<OL> <LI> Identify emerging and re-emerging agents and develop diagnostic methods for bovine respiratory disease. <LI> Characterize the mechanisms and intervention targets in the pathogenesis of bovine respiratory disease at the molecular, cellular and host level. <LI> Develop intervention strategies for critical control points to reduce impact of bovine respiratory disease.
NON-TECHNICAL SUMMARY: Bovine respiratory disease remains as a major economic problem in cattle and dairy production in the United States. This project will result in better surveillance and diagnosis of the disease, increase understanding of the disease mechanism, and will provide more effective means to control bovine respiratory disease.
APPROACH: Summary data will be provided from the Michigan Animal Health Diagnostic Laboratory on surveillance of existing, emerging, and re-emerging bovine respiratory pathogens to determine changes in disease patterns. Rapid diagnostic tests for the detection of bovine viral diarrhea virus will be developed. Testing strategies for screening cattle herds for screening cattle herds for bovine viral diarrhea virus infection will be developed using serologic test on sentinel heifers. The effects of cattle persistently infected with bovine viral diarrhea virus on feedlot performance will be characterized. Studies will be conducted to determine the mechanisms of virulence in acute bovine viral diarrhea virus infection including the induction of thrompocytopenia. The effects of bovine viral diarrhea virus infection on endocrine function will be elucidated to determine if disruption of endocrine function plays a role in disease pathogenesis. Mucosal immunity to bovine viral diarrhea virus will be characterized and its importance to protective immunity will be characterized. Studies will be study to determine the optimal time of vaccination against bovine respiratory disease pathogens in preconditioning programs for feeder calves.
PROGRESS: 2001/10 TO 2006/09 <BR>
The goal of this project was to develop a rapid, low cost, animal side diagnostic assay for detecting cattle persistently infected with bovine viral diarrhea virus (BVDV). We developed and evaluated a conductometric biosensor that was capable of detecting virus in blood, nasal swabs and skin samples collected from cattle persistently infected with BVDV. The first objective of the study was to assess the performance of the biosensor in the positively known blood serum, nasal swab and ear-notch samples. The second objective was to test for BVDV infection in unknown field samples. The conductometric biosensor consisted of two parts: an immunosensor and an electronic data collection system. The immunosensor was comprised of four, one-time-use, disposable membranes: sample application membrane, conjugate membrane, capture membrane, and absorption membrane. Silver electrodes were fabricated on the capture membrane to electrically connect the immunosensor to the electronic data acquisition system consisting of a copper wafer and an ohmmeter linked to a computer. Initial testing on known samples from BVDV PI animals showed that ear-notch elute samples produced the best sample matrix for detecting BVDV when compared to blood or nasal swabs. Subsequently, thirty ear-notch samples that were previously diagnosed with BVDV infection were tested. Twenty-seven of the thirty samples (90%) were classified correctly. The biosensor was then used to detect BVDV in 70 unknown ear-notch samples and compared to results obtained by the Diagnosis Center for Population and Animal Health using an antigen-capture ELISA (AC-ELISA). Unfortunately, the biosensor was unable to detect the presence of BVDV in three positive samples but was specific enough to produce a negative response in all 67 negative (non-infected) samples. The inability of the biosensor to detect the presence of BVDV in these samples may be due to the high variability observed in the signal response. A rapid low cost biosensor has been developed that can detect BVDV in multiple sample types collected from cattle persistently infected with the virus. Current research is trying to resolve variability in the biosensor response that may be affecting accuracy.
IMPACT: 2001/10 TO 2006/09<BR>
Cattle persistently infected with bovine viral diarrhea virus (BVDV) are the major source of virus spread within and between farms. Detecting and eliminating these animals is critical for the efficient control of this important virus. An inexpensive and rapid conductimetric biosensor platform for detecting BVDV has been developed and initially tested. Rapid and cost effective detection of cattle persistently infected with BVDV will significantly enhance BVDV control programs both national and globally. Additionally, the developed technology can potentially be adapted to many important pathogens.