease pathogenesis, it is difficult to establish the economic cost associated with BVDV. This project will provide important information necessary for the development of sound and economical BVDV control and prevention strategies. Not only will producers benefit by reducing economic loss associated with BVDV morbidity and mortality, but consumers will also benefit because of the reduced disease incidence which has both food safety and quality implications. This project will focus on two aspects which are critical to controlling BVDV; 1) Diagnosis of BVDV and 2) BVDV prevention strategies.
NON-TECHNICAL SUMMARY: This project will provide important information necessary for the development of sound and economical BVDV control and prevention strategies. Not only will producers benefit by reducing economic loss associated with BVDV morbidity and mortality, but consumers will also benefit because of the reduced disease incidence which has both food safety and quality implications. For objective 1, we expect to develop and demonstrate new strategies for detecting herds infected with BVDV and cattle peristently infected with BVDV. These strategies would aid veterinarians and producers in economically detecting BVDV infected herds and could be used in large scale BVDV control and eradication efforts. For objective 2, we expect to further define the role that vaccination plays in fetal protection and preventiong bovine respiratory disease and discover ways to optimize this protection.
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APPROACH: Objective 1a: Development of low cost strategies to screen herds for infection with BVDV is needed. To meet this objective, we will compare the use of sentinel animals as a method to screen herds for BVDV infection to individual animal testing. In cooperating herds, a subset of unvaccinated 6 month old calves (sentinels) will be tested for serum virus neutralization antibodies to both genotype 1 and 2 BVDV. At the same time, testing of all individual cattle on the farm will be conducted using pooled rtPCR on skin samples. The presence of VN titers in sentinel animals will be compared to test results from all individual animals. We plan to test this strategy on a minimum of 40 cow-calf herds in the Up[per Peninsula of Michigan. Objective 1b: The identification of cattle persistently infected with BVDV is a key component in the control and prevention of BVDV. Available screening assays are very good at detecting PI cattle; however their cost can be prohibitive and are all are laboratory based. The continued development and evaluation of effective and economical BVDV detection assays is critical to the widespread acceptance of BVDV testing. Current and future research will be aimed at refining and optimizing biosensors for real time and multiplex BVDV detection systems. Testing will continue to emphasize the development of biosensors that can work with a variety of different test substances (whole blood, serum, nasal swabs, and skin samples). These systems have the potential of being deployed patient side and presenting real time results. Objectiv 2a: In past research, we have developed a natural infection model for testing BVDV vaccines effectiveness in preventing fetal infection. Our plans are to extend this model to look at different vaccine strategies in preventing fetal BVDV infections. Variables we intend to examine include types of vaccines (live -vs- killed), timing of vaccines (prebreeding -vs- during pregnancy), and type of viral exposure (different genotypes with different pathogenicity). Objective 2b: Bovine viral diarrhea virus is known to be a part of the bovine respiratory disease complex (BRD), better known as shipping fever. The role that cattle persistently infected with BVDV may play in BRD is unknown. Using a model developed previously, we will continue to study the effect that PI calves have on non-PI cattle in feedlot settings after different intervention strategies are used. Variables that we will look at include types of vaccines used (killed -vs- live or different antigenic make-ups), timing of vaccine administration (pre-arrival -vs- on-arrival in feedlots), and preconditioning programs. Parameters to be measured include morbidity, mortality, growth performance and economic performance. The goal is to establish the importance of PI calves in BRD and the best management schemes to reduce the role that BVDV may play in BRD.