Submitted to: National Cattlemens Beef Association Annual Meeting
Publication Type: Abstract only
Publication Acceptance Date: 1/30/2006
Publication Date: 1/30/2006
Citation: Crossley, B., Ridpath, J.F., Parr, B., Hullinger, P., Hietala, S. 2006. A novel BVDV 1 subgenotype detected in a closed beef herd in California 2005. BVD Symposium, National Cattlemen's Beef Association Annual Meeting. Paper No. 17. p. 35. Interpretive Summary:
Technical Abstract: Historically BVDV isolated from cattle in the U.S. belong to one of three subgenotypes, BVDV1a, BVDV1b and BVDV2a. Here we report the isolation of a novel BVDV subgenotype from a ten year old Limousin-cross beef cow from a closed herd submitted for necropsy by the owner to the California Animal Health and Food Safety Laboratory (CAHFS), Davis, California. She had not calved in the past 2 years and her two prior calves were poor doers as observed and reported by the owner. The submitted animal had a one day history of dehydration and not eating or drinking. The herd had not received any vaccines since 1988. At necropsy, mild multifocal epithelial necrosis and ulceration was found in the moderately autolyzed esophagus, abomasal mucosa and small and large intestine. Although initial FA (1:30 dilution of porcine anti-BVDV polyclonal antisera, American BioResearch Laboratories, TN)) was only weak positive for BVDV, immunohistochemistry (1:20 dilution of 15.c.5 anti BVDV EO Mab cell culture supernatant supplied by Dr. Amy Glase) detected BVD antigen in virtually every tissue examined including epithelium of the entire GI tract with muscle, intestinal smooth muscle, vessel endothelium, mammary gland epithelium, hepatic Kupffer cells, renal tubular epithelium, splenic cord mononuclear cells, epithelial and stromal cells of the lung, as well as neurons and select glial cells in the brain. While spleen tissue tested negative for the presence of BVD virus by qRT PCR as determined by binding of BVDV specific probe, a band of expected molecular weight was detected by gel electrophoresis suggesting BVDV specific amplification but failure of the probe to bind. The amplicon was sequenced and phylogenetic analysis using NCBI GenBank reference isolates identified the closest match as BVDV virus ABO42670, a Japanese isolate, which was linked to South African isolates grouped as BVDV-1c. Further analysis of the California amplicon revealed a 28bp deletion (bp 102-130, Ridpath, 1996) and two mismatches specifically in the probe binding region. Phylogenetic analysis grouped this isolate with BVD type 1 isolates, however in a distinct subgroup outside of BVD-1a and BVD-1b. The remainder of the herd was tested by PCR for the presence of BVDV and for BVDV antibody levels by serum virus neutralization. All samples tested were negative for BVDV by PCR and gel electrophoresis, whereas serology identified significantly elevated titers as high as 1:4096 to BVD-1 suggesting exposure to field strain. To our knowledge this is the first report of the apparently atypical BVDV strain in the United States.