Bovine Viral Diarrhea Virus Type Research Articles

Human and bovine viruses in the Milwaukee River watershed: Hydrologically relevant representation and relations with environmental variables

To examine the occurrence, hydrologic variability, and seasonal variability of human and bovine viruses in surface water, three stream locations were monitored in the Milwaukee River watershed in Wisconsin, USA, from February 2007 through June 2008. Monitoring sites included an urban subwatershed, a rural subwatershed, and the Milwaukee River at the mouth. To collect samples that characterize variability throughout changing hydrologic periods, a process control system was developed for unattended, large-volume (56–2800L) filtration over extended durations. This system provided flow-weighted mean concentrations during runoff and extended (24-h) low-flow periods. Human viruses and bovine viruses were detected by real-time qPCR in 49% and 41% of samples (n=63), respectively. All human viruses analyzed were detected at least once including adenovirus (40% of samples), GI norovirus (10%), enterovirus (8%), rotavirus (6%), GII norovirus (1.6%) and hepatitis A virus (1.6%). Three of seven bovine viruses analyzed were detected including bovine polyomavirus (32%), bovine rotavirus (19%), and bovine viral diarrhea virus type 1 (5%). Human viruses were present in 63% of runoff samples resulting from precipitation and snowmelt, and 20% of low-flow samples. Maximum human virus concentrations exceeded 300genomiccopies/L. Bovine viruses were present in 46% of runoff samples resulting from precipitation and snowmelt and 14% of low-flow samples. The maximum bovine virus concentration was 11genomiccopies/L. Statistical modeling indicated that stream flow, precipitation, and season explained the variability of human viruses in the watershed, and hydrologic condition (runoff event or low-flow) and season explained the variability of the sum of human and bovine viruses; however, no model was identified that could explain the variability of bovine viruses alone. Understanding the factors that affect virus fate and transport in rivers will aid watershed management for minimizing human exposure and disease transmission.

Comparison of milk production changes in adult Holstein cows vaccinated with a 5-way modified-live virus vaccine containing a Mannheimia haemolytica toxoid versus a 5-way modified-live virus vaccine containing a 5-way Leptospira bacterin

A total of 105 Holstein cows 21 to 31 days-in-milk were vaccinated with a 5-way modified-live virus (MLV) vaccine containing bovine herpesvirus-1, bovine viral diarrhea virus (types 1 and 2), parainfluenza-3 virus, and bovine respiratory syncytial virus combined with either a Mannheimia haemolytica toxoid or a 5-way Leptospira bacterin. Milk production was monitored for 3 days pre- and 3 days post-vaccination. There was a 0.52 lb (0.24 kg) increase in mean milk production for the group vaccinated with the 5-way MLV vaccine plus 5-way Leptospira bacterin. There was a 0.32 lb (0.15 kg) decrease in mean milk production in the group vaccinated with the 5-way MLV vaccine plus M. haemolytica toxoid. The difference in mean milk production between the 2 groups was 0.85 lb (0.38 kg) (P=0.4076). There was no statistical difference in mean daily milk production changes between treatment groups when parity was taken into account. Vaccination during lactation using a M. haemolytica toxoid in combination with a 5-way MLV vaccine resulted in a small, but insignificant, decrease in milk production.

Recombinant pestivirus E2 glycoproteins prevent viral attachment to permissive and non permissive cells with different efficiency

Bovine viral diarrhoea virus (BVDV) is an economically important animal pathogen, which like other pestiviruses has similar molecular biological features to hepaciviruses, including human Hepatitis C virus. The pestivirus E2 glycoproteins are the major target for virus-neutralising antibodies, as well as playing a role in receptor binding and host range restriction.In this study, recombinant E2 glycoproteins (rE2) derived from three different pestivirus species were examined for their inhibitory effects on pestivirus infectivity in cell culture. Histidine-tagged rE2 glycoproteins of BVDV type 2 strain 178003, BVDV type 1 strain Oregon C24V and CSFV strain Alfort 187 were produced in Spodoptera frugiperda insect cells and purified under native conditions. The ability of rE2 glycoprotein to inhibit the infection of permissive cells by both homologous and heterologous virus was compared, revealing that the inhibitory effects of rE2 glycoproteins correlated with the predicted similarity of the E2 structures in the recombinant protein and the test virus. This result suggests that the sequence and structure of E2 are likely to be involved in the host specificity of pestiviruses at their point of uptake into cells.

Immunogenicity of an inactivated Chinese bovine viral diarrhea virus 1a (BVDV 1a) vaccine cross protects from BVDV 1b infection in young calves

Bovine viral diarrhea virus (BVDV) 1a and 1b strains are the predominant subgenotypes in China. Because of the genetic and antigenic variability among different BVDV strains, a vaccine effective in one region may fail to protect against infections caused by different virus strains in another region. No BVDV vaccine developed with the predominant strains in China are available. In this study, the immunogenicity of an inactivated Chinese BVDV 1a NM01 vaccine strain was evaluated by challenging with a Chinese BVDV 1b JL strain. Ten 2–4-month-old calves were intramuscularly vaccinated with a single dose of the vaccine strain and boosted with same dose three weeks after the first vaccination, with five mock immunized calves serving as a control group. The average titer of neutralization antibody to BVDV 1a and BVDV 1b of immunized calves reached 1:410 and 1:96, respectively, at 21 days post the second vaccination. Twenty-one days post the second vaccination, all calves were challenged with strain JL. The clinical signs, such as the temperature and leukopenia of the immunized calves and viral shedding, were significantly less than the mock immunized calves after challenging with the virulent BVDV 1b strain, indicating that the BVDV 1a vaccine strain elicited efficacious protection against the endemic BVDV 1b strain in China. To the best of our knowledge, this is the first report of an inactivated BVDV vaccine which demonstrated effective cross-protection against BVDV type 1b infection in China.

Mixed Triple: Allied Viruses in Unique Recent Isolates of Highly Virulent Type 2 Bovine Viral Diarrhea Virus Detected by Deep Sequencing

In February 2013, very severe acute clinical symptoms were observed in calves, heifers, and dairy cattle in several farms in North Rhine Westphalia and Lower Saxony, Germany. Deep sequencing revealed the coexistence of three distinct genome variants within recent highly virulent bovine viral diarrhea virus type 2 (BVDV-2) isolates. While the major portion (ca. 95%) of the population harbored a duplication of a 222-nucleotide (nt) segment within the p7-NS2-encoding region, the minority reflected the standard structure of a BVDV-2 genome. Additionally, unusual mutations were found in both variants, within the highly conserved p7 protein and close to the p7-NS2 cleavage site. Using a reverse genetic system with a BVDV-2a strain harboring a similar duplication, it could be demonstrated that during replication, genomes without duplication are generated de novo from genomes with duplication. The major variant with duplication is compulsorily escorted by the minor variant without duplication. RNA secondary structure prediction allowed the analysis of the unique but stable mixture of three BVDV variants and also provided the explanation for their generation. Finally, our results suggest that the variant with duplication plays the major role in the highly virulent phenotype. This study emphasizes the importance of full-genome deep sequencing in combination with manual in-depth data analysis for the investigation of viruses in basic research and diagnostics. Here we investigated recent highly virulent bovine viral diarrhea virus isolates from a 2013 series of outbreaks. We discovered a unique special feature of the viral genome, an unstable duplication of 222 nucleotides which is eventually deleted by viral polymerase activity, leading to an unexpectedly mixed population of viral genomes for all investigated isolates. Our study is of high importance to the field because we demonstrate that these insertion/deletion events allow another level of genome plasticity of plus-strand RNA viruses, in addition to the well-known polymerase-induced single nucleotide variations which are generally considered the main basis for viral adaptation and evolution.

Induction of interferon-gamma and downstream pathways during establishment of fetal persistent infection with bovine viral diarrhea virus

Development of transplacental infection depends on the ability of the virus to cross the placenta and replicate within the fetus while counteracting maternal and fetal immune responses. Unfortunately, little is known about this complex process. Non-cytopathic (ncp) strains of bovine viral diarrhea virus (BVDV), a pestivirus in the Flaviviridae family, cause persistent infection in early gestational fetuses (<150 days; persistently infected, PI), but are cleared by immunocompetent animals and late gestational fetuses (>150 days; transiently infected, TI). Evasion of innate immune response and development of immunotolerance to ncp BVDV have been suggested as possible mechanisms for the establishment of the persistent infection. Previously we have observed a robust temporal induction of interferon (IFN) type I (innate immune response) and upregulation of IFN stimulated genes (ISGs) in BVDV TI fetuses. Modest chronic upregulation of ISGs in PI fetuses and calves reflects a stimulated innate immune response during persistent BVDV infection. We hypothesized that establishing persistent fetal BVDV infection is also accompanied by the induction of IFN-gamma (IFN-γ). The aims of the present study were to determine IFN-γ concentration in blood and amniotic fluid from control, TI and PI fetuses during BVDV infection and analyze induction of the IFN-γ downstream pathways in fetal lymphoid tissues. Two experiments with in vivo BVDV infections were completed. In Experiment 1, pregnant heifers were infected with ncp BVDV type 2 on day 75 or 175 of gestation or kept naïve to generate PI, TI and control fetuses, respectively. Fetuses were collected by Cesarean section on day 190. In Experiment 2, fetuses were collected on days 82, 89, 97, 192 and 245 following infection of pregnant heifers on day 75 of gestation. The results were consistent with the hypothesis that ncp BVDV infection induces IFN-γ secretion during acute infection in both TI and PI fetuses and that lymphoid tissues such as spleen, liver and thymus, serve both as possible sources of IFN-γ and target organs for its effects. Notably, induction of IFN-γ coincides with a decrease in BVDV RNA concentrations in PI fetal blood and tissues. This is the first report indicating the possible presence of an adaptive immune response in persistent BVDV infections, which may be contributing to the observed reduction of viremia in PI fetuses.

BLOOD COLLECTED ON FILTER PAPER FOR WILDLIFE SEROLOGY: EVALUATING STORAGE AND TEMPERATURE CHALLENGES OF FIELD COLLECTIONS

Filter-paper (FP) blood sampling can facilitate wildlife research and expand disease surveillance. Previous work indicated that Nobuto FP samples from caribou and reindeer (Rangifer tarandus subspecies) had comparable sensitivity and specificity to serum samples (≥ 80% for both) in competitive enzyme-linked immunosorbent assays (cELISAs) for Brucella spp., Neospora caninum, and West Nile virus. The same sensitivity and specificity criteria were met in indirect ELISAs for Brucella spp., bovine herpesvirus type 1 (BHV-1), parainfluenza virus type 3 (PI-3), and bovine respiratory syncytial virus (BRSV), with adjusted FP thresholds used for PI-3 and BRSV. Comparable sensitivity and specificity values to serum were also observed for FP in virus neutralization (VN) assays for bovine viral diarrhea virus types I and II; however, reduced sensitivity is a potential limitation of FP samples in protocols that require undiluted serum (i.e., VN and N. caninum cELISA). We evaluated the performance of FP samples from reindeer and caribou in these nine assays after simulating potential challenges of high-latitude field collections: 1) different durations of storage and 2) different processing/storage regimes involving freezing or drying. Sample pairs (serum and FP) were collected from reindeer and caribou populations in 2007-10 and were tested in duplicate. Comparable performance to serum was defined as sensitivity and specificity ≥ 80%. In the storage experiments, FP performance was determined after 2 mo of storage dry at room temperature, and after two longer periods (variable depending on assay; up to 2 yr). After 1 yr, compared to frozen serum stored for the same period, sensitivity was ≥ 88% for all but two assays (68% BHV-1; 75% PI-3), and specificity remained >90%. A limited trial evaluated the effect of freezing FP samples as opposed to drying them for storage. There were no observed detrimental effects of freezing on FP sample performance, but rigorous investigation is warranted.

BLOOD COLLECTED ON FILTER PAPER FOR WILDLIFE SEROLOGY: DETECTING ANTIBODIES TONEOSPORA CANINUM, WEST NILE VIRUS, AND FIVE BOVINE VIRUSES IN REINDEER

We compared Nobuto filter paper (FP) whole-blood samples to serum for detecting antibodies to seven pathogens in reindeer (Rangifer tarandus tarandus). Serum and FP samples were collected from captive reindeer in 2008-2009. Sample pairs (serum and FP eluates) were assayed in duplicate at diagnostic laboratories with the use of competitive enzyme-linked immunosorbent assays (cELISAs) for Neospora caninum and West Nile virus (WNV); indirect ELISA (iELISAs) for bovine herpesvirus type 1 (BHV-1), parainfluenza virus type 3 (PI-3), and bovine respiratory syncytial virus (BRSV); and virus neutralization (VN) for bovine viral diarrhea virus (BVDV) types I and II. Assay thresholds were evidence-based values employed by each laboratory. Comparable performance to serum was defined as FP sensitivity and specificity ≥ 80%. Filter-paper specificity estimates ranged from 92% in the cELISAs for N. caninum and WNV to 98% in the iELISAs for PI-3 and BRSV. Sensitivity was >85% for five tests (most ≥ 95%) but was insufficient (71-82%) for the PI-3 and BRSV iELISAs. Lowering the threshold for FP samples in these two ELISAs raised sensitivity to ≥ 87% and reduced specificity slightly (≥ 90% in three of the four test runs). Sample size limited the precision of some performance estimates. Based on the criteria of sensitivity and specificity ≥ 80%, and using adjusted FP thresholds for PI-3 and BRSV, FP sensitivity and specificity were comparable to serum in all seven assays. A potential limitation of FP is reduced sensitivity in tests that require undiluted serum (i.e., N. caninum cELISA and BVDV VNs). Possible toxicity to the assay cell layer in VN requires investigation. Results suggested that cELISA is superior to iELISA for detecting antibodies in FP samples from reindeer and other Rangifer tarandus subspecies. Our findings expand the potential utility of FP sampling from wildlife.

A bovine viral diarrhea virus type 1a strain in China: isolation, identification, and experimental infection in calves

BackgroundBovine viral diarrhea virus (BVDV) is one of the most important pathogens in cattle. Previously, BVDV sub-genotypes of 1b, 1c, 1d, and 1 m were detected in China. However, isolation of BVDV type 1a from cattle has not been reported in China. In 2010, twenty nasal swabs and blood samples were collected from the cattle suspected BVDV infection in Henan province, China. A BVDV isolate was isolated using cell culture, and the pathogenesis of the virus isolate was studied.MethodsVirus isolation was performed on MDBK cells. The virus identification was conducted by RT-PCR, neutralization test and immunofluorescence assay. In order to determine the genotype of the newly isolated virus, the 5′ un-translated region (5′UTR) of the virus isolate was cloned, sequenced and phylogenetically analyzed. To evaluate the virulence of the virus isolate, four BVDV sero-negative calves were intranasally inoculated with the virus suspension. Rectal temperatures and clinical signs were recorded daily. Blood samples were analyzed for changes in white blood cell counts, and tissue samples were taken for histopathology analysis.ResultsA new isolate of bovine viral diarrhea virus (BVDV), named HN01, was isolated from the nasal swabs using MDBK cell culture. The HN01 strain caused cytopathic effect (CPE) in MDBK cell cultures after two passages. The virus specifically reacted to BVDV1-specific monoclonal antibody in an immunofluorescence assay. A fragment of 288 bp of genome from this isolate was amplified by the RT-PCR. Phylogenetic analysis of 5′UTR indicated that the virus was BVDV 1a. In the pathogenesis study, four calves experimentally infected with the BVDV strain developed depression, cough and other clinical signs. Calves showed high temperature over 40°C, and white blood cell counts dropped more than 40%.ConclusionsA new subgenotype 1a strain of BVDV was firstly isolated from dairy cattle in China. The experimental infection showed that the virus was moderate pathogenic to cattle and can be used as a BVDV challenge virus to evaluate the efficacy of BVDV vaccines in the target animals.

Camelids as a host of bovine viral diarrhoea virus infection — what we have learned to date

Bovine viral diarrhoea virus (BVDV) has been associated with reproductive loss, diarrhoea, immune-suppression with increased susceptibility to opportunistic infection (such as parasitism and pneumonia), wastage and death in South American Camelids (SAC). Unidentified BVDV infection thus poses a significant threat to herd health. BVDV type 1b strains predominate in alpacas and are able to establish transplacental infection, potentially leading to persistently infected (PI) offspring in &gt;80% of naive, pregnant alpacas naturally exposed to BVDV type Ib during early gestation. PI alpaca crias experience a high degree of morbidity and mortality in the first 6 months of life, associated with a variety of clinical disease manifestations. Peripartum phenotypic and haematological characteristics of PI crias may be clinically indistinguishable from those of chronically infected crias with extended viraemia. Low birth weight, stunted growth, anaemia, relative and absolute monocytosis are commonly observed in affected animals. PI crias may have host defense deficits similar to PI calves and experience widespread viral tissue distribution. Both clinical and epidemiological studies underscore the importance of routine BVDV-specific diagnostic testing in order to identify persistently (lifelong) and chronically infected camelids, which serve as an important source of viral spread within and between farms.

Npro of Bungowannah virus exhibits the same antagonistic function in the IFN induction pathway than that of other classical pestiviruses

Bungowannah virus is the most divergent atypical pestivirus that had been detected up to now, and does not fit into any of the four approved species: Bovine viral diarrhea virus type 1 (BVDV-1) and type 2 (BVDV-2), Classical swine fever virus (CSFV) and Border disease virus (BDV). However, the presence of Npro and Erns coding regions, which are unique to pestiviruses, provides clear evidence of a pestivirus. Nevertheless, the amino acid identity of Bungowannah virus Npro and BVDV-1 Npro (strain CP7) is only 51.5%. By using a BVDV-1 backbone, a novel chimeric construct was generated, in which the genomic region encoding the non-structural protein Npro was replaced by that of Bungowannah virus (CP7_Npro-Bungo). In vitro studies of CP7_Npro-Bungo revealed autonomous replication with the same efficacy as the BVDV backbone CP7 and infectious high-titer virus could be collected. In order to compare the ability of interferon (IFN) suppression, two reporter gene assays, specific for type-I IFN, were carried out. In virus-infected cells, no significant difference in blocking of IFN expression between the parental virus CP7, Bungowannah virus and the chimeric construct CP7_Npro-Bungo could be detected. In contrast, an Npro deletion mutant showed an impaired replication in bovine cells and a marked type-I IFN response.Taken together, our findings reveal the compatibility of non-structural protein Npro of atypical Bungowannah virus with a BVDV type 1 backbone and its characteristic feature as an inhibitor of type-I IFN induction with an inhibitor-activity comparable to other pestiviruses.

Characterization of genotypes among bovine viral diarrhea virus type 1 strains according to palindromic nucleotide substitutions in the genomic 5′-untranslated region

Two-hundred and eighty-one strains of bovine viral diarrhea virus type 1 (BVDV-1) were evaluated according to the palindromic nucleotide substitutions (PNS) method, a simple and practical genotyping procedure, at the three variable loci, V1, V2 and V3, in the 5′-untranslated region of genomic RNA. Ten PNSs were characteristic to the Pestivirus genus, located in the V1 and V2 loci. The BVDV-1 species shared a U-A pairing, a species-characteristic PNS, in position fifteen common to the V1 locus, and a G-C pairing in position five common to the V2 and V3 loci. Within the BVDV-1 species, 15 genotypes, BVDV-1a, BVDV-1b, BVDV-1c, BVDV-1d, and the newly described from BVDV-1e to BVDV-1o were identified based on characteristic nucleotide base pairings. The nomenclature reflected the genotypes’ level of divergence within the species. Genotypes BVDV-1l, BVDV-1m and BVDV-1o were borderline in the species.

Evaluation of response to bovine viral diarrhea virus type 2 vaccination and timing of weaning on yearling ultrasound body composition, performance, and carcass quality traits in Angus calves1,2,3

There are concerns about antagonisms between immunity and animal productivity in livestock production. The objective of this study was to evaluate the effect of antibody levels through a response to vaccination protocol, weaning timing, and their interaction on performance and carcass quality traits in Angus beef cattle. Final antibody level and response to vaccination were based on neutralizing serum antibodies against bovine viral diarrhea virus type 2 (BVDV2). Calves were followed through development and the feedlot phase, with collection of yearling ultrasound (n=957), preharvest (n=762), and carcass (n=673) data. In this study, 48% of the animals were observed to have positively responded to the vaccine, as evidenced by higher final antibody levels compared to prevaccination antibody levels. Increased final antibody levels were significantly (P<0.05) associated with increased yearling weight and increased subcutaneous fat over the rump. An interaction between final antibody level and weaning time also was associated (P<0.05) with Warner-Bratzler shear force (WBSF) and meat pH, with a favorable, negative relationship between final antibody and WBSF in calves weaned at initial vaccination. Overall antibody response by wean time interaction had a significant (P<0.05) association with ADG and meat pH, with calves weaned at initial vaccination having a favorable, positive relationship between overall antibody response and ADG. Under both the final antibody and overall antibody response models, animals weaned at initial vaccination had significantly (P<0.05) lower intramuscular fat at yearling time and conversely higher harvest weight than animals weaned at the booster vaccination. When antibody response was grouped (none, low, high), a significant interaction (P<0.05) between antibody response group and weaning time was identified for ADG, harvest weight, and HCW. Animals weaned at the initial vaccination in the high antibody response group had the advantage for ADG, harvest weight, and HCW compared to animals in the high-response group that were weaned at booster vaccination. Linear increases in antibody response generally did not have negative effects on performance or carcass quality traits in finished cattle (P>0.05). Therefore, producers should not be concerned about decreased production or quality attributes as a result of developing a robust antibody response to vaccination for BVDV2 in beef cattle.

A study of the effectiveness of a needle-free injection device compared with a needle and syringe used to vaccinate calves against bovine viral diarrhea and infectious bovine rhinotracheitis viruses

The aim of this study was to compare the effectiveness of a needle-free injection device (NF) with a needle and syringe (NS) when used to vaccinate calves against bovine viral diarrhea virus (BVDV) and infectious bovine rhinotracheitis virus (IBRV). The study was conducted in two independent phases. Ninety-six crossbred beef calves were vaccinated in the spring and 98 beef calves in the autumn. The calves were vaccinated using a NF or NS at 2months of age (day 0) and again on day 119, with a modified-live virus vaccine containing IBRV, BVDV (types 1 and 2), parainfluenza-3 virus, and bovine respiratory syncytial virus. In each herd 10 calves were left unvaccinated to determine whether exposure to either BVDV or IBRV occurred.Visible vaccine residue at the surface of the skin/hair was apparent immediately following vaccination with NF in 30% of the spring-born calves following both the primary and booster vaccination. In the autumn, visible vaccine residues occurred in 19% and 8% of NF-vaccinated calves following the primary and booster vaccination. Post-vaccination skin reactions recorded on days 21, 42, 119 and 140 occurred with greater frequency in NF-vaccinated calves than NS-vaccinated ones.Blood samples were collected on days 0, 21, 42, 119, and 140 and tested for antibodies to BVDV and IBRV. Vaccination technique had no significant effect on BVDV or IBRV antibody concentrations at any time point. NF was as effective as NS vaccination in eliciting BVDV and IBRV antibody responses.

An ultra-sensitive detection of a whole virus using dual aptamers developed by immobilization-free screening

In this study, we successfully developed a ssDNA aptamer pairs by using an advanced immobilization-free SELEX method with affinity-based selection and counter-screening process at every round. By implementing this method, two different aptamers specifically binding to bovine viral diarrhea virus type 1(BVDV type 1) with high affinity were successfully screened. This aptamer pair was applied to ultrasensitive detection platform for BVDV type 1 in a sandwich manner. The ultrasensitive detection of BVDV type 1 using one of aptamers conjugated with gold nanoparticles was obtained in aptamer–aptamer sandwich type sensing format, with the limit of detection of 800copies/ml, which is comparable to a real-time PCR method.

An evaluation of circulating bovine viral diarrhea virus type 2 maternal antibody level and response to vaccination in Angus calves1,2,3,4

Vaccination against viruses has been shown to help prevent bovine respiratory disease in cattle. However, both passively acquired maternal antibody concentration and calf age have been shown to impact the ability of the immune system of a calf to respond to vaccination. The objectives of this study were to identify and evaluate environmental and management factors that affect 1) passively acquired bovine viral diarrhea virus (BVDV) type 2 antibody level, 2) decay rate of passively acquired BVDV type 2 antibody level, and 3) responses to BVDV type 2 vaccinations. A 2-shot modified live vaccine was administered to 1,004 Angus calves that were weaned at either the initial vaccination (n = 508) or the booster vaccination (n = 496). Calves weaned at the initial vaccination averaged 139 d whereas calves weaned at booster vaccination averaged 128 d of age. Bovine viral diarrhea virus type 2 antibodies were measured in 3 approximately 21-d intervals, serially collected serum samples to quantify antibody levels at initiation and end of vaccination protocol in addition to responses to initial, booster, and overall vaccination protocol. Amount of passively transferred antibody in the calf increased as dam age increased from 2 to 6 yr (P < 0.05) with no differences after dams reached 6 yr (P > 0.05). Calf age nested within birth year-season and dam age affected both initial and final antibody level, initial response, booster response, and overall antibody response to vaccination. The level of circulating, passively acquired maternal antibodies present at the time of vaccination had a significant (P < 0.05) negative effect on antibody responses to vaccination (initial response, booster response, and overall response). Calves that were weaned at the time of initial vaccination had significantly (P < 0.05) greater final antibody level, initial response, and overall response to vaccination than animals weaned at booster vaccination. In order for a calf to mount an overall antibody response to vaccination, maternal antibodies in circulation need to be less than 3.12 titers. However, the age at which a calf reached this antibody threshold was dependent on dam age. This information will help cattle managers and consultants design vaccination protocols to successfully mount an antibody response to vaccination.

Preliminary mapping of non-conserved epitopes on envelope glycoprotein E2 of Bovine viral diarrhea virus type 1 and 2

Bovine viral diarrhea virus (BVDV) belongs together with Classical swine fever virus (CSFV) and Border disease virus (BDV) to the genus Pestivirus in the Flaviviridae family. BVDV has been subdivided into two different species, BVDV1 and BVDV2 based on phylogenetic analysis. Subsequent characterization of both strains revealed major antigenic differences. Because the envelope glycoprotein E2 is the most immunodominant protein for all pestiviruses, the present study focused on epitope mapping by constructing chimeric BVDV type 1 and 2 E2 genes in expression plasmids. These plasmids with chimeric E2-genes were transfected in SK6 cells and transient expression was studied by immunostaining with a panel of MAbs specific for E2 of BVDV1 or BVDV2, resulting in the localization of type-specific antigenic domains at similar regions. These results indicate that E2 glycoproteins of both BVDV types exhibit a comparable antigenic structure, but with type specific epitopes. In addition, the antigenic resemblance with envelope glycoprotein E2 of Classical swine fever virus is discussed.

Protection against bovine herpesvirus type 1 (BHV-1) abortion following challenge 8 months or approximately 1 year after vaccination

Bovine herpesvirus type 1 (BHV-1) is a major cause of reproductive failure. A study was conducted to determine if vaccination with a modified-live virus (MLV) vaccine containing BHV-1 at either 8 or 13 months prior to challenge protects against BHV-1 challenge-induced abortion. A total of 51 beef heifers, seronegative to bovine viral diarrhea virus types 1 and 2 and BHV-1, were vaccinated subcutaneously with a commercially available combination MLV vaccine containing BHV-1 and inactivated bacterin vaccine, or placebo containing bacterin only. The estrus cycle was synchronized and heifers wereartificially inseminated approximately 6 or 1 month(s) after vaccination. Heifers were challenge-inoculated intravenously at approximately 193 days of gestation with a virulent BHV-1 virus. Clinical signs of BHV-1 infection were monitored for 14 days following challenge. Serological status and occurrence of abortion or stillbirth were also determined. Tissues collected from aborted fetuses (n = 22) and full-term calves that were born dead (i.e., stillbirth [n = 1] or dystocia [n = 2]) were tested for BHV-1 via virus isolation. BHV-1 was isolated from 1 fetus (7.7%) from Treatment Group 1 heifers (TGl -heifers challenged 13 months after BHV-1 MLV vaccination), from 3 fetuses/calves (15.8%) from Treatment Group 2 heifers (TG2 - heifers challenged 8 months after BHV-1 MLV v~ccination), and from 7 fetuses (36.8%) from Treatment Group 3 heifers (TG3 - control heifers that rec~ived bacterin only). Polymerase chain reaction testing results indicated that 1 fetus from the 13 (7. 7%) TG 1 heifers, 5 fetuses out of the 19 (26.3%) TG2 heifers, and 18 fetuses out of the 19 (94.7%) TG3 control heifers were BHV-1 positive. In this study, a combination MLV vaccine containing BHV-1 administered 8 or 13 months prior to challenge provided a significant level of protection against fetal infection in the face of a substantial challenge infection with BHV-1 when compared to nonvaccinated controls.

Spontane bloedingen bij een pasgeboren kalf met persisterende BVDV1b-infectie

Een kalf vertoonde op zijn tweede levensdag huidbloedingen en werd doorverwezen naar de kliniekonder verdenking van boviene neonatale pancytopenie (BNP). Hematologisch onderzoek toonde extremetrombocytopenie, matige anemie, maar geen leukopenie aan. Een PCR-test op gehepariniseerd bloed waspositief voor het boviene virale diarreevirus (BVDV), net als bij twee BVDV-antigeen ELISA’s op bloeddie drie en tien weken later genomen werden. Niet-cytopathogeen BVDV-type 1b werd geïsoleerd uit hetbloed. Alhoewel het kalf herstelde van de bloedingen en gezond bleef, werd het wegens de persisterendeBVDV-infectie geëuthanaseerd op de leeftijd van elf weken. Op basis van de anamnese kon BNPuitgesloten worden uit de differentiaaldiagnose. Deze casus toont aan dat het bloedingssyndroom nietuitsluitend het gevolg is van besmetting met BVDV-type 2 en dat de klinische verschijnselen bij metBVDV1b besmette neonatale kalveren identiek kunnen zijn aan deze bij BNP.

Vaccination with a multivalent modified-live virus vaccine administered one year prior to challenge with bovine viral diarrhea virus type 1b and 2a in pregnant heifers

A total of 85 beef heifers were used to determine if vaccination with a modified-live virus (MLV) vaccine containing bovine viral diarrhea virus types 1 and 2 (BVDV1 and BVDV2) approximately 1 year prior to challenge with virulent BVDVlb and BVDV2a will protect against fetal infection. BVDV1 and BVDV2 seronegative heifers were vaccinated at approximately 15 months of age with a commercially available combination MLV vaccine containing BVDVla and BVDV2a or placebo; heifers were artificially inseminated approximately 9 months after vaccination. The heifers were challenge- inoculated intranasally at 80 to 90 days of gestation with a virulent BVDVlb or BVDV2a virus (i.e., 368 and 374 days post-vaccination, respectively). Clinical signs of BVDV infection including serologic status, complete blood count, rectal temperature, and viremia were monitored for 14 days following challenge. After challenge, vaccinated heifers in the BVDVlb and BVDV2a challenge groups experienced significantly less leukopenia and viremia than control heifers. Fetuses were harvested approximately 70 days following challenge and tissues were collected for virus isolation. All heifers that received vaccine were protected from fetal infection following challenge with BVDVlb or BVDV2a, whereas 15 of 18 (83.3%) and 21 of22 (95.5%) control heifers had infected BVDVlb and BVDV2a fetuses, respectively. In this study, a combination MLV vaccine containing the minimum immunizing dose of BVDVla and BVDV2a, with other fractions at release dose or higher, administered 1 year prior to challenge protected against fetal infection in the face of a substantial challenge infection with either BVDVlb or BVDV2a.