Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2008
Publication Date: 5/1/2009
Citation: Ridpath, J.F., Chiang, Y.W., Waldbillig, J., Neill, J.D. 2009. Stability of Bovine Viral Diarrhea Virus Antigen in Ear Punch Samples Collected from Bovine Fetuses. Journal of Veterinary Diagnostic Investigation. 21(3):346-349. Interpretive Summary: Infection of pregnant cattle with bovine viral diarrhea virus (BVDV) results in the persistent infection of the calf. While some of the resulting persistently infected calves are born alive, many die before birth and are expelled as abortions or stillbirths. Correctly diagnosing aborted or stillborn animals as infected with BVDV can be difficult due to breakdown of tissues that occurs between death and expulsion from the cow or between expulsion and discovery in the pen. It was demonstrated in this study that BVDV can be detected from punches taken from the ear after exposure to light, air and elevated temperatures for seven days. The considerable drying that occurred under different storage conditions did not affect diagnosis. These results suggest that testing of skin samples collected from aborted fetuses and stillborn calves found in the field may represent a practical method of diagnosing BVDV reproductive disease.
Technical Abstract: Fourteen first calf heifers were tested free of BVDV antibodies by serum neutralization and free of BVDV by PCR. Twelve of the heifers were exposed to BVDV1b strain CA0401186a between 84-86 days of gestation. Two of the heifers were exposed to mock inoculum and served as negative controls. Fetuses were harvested, by cesarean section, at 115-117 days of gestation. The twelve fetuses removed from the CA0401186a exposed heifers were BVDV positive based on virus isolation from kidney, thymus, cerebellum and spleen. Virus was not isolated from the fetuses of control animals. Ear punch samples were collected from all fetuses at time of harvest. Antigen capture ELISA (ACE), using a commercial kit, was performed on ear punch samples that were frozen within 5 hrs of collection and stored at -20ºC until tested, tested after storage for 7 days at room temperature (18º - 25ºC) (rmt) or tested after storage for 7 days at 37ºC. Samples stored for 7 days at rmt or 37ºC lost an average of 34% of their starting weight. All samples from BVDV isolation positive fetuses tested positive by ACE, regardless of storage conditions. Tissues collected from fetuses of control heifers always tested negative by ACE, regardless of storage conditions. These results suggest that ACE testing of skin samples collected from aborted fetuses and stillborn calves found in the field may represent a practical method of diagnosing BVDV reproductive disease.