Bovine tuberculosis has nearly been eradicated from the United States because of the success of the State-Federal Bovine Tuberculosis Eradication Program.2 However, finishing this task with current fiscal constraints will require better use of existing diagnostic tests and development of improved tests. Research is needed to develop a better understanding of the pathogenesis of tuberculosis in animals so that improved tests and control strategies can be developed.

Bovine tuberculosis research programs were initiated by the United States Department of Agriculture and several universities in 1992. Scientists met in August, 1992, at the First Workshop on Diagnostic Techniques for Bovine Tuberculosis to discuss and identify research priorities. Thirty-three scientists representing four countries and 12 universities and federal agencies participated in the Workshop, which was held at the National Veterinary Services Laboratories, Ames, Iowa.

In June, 1994, the Second Workshop on Diagnostic Techniques for Bovine Tuberculosis was held at the National Animal Disease Center, Ames, Iowa, for the purpose of reporting results of research conducted since 1992. There were 64 participants from seven countries representing 22 universities and government agencies. Twenty research papers were presented during the one-and- a-half day meeting. Most of the reports focused on evaluation of existing diagnostic tests and molecular epidemiology of Mycobacterium bovis isolates.

Currently, research efforts on bovine tuberculosis are directed toward accomplishing the following generalized objectives:

1. Evaluate tests for diagnosis of tuberculosis in cattle, deer, elk, and llama.

2. Develop improved diagnostic tests.

3. Determine molecular mechanisms of M. bovis infection.

4. Develop methods for differentiation of M. bovis strains.

5. Develop vaccines to protect against M. bovis infection.

 

Specific objectives for research being conducted at each of four universities and two federal agencies in the United States are as follows:

1. Comparison of the sensitivity of the caudal fold skin test and a commercial gamma-interferon assay for diagnosis of bovine tuberculosis.

2. Analysis of tuberculins used in the United States, Canada, and Mexico.

3. Factors affecting results of cell-mediated immune tests for diagnosis of bovine tuberculosis.

4. Diagnosis and pathogenesis of M. bovis infection in elk.

5. Pathogenesis of M. bovis infection in cattle.

6. Immunohistochemical detection of M. bovis in formalin-fixed paraffin-embedded tissues.

7. Restriction fragment length polymorphism analysis of diverse M. bovis isolates.

 

1. Comparison of the NVSL (U.S.) and Pronabive (Mexico) methods for production of PPD tuberculins.

2. Use of Microbial Identification (MIDI) system to identify M. bovis and determine subspecies differences.

3. Diagnosis of M. bovis infection in llamas.

 

1. Genetics of macrophage function and natural disease resistance against tuberculosis in cattle.

2. The role of macrophage function in natural disease resistance against bovine tuberculosis.

3. Development of new bovine tuberculosis vaccines.

4. Use of T-cell clones to identify protective immunogens of M. bovis.

5. DNA species-specific probes for the diagnosis of brucellosis and tuberculosis.

 

1. Develop DNA probes for use in diagnosis and molecular epidemiology.

2. Develop specific monoclonal antibodies for use in diagnostic tests.

3. Evaluate production of tumor necrosis factor as an indicator of cell-mediated immune response.

4. Develop improved methods for isolation of M. bovis.

5. Develop methods for differentiation of M. bovis isolates by gas chromatographic analysis of bacterial fatty acids.

 

1. Use of ELISA for diagnosis of tuberculosis in anergic animals.

 

1. Field evaluation of a five antigen panel ELISA system for the serological diagnosis of M. bovis in animal species.

2. Analysis of culture filtrate proteins from M. bovis field isolates.

3. Fingerprinting of M. bovis by ERIC-PCR.

4. Detection of M. bovis in tissue samples by use of PCR and DNA probes.

 

Bovine tuberculosis research is also being conducted in Mexico and Canada as well as many other countries around the world. Scientists are working in collaboration with each other to maximize use of limited resources and avoid unnecessary duplication of effort.

An International Symposium on Bovine Tuberculosis in Animals and Human Beings will be held May 8-11, 1995, at the University of Maryland, College Park, Maryland. The Symposium is sponsored by the United States Department of Agriculture, Centers for Disease Control and Prevention, National Institutes of Health, and the Agricultural Ministries of Australia, Canada, Mexico, and New Zealand. In addition, the 2nd International Conference on Mycobacterium bovis will be held August 28 through September 2, 1995, in Dunedin, New Zealand. These meetings will bring together scientists from around the world to communicate the most recent findings of bovine tuberculosis research.

1. Whipple DL: 1994, Overview and Progress Report on Tuberculosis Research. Proc Annu Meet US Anim Health Assoc 98:572-574.

2. VanTiem JS: 1994, Status of the State-Federal Bovine Tuberculosis Eradication Program: Fiscal Year 1994. Proc Annu Meet US Anim Health Assoc 98:539-555.