A serosurvey for ruminant pestivirus exposure conducted using cattle sera collected for brucellosis surveillance in the United States

Abstract

Four species of ruminant pestivirus are currently circulating in the United States: Bovine viral diarrhea virus 1 and 2 (BVDV-1, -2; predominant host: cattle), Border disease virus (BDV; predominant host: sheep), and 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. To assess exposure, 2,000 cattle sera, collected between 2014 and 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 reverse transcription-polymerase chain reaction for the presence of pestiviruses; all samples tested negative. The percent of VN-positive samples was 91.3% for BVDV-1, 89.3% for BVDV-2, and 84.9% for HoBi-like viruses. Because the 3 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 (7.6%), titers clearly higher against BVDV-1 (22.2%), titers substantially higher against BVDV-2 (9.1%), BVDV-1 and BVDV-2 titers equivalent but substantially higher than HoBi titers (25.7%), titers substantially higher against HoBi-like viruses (0%), and equivocal (35.4%). Titers tended to be higher against BVDV-1 than BVDV-2. However, the overall percentage of animals with titers below levels considered protective against acute bovine pestivirus infection were ~11% for BVDV-1, 12% BVDV-2, and 18% for HoBi-like virus.

A meta-analysis of bovine viral diarrhoea virus (BVDV) prevalences in the global cattle population

“…Thus, the current control strategy of BVDV vaccination in North America seems to maintain the PI prevalence at a relatively low level but is still not suitable to eradicate BVDV. Approximately 10% of animals reach breeding age without immunological protection against BVDV to vaccination in the US 33 . Possible explanations for the difficulty of eradicating BVDV by using vaccines could be that (i) removal of PI animals must be completed before vaccination, because to the authors’ knowledge vaccination as a successful stand-alone strategy to eradicate BVDV had never been reported in the literature, (ii) a critical vaccination coverage rate should be reached to prevent new persistent infections, (iii) farmers using vaccines often neglect to maintain or implement biosecurity measures 31 , (iv) farmers use vaccines incorrectly, e.g., by applying vaccination after insemination, (v) in general, vaccines are not proven to be fully efficient in the prevention of in-utero transmission of the virus 32 , and (vi) the risk of live BVDV vaccine becoming contaminated with other viruses 15 .…”

“…To increase the variance explained by the factors and to determine their impact on the level of reported prevalences incurred by BVDV infection, it is desirable to have additional information on covariates. These could include management factors such as housing systems 14 , community pasturing activities 11 , artificial insemination 43 , the period when animals were enrolled in BVDV programmes 7 , mortality rate 15 (e.g., influences the transmission rate in the herd due to the reduced number of excreting animals) 44 , lactation and pregnancy status 16 , sex 45 , sensitivity and specificity of diagnostic methods 10 , BVDV genotypes and strains 33 , 46 , herd demographical structure 11 , 43 such as herd size, cattle density and historical herd information such as frequency of purchase and trading activities 30 , 47 . Although we assume that some of this information is indirectly included in the factor “country”, a limitation of our meta-analysis is that not all of these covariates, and other factors such as randomisation of tested animals in the studies, could be taken into account.…”

Serosurvey for Influenza D Virus Exposure in Cattle, United States, 2014–2015

“…We assessed 1,992 banked bovine serum samples for IDV-specific antibodies. The samples, collected between August 2014 and December 2015 as part of the US brucellosis surveillance program, were previously used to screen for ruminant pestivirus and bovine leukemia virus (BLV) exposure ( 26 , 27 ). We aimed to determine the seropositivity rate for IDV and retrospectively compare that rate with seropositivity rates for ruminant pestivirus and BLV from the same samples to identify regional patterns or differences in the US cattle population.…”

“…The serum samples came from both male and female cattle > 2 years of age, raised in 42 states, and were randomly collected from 5 slaughter plants. The states were categorized into 6 regions as previously defined ( 26 ): Pacific West (PW), Mountain West (MW), Upper Midwest (UMW), South Central (SC), Northeast (NE), and Southeast (SE) (Figure 1). The number of samples taken in each slaughter plant, listed by state (California, Florida, Nebraska, Pennsylvania, Minnesota), was proportional to the total annual number of cattle > 2 years of age that had been processed in that plant.…”

Serologic evidence of HoBi-like virus circulation in Argentinean water buffalo

“…The cutoff value to determine the specificity of the serologic response was R = 0.2, and hence different categories were set: samples with R values >0.2 for one pestivirus indicated substantially higher nAb titers for that virus, whereas samples with R values <0.2 for the viruses evaluated were considered equivocal. 4 Also, water buffalo sera were tested by VN against a BVDV-1b strain (Argentinean isolate 25366), which has significant antigenic differences compared to the other pestiviruses evaluated.…”