Submitted to: Canadian Journal of Veterinary Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/1/2009
Publication Date: 4/1/2009
Citation: Fulton, R.W., Hessman, B.E., Ridpath, J.F., Johnson, B.J., Burge, L.J., Kapil, S., Braziel, B., Kautz, K., Recka, A. 2009. Multiple Diagnostic Tests to Identify Cattle with Bovine Viral Diarrhea Virus and Duration of Positive Tests in Persistently Infected Cattle. Canadian Journal of Veterinary Research. 73(2):117-124. Interpretive Summary: When cattle are exposed to a bovine viral diarrhea virus (BVDV) during gestation the resulting calves may be born with lifelong persistent infections of that BVDV. These animals constantly produce virus which can infect other cattle. A major thrust of BVDV control is to identify and remove BVDV persistently infected animals from production units, feed yards and dairy herds. In this study several different tests were conducted on several different sample types typically collected from cattle. These tests and sample types were compared using 12 different persistently infected cattle. The tests were done over an 11 month time span. It was observed that BVDV persistently infected animals could be more reliably detected using some sample type compared to others. Similarly not all tests were equally reliable in all sample types over time. The most reliable tests were those based on detection of viral proteins in skin cells. These observations are important in that they identify the best tests and sample type to use for the surveillance for animals persistently infected with BVDV.
Technical Abstract: Several tests for bovine viral diarrhea virus (BVDV) were applied to samples collected from twelve cattle persistently infected (PI) with BVDV subtypes common to the U.S.: BVDV1a, BVDV1b, and BVDV2a. These collections were made monthly from December 20, 2005 through November 7, 2006 (day 0 to day 342). The samples collected included clotted blood for serums, nasal swabs, and fresh and formalin-fixed ear notches. The tests utilized included viral titration of nasal swabs and serums for infectious virus; antigen-capture ELISA (ACE) on fresh ear notches, serums, and nasal swabs; polymerase chain reaction (PCR) on serums, nasal swabs, and fresh ear notches; immunohistochemistry (IHC) on formalin-fixed notches; and serology for BVDV antibodies in serums. Of the twelve animals starting the study, three died with mucosal disease (MD). The IHC and ACE tests on ear notches were positive throughout the study as were the serums for ACE and PCR. There was detectable virus in nasal swabs of all cattle throughout the study with the exception of a few that were toxic to cell cultures. The serums had viral titers equal to or > log10 1.6 in all samples of all PI cattle, except for three collections of one animal. The animals under study developed BVDV antibodies due to vaccination or exposure to heterologous PI strains. These antibodies did not appear to interfere with any BVDV test. These studies illustrate that PI cattle may be identified by several tests. However, differentiation of PI cattle from acute BVDV infections of cattle will require additional testing, especially for blood samples and nasal swabs positive on initial test.