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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Ruminant Diseases and Immunology Research » Research » Publications at this Location » Publication #329148
Title: A serosurvey for ruminant pestivirus exposure conducted using cattle sera collected for brucellosis surveillance in the United States

Author
item BAUERMANN, FERNANDO - Universidade Federal De Santa Maria
item Ridpath, Julia
item DARGATZ, D - Animal And Plant Health Inspection Service (APHIS)

Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2016
Publication Date: 1/30/2017
Citation: Bauermann, F.V., Ridpath, J.F., Dargatz, D.A. 2017. A serosurvey for ruminant pestivirus exposure conducted using cattle sera collected for brucellosis surveillance in the United States. Journal of Veterinary Diagnostic Investigation. 29(1):76-82. doi: 10.1177/1040638716680251.

Interpretive Summary: Pestiviruses are a group of viruses that infect livestock including cattle, pigs and sheep. Infection with pestiviruses cause substantial losses to the agricultural economy. Three types of pestiviruses infect cattle. These three types of viruses are known as bovine viral diarrhea virus type 1 (BVDV1), bovine viral diarrhea virus type 2 (BVDV2) and HoBi-like viruses. The purpose of this study was to get an estimation of the proportion of cattle in the contiguous United States that have been exposed to these three pestiviruses. To do this, blood samples were collected from 2000 cattle originating throughout the contiguous United States. These samples were tested to determine if they contained antibodies against BVDV1, BVDV2 and HoBi-like virus. Based on the results of testing the cattle were separated into 6 categories; no antibodies (7.9%), antibody level higher against BVDV-1 (23.5%), antibody level higher against BVDV-2 (9.6%), BVDV-1 and BVDV-2 antibody level equivalent but clearly higher than HoBi-like level (27.2%), level higher against HoBi-like viruses (0%) and samples with levels of antibodies similar against all viruses (31.8%). These results indicate that BVDV1 strains predominate in the lower 48 states, followed by BVDV2 strains with little or no exposure to HoBi-like virus stains. These finding are in agreement with previous studies that characterized viruses isolated from infected cattle. Further, these results indicate that despite BVDV vaccines being available since the 1960’s and widely used, one in ten mature animal have no protection against BVDV-1 or BVDV-2 infections. That number rises to nearly 1 in 5 animals that have no protection against HoBi-like viruses. Currently there are no vaccines against HoBi-like viruses. This is the largest nationwide serology study for bovine pestivirus exposure conducted to date. Regular monitoring of this sort is necessary to track the effectiveness of control measures.

Technical Abstract: Four species of ruminant pestivirus are currently circulating in the United States (U.S.): Bovine viral diarrhea virus (BVDV) types 1 and 2 (predominant host cattle), Border disease virus (BDV) (predominant host sheep) and the Pronghorn virus (sporadically detected in wild ruminants). A third bovine pestivirus called HoBi-like virus has been detected in cattle and water buffalo in South America, Asia and Europe. To date no isolations of HoBi-like viruses from U.S. cattle have been reported. Here, 2000 cattle serum samples collected between 2014-2015, as part of the U.S. brucellosis surveillance program, were tested for antibodies against BVDV-1, BVDV-2 and HoBi-like viruses. In addition, RNA was extracted and tested by RT-PCR for the presence of pestiviruses. All samples tested negative for each of the three viruses by RT-PCR. The percent of VN positive samples was 91.3%, 89.3%, and 84.9% for BVDV-1, BVDV-2 and HoBi-like viruses respectively. Because the three bovine pestiviruses are antigenically cross-reactive the comparative level of antibody against each pestivirus species was determined. Based on comparative titers samples were segregated into 6 categories; no titers (7.9%), titers clearly higher against BVDV-1 (23.5%), titers clearly higher against BVDV-2 (9.6%), BVDV-1 and BVDV-2 titers equivalent but clearly higher than HoBi titers (27.2%), titers substantially higher against HoBi-like viruses (0%) and equivocal (31.8%). Titers tended to be higher against BVDV-1 than BVDV-2. Still, the overall percentage of animals with titers below levels considered protective against acute bovine pestivirus infection were about 11% for BVDV-1, 12% BVDV-2 and 18% for HoBi-like virus.