Recently, TVMDL clients have submitted herd testing for cattle persistently infected (PI) with Bovine Viral Diarrhea (BVD) using TVMDL’s immunohistochemistry (IHC) ear notch test, which costs $20.00 a specimen. While we are looking into possibly discounting testing costs for herds, we would like to suggest an alternate test that is more cost friendly. Testing for PI cattle has traditionally been done using an IHC assay on formalin-fixed ear notch samples. However, PI testing with IHC is time consuming and expensive, requiring diagnostic laboratories to maintain costly reagents and instrumentation. Interpretation requires microscopic review of each sample by a trained veterinary pathologist.
In lieu of this time consuming test is another option, the antigen capture ELISA (AC-ELISA). This test uses Erns glycoprotein specific monoclonal antibodies that effectively detect BVDV antigen in serum and fresh tissues. The Erns glycoprotein exists in an intracellular form as well as in secreted forms, making it an efficient target for BVD detection. This rapid assay takes about 2 hours and with the resources available at TVMDL, we can comfortably process around 1,500 samples a day. The scientific literature shows the AC-ELISA to be every bit as sensitive as IHC in identifying PI animals.
The AC-ELISA test can be performed on either serum (1 mL) or fresh, unfixed ear notch samples. It is a customer friendly test and is less expensive compared to IHC, costing $6.50 per specimen. Turnaround time is considerably faster for the ELISA assay at 1-2 days compared to 2-7 days for IHC. The ELISA test is not validated for pooled testing and, therefore, only individual testing is performed by TVMDL.
Consequently, the AC-ELISA turns out to be the better test not just for TVMDL, but also for our clients doing BVD PI testing. For more information on the test, visit our online test catalog at tvmdl.tamu.edu.