1a. Objectives (from AD-416):
Improve the detection of BVDV persistently infected animals by ELISA based tests. Activites will include evaluating techniques used in collection, handling and storage of samples as well as attempting to generate improved reagents for inclusion in ELISA test kits.
1b. Approach (from AD-416):
Currently there are two commercial antigen capture ELISA test kits licensed for purchase in the U.S. We will try to see if we can improve the performance of commercial kits by adjusting protocols for samples collection, handling and storage. We will also see if we can generate reagents, such as polyclonal antibodies, monoclonal antibodies and expressed antigens, which will improve the performance of ELISA tests.
3. Progress Report:
This is the final report for this agreement. This research focused on developing improved detection and surveillance for Bovine Viral Diarrhea Virus (BVDV). Most bovine viral diarrhea virus (BVDV) infections can be traced to contact with cattle that have life-long BVDV infections. These animals are called persistently infected (PI) or PI with the virus. Identifying and removing PI cattle from herds is important for preventing BVDV infections and is accomplished using a variety of diagnostic tests. Developing and ensuring the accuracy of these tests requires large amounts of sample material from animals that are PI and animals that are not PI. A common sample used for testing is skin from the ear. Researchers conducted tests to determine if the entire skin of cattle is suitable for use in development and accuracy testing of diagnostic tests. They found that some diagnostic tests can utilize any skin sample, whereas others require skin samples from specific areas. This difference in detection requires that each diagnostic test may be evaluated to determine what types of samples are appropriate. A paper detailing this research was published in a peer reviewed journal. A second study was conducted to compare antigen capture enzyme-linked immunosorbent assay (ACE) testing results using different types of samples from PI animals. The intent was to determine comparative detection rates in types of samples that are frequently submitted to diagnostic laboratories for evaluation of cases of unknown etiology or samples that could be easily collected for BVDV screening. Testing of tail skin fold biopsies, nasal swabs, and ear notch samples resulted in reliable results. In contrast, vaginal/preputial swabs, conjunctival swabs, rectal swabs, and oral swabs were unreliable for diagnosis of persistent infection in calves. A paper detailing this research was published in a peer reviewed journal. A third study looked at the use of measurement of BVDV specific IgA antibodies present in nasal secretions in neonatal calves as a surveillance tool. A draft manuscript detailing these studies has been written and will be submitted to a peer reviewed journal.