NC1027: An integrated approach to control of bovine respiratory diseases (NC107)
Statement of Issues and Justification
Bovine respiratory disease (BRD) continues to be the most costly disease problem facing the cattle industry. In cattle, respiratory disease occurs as a complex caused by a variety of bacteria and viruses, and exacerbated by management practices. The BRD complex results in losses estimated as high as $3 billion to the US cattle economy annually(29,33,45). One specific example of the importance of this problem is that the Academy of Veterinary Consultants has called for a plan to eradicate bovine viral diarrhea virus (BVDV), a major contributor to BRD(34). The BRD complex has been identified by producers as the leading cause of morbidity and mortality in feedlot cattle(59), and the leading cause of death of weaned dairy heifers(60). A changing agriculture landscape driven by globalized agricultural markets and consumer demand is forcing a changing paradigm in how we manage cattle and their disease, as well as increasing the chances for emergence of new bovine respiratory disease pathogens. Thus research using cutting edge approaches to the identification, treatment, and prevention of disease is needed to allow U.S. cattle producers access to the most current strategies to attack BRD and allow them to maintain a competitive advantage in the global marketplace.Continued research on the nature of factors that put cattle at risk for significant respiratory disease and on the pathogenesis of single agent and multi-agent respiratory diseases is needed. Currently available diagnostic tests and vaccines have limited effectiveness. This is of increasing importance with increased pressure to remove antibiotics from routine management and greatly restrict their use in cattle. Efficient and cost effective diagnostic methods for identification and control of pathogens in the production setting, and management tools that optimize the development of immunological responses to limit infection and disease, must be developed. Failure to develop new monitoring and prevention strategies will result in increasing economic losses to U.S. cattle producers, and increasing animal suffering due to morbidity and mortality associated with respiratory disease.
The committee will consist of a team of researchers with a broad range of experience with the techniques necessary to undertake the research. The scope and complexity of bovine respiratory disease is great. Participating researchers possess the necessary contemporary skills in molecular biology, immunology, virology, bacteriology, and animal management to develop integrated diagnostic and preventative strategies. For example: researchers from LA are part of a center that has developed methods to prepare viral strains optimized for expression of antigens as part of a large system-wide program. They are developing a DNA based bacterial artificial chromosome (BAC)to optimize expression of bovine coronavirus antigens in new vaccines. Others at LA have established models to test the efficacy of antibiotic treatment protocols and use of gene-engineered vaccines in control of BRD. The group from SD has conducted comparative assessment of several methods for diagnosis of bovine viral diarrhea virus and established a system for assessment of maternal vaccination for fetal protection, in conjunction with workers from AL, that has allowed vaccine manufactures to establish claims of fetal protection. These workers have also developed models to assess the interaction between BRD viral agents and the innate immune system of cattle. Researchers from OK have run collaborative trials with workers from several stations of management systems for birth to market reduction in BRD mediated losses. This group has established production level systems for assessment of impact on treatment cost and meat yield/quality as outcomes of their work. TX has provided leadership in the epidemiology of BRD to the committeee. They have also developed production level systems for assessment of vaccine and metaphylactic methods to control BRD, and have determined the effect of BVD persistently infected (PI) cattle on animal productivity in feedlots. GA has worked in the areas of neonatal immune development, vaccine assessment, retained ownership based production level studies of management programs and feedlot AIP/ARDS. They collaborate with SD and others in the assessment of inflammatory function as a pathogenic mechanism in BRD losses and are establishing systems for production scale assessment of inflammation control in management of BRD problems. The group from MI has provided leadership in the application of sensor technology to diagnostic monitoring of BRD agents. CA has provided leadership in the study of polymicrobial disease and the role of type 1 hypersensitivity in BRD. They have established systems that will allow development and production level implementation of new vaccines needed to control BRD in the emerging environment. MN, NADC, IA, MS, and WI have provided leadership in understanding the pathogenesis of bacterial agents involved in BRD. Their work is defining the basis for the next generation of vaccines and management programs to control BRD. KS and NE have established systems that will allow the production of marker vaccines for herpesviruses important to BRD and developed techniques necessary to characterize mechanisms of latency and reactivation by bovine herpesviruses, important to control of BRD. Members of the team have also demonstrated dedication to education of stakeholders, by presenting a Symposium on BRDC at the 2001 Winter Meeting of the Academy of Veterinary Consultants, and by contributing to a new reference on BVDV (Vet Clin N Am, Food Animal, 2004;20:1, "Bovine Viral Diarrhea Virus: Persistence is the Key"); this volume was edited by a member of the Technical Committee of the current project, and 6 of 12 chapters were authored by project members.
Committee members also have relationships with stakeholders in veterinary practitioner groups and cattle producer organizations that will allow communication of new strategies developed by the committee to individuals on the front line of the battle against bovine respiratory disease. The advantage of doing the work as a multistate effort is that we have a documented capacity to interact productively to address the issues critical to minimizing the impact of bovine respiratory disease. We have a history of extending collaborative research outside the bounds of the current and past NC projects into other research and application programs, including proof of concept studies to drive the adoptions of methods to reduce the impact of BRD. Moreover, the impact of bovine respiratory disease crosses state lines. Factors that predispose animals to respiratory disease in one state impact producers who receive the animals after shipment to another state. The ability of scientists from various states to bring their perspectives to a coordinated group attack on the problem of bovine respiratory disease will result in a more balanced and effective approach than would be possible by any state working in isolation.
Likely impacts from successfully completing this work:
- Scientific tools for undertaking a BVDV eradication program as proposed by the Academy of Veterinary Consultants will be put into place; these tools will allow producers to identify and remove persistently infected (PI ) cattle more efficiently and with less expense, minimizing production losses due to BVDV and the associated financial impact.
- A greater understanding of the major virulence mechanisms of Mannhemia haemolytica, Mycoplasma bovis, Pasterurella multocida and Histophilus somni will be developed, allowing distribution of novel therapeutic and intervention strategies to veterinarians and cattle producers, improving efforts to minimize morbidity, mortality, and financial loss due to these agents.
- The characteristics of a safe and effective immune response to bovine respiratory syncytial virus (BRSV) and BVDV will be determined, allowing the development of vaccines that prevent, but do not enhance, disease due to these agents. This will provide producers with tools to decrease disease without the concern of inducing unwanted harmful side effects.
- Improved understanding of the molecular pathogenesis of bovine herpes virus (BHV-10, bovine coronavirus (BC), BVDV, and BRSV will be established, leading to the development of strategies to mitigate the effects of infection by these agents. Because these pathogens are widespread contributors to BRD in U.S. cattle, improved animal health and attendant financial gains will be recognized by producers and veterinarians who utilize updated approaches to control of these agents.
- Knowledge of how current management practices contribute to the development of bovine respiratory disease will be disseminated to veterinarians and cattle producers so that effective management changes can be put into place to decrease the morbidity, mortality, and financial loss that accompanies BRD.
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