Submitted to: American Association of Veterinary Laboratory Diagnosticians
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2006
Publication Date: 10/12/2006
Citation: Fulton, R.W., Whitley, E., Johnson, B.J., Kapil, S., Ridpath, J.F., Burge, L.J., Cook, B., Confer, A.W. 2006. Bovine viral diarrhea virus persistent infections in beef breeding herds: utilization of immunohistochemistry and antigen captive ELISA on ear notches [abstract]. American Association of Veterinary Laboratory Diagnosticians. p. 33. Interpretive Summary:
Technical Abstract: Bovine viral diarrhea virus (BVDV) infections represent significant disease manifestations in cattle. Persistently infected (PI) cattle resulting from fetal infections are considered the major reservoir of virus for susceptible cattle. Beef cattle in stocker and feedlot operations are often where diseases are recorded, yet the breeding herd is where the PI cattle begin. Control programs for BVDV PI cattle identification and removal should start in the breeding herd with proper biosecurity and vaccination programs. An education program was available in 2006 utilizing 31 ranches in southern Oklahoma and northern Texas represented by over 5000 breeding cows. The vaccination history for each ranch was available. The purpose of the project (which is ongoing in 2006 and will be repeated in 2007) is to perform a survey for PI cattle in these 31 ranches using available and validated assays. The objectives of the study included: (1) education program prior to study for the ranchers; (2) testing the bulls prior to breeding season and the 2006 calf crop using the antigen capture ELISA (ACE) test on fresh notches and immunohistochemistry (IHC) on formalin notches. If positive animals were found the tests were repeated and serums obtained for viral growth and BVDV subtyping. If PI calves were found in a herd, the dams' were also tested. There have been 3227 cattle tested representing 27/31 herds. There have been 16/3227 PI cattle identified (0.50%). There have been 4/21 (19.0%) herds with PI calves. Of the 2862 calves tested 15 were PI (0.52%). One herd had 12/349 positive (3.4%) and 1/11 PI calves' dams was PI (9.1%). There were three herds with only 1 PI, 1/134 (0.8%),1/68 (1.5%), and 1/106 (0.9%). By using PCR on the serum of calves from two herds, BVDV1 was identified. Subtyping by genetic sequencing is in progress. In addition to the 16 cattle positive by both IHC and ACE we found three additional ACE positive calves. In an initial examination for pooling of fresh notches and testing by PCR, the samples from one herd were divided into pools of 25. The one positive calf was not detected in a pool of 25. Continued studies are in progress to validate the pooled PCR test. Results of the study reaffirm the detection of less than 1% BVDV PI of a survey population of calves. Finding herds with only one PI calf , is somewhat against the prevailing opinion that PI calves come in large numbers. However, the finding a single PI calf in two herds emphasizes the requirement that any testing utilized, must detect a single PI animal. The vaccine histories will reveal whether vaccines are properly utilized relating to the prevention of BVDV fetal infections.