Evaluation of the Mucosal Immunity Effect of Bovine Viral Diarrhea Virus Subunit Vaccine E2Fc and E2Ft.

Classified as a class B infectious disease by the World Organization for Animal Health (OIE), bovine viral diarrhea/mucosal disease is an acute, highly contagious disease caused by the bovine viral diarrhea virus (BVDV). Sporadic endemics of BVDV often lead to huge economic losses to the dairy and beef industries. To shed light on the prevention and control of BVDV, we developed two novel subunit vaccines by expressing bovine viral diarrhea virus E2 fusion recombinant proteins (E2Fc and E2Ft) through suspended HEK293 cells. We also evaluated the immune effects of the vaccines. The results showed that both subunit vaccines induced an intense mucosal immune response in calves. Mechanistically, E2Fc bonded to the Fc γ receptor (FcγRI) on antigen-presenting cells (APCs) and promoted IgA secretion, leading to a stronger T-cell immune response (Th1 type). The neutralizing antibody titer stimulated by the mucosal-immunized E2Fc subunit vaccine reached 1:64, which was higher than that of the E2Ft subunit vaccine and that of the intramuscular inactivated vaccine. The two novel subunit vaccines for mucosal immunity developed in this study, E2Fc and E2Ft, can be further used as new strategies to control BVDV by enhancing cellular and humoral immunity.

Do modified live virus vaccines against bovine viral diarrhea induce fetal cross-protection against HoBi-like Pestivirus?

Bovine Pestivirus heterogeneity is a major challenge for vaccines against bovine viral diarrhea (BVD). In breeding herds, fetal protection is a high priority issue. To some degree, fetal infections in vaccinated heifers have been attributed to the antigenic diversity of bovine Pestiviruses. The purpose of this study was to assess fetal protection against a divergent bovine Pestivirus (Hobi-like Pestivirus, HoBiPeV) with a commercially available modified live vaccine (MLV) claiming fetal protection against BVDV 1 and BVDV 2 up to one year after the first inoculation. Five vaccinated and four unvaccinated heifers were challenged by intranasal inoculation with the HoBiPeV Italy-1/10-1 strain between 82 and 89 days after insemination, i.e. between 4 and 6 months after vaccination. At challenge, neutralizing antibody titers to HoBiPeV in vaccinated heifers were low or even undetectable. Of the four unvaccinated heifers, one control animal aborted (fetus not available) and the remaining three gave birth to HoBiPeV positive calves. Among the heifers of the vaccinated group, one aborted the fetus in the sixth month of pregnancy, which tested Pestivirus negative, while three others gave birth to healthy, HoBiPeV negative calves; the remaining heifer delivered one HoBiPeV positive calf. The results suggest that the BVDV vaccine might be able to elicit a partial fetal protection against HobiPeV, even in absence of a strong specific antibody response.

Detection and genotyping of bovine viral diarrhea virus found contaminating commercial veterinary vaccines, cell lines, and fetal bovine serum lots originating in Mexico.

In this communication, we report the presence of RNA of bovine viral diarrhea virus (BVDV) as a contaminant of different biological products used in Mexico for veterinary vaccine production. For this purpose, six batches of monovalent vaccines, eight cell line batches used for vaccine production, and 10 fetal bovine serum lots (FBS) commercially available in Mexico from different suppliers were tested by reverse transcription polymerase chain reaction (RT-PCR). Viral RNA was detected in 62.5% of the samples analyzed. Phylogenetic analysis revealed the presence of the subgenotypes BVDV-1a, 1b, and BVDV-2a in the tested samples. Collectively, these findings indicate that contamination by BVDV RNA occurs in commercial vaccines and reagents used in research and production of biological products. The ramifications of this contamination are discussed.

Serological evidence of Coxiella burnetii, Leptospira interrogans Hardjo, Neospora caninum and bovine pestivirus infections in a dairy cattle herd from the United Arab Emirates.

The serostatus of five abortigenic agents and the association between abortion history and Coxiella burnetii seropositivity were assessed in 350 dairy cattle from Al Ain, UAE. The bovine sera were ELISA-screened for C. burnetii, Leptospira Hardjo, Neospora caninum, and Brucella abortus antibodies, plus bovine pestivirus (BVDV) antigen. The serology data were collated and the level of significance between the proportions of C. burnetii-seropositive cattle with and without abortion history assessed by the Z test of two proportions. Of the 350 cattle, 41.4%, 1.7%, 1.4%, 0.3%, and 0.0% were seropositive to the above pathogens, respectively. Besides, 61.9%, 2.9%, 1.0%, 0.0%, and 0.0% of the 105 cattle with history of abortion and 32.7%, 1.2%, 1.6%, 0.0% and 0.0% of the 245 seropositive cattle with no history of abortion were also seropositive for the above pathogens respectively. Moreover, the proportion of C. burnetii-seropositive cattle with history of abortion were significantly higher than the C. burnetii-seropositive ones without abortion history (p-value < 0.01). Apparent C. burnetii infections were relatively higher than the other four pathogens suggesting this bacterium contributed to abortion in the herd. Additional research on the public and bovine health implications of C. burnetii and Leptospira in the UAE are urgently needed.

Estimation of the within-herd transmission rates of bovine viral diarrhoea virus in extensively grazed beef cattle herds.

Many research groups have developed mathematical models to simulate the dynamics of BVDV infections in cattle herds. However, most models use estimates for within-herd BVDV transmission rates that are either based on expert opinion or adapted from other dairy herd simulation models presented in the literature. There is currently little information on the transmission rates for BVDV in extensively grazed beef herds partly due to the logistical challenges in obtaining longitudinal data of individual animal's seroconversion, and it may not be appropriate to apply the same transmission rates from intensive dairy herds given the significant differences in herd demographics and management. To address this knowledge gap, we measured BVDV antibody levels in 15 replacement heifers in each of 75 New Zealand beef breeding farms after their first calving and again at pregnancy scanning or weaning to check for seroconversion. Among these, data from 9 farms were used to infer the within-herd BVDV transmission rate with an approximate Bayesian computation method. The most probable within-herd BVDV transmission rate was estimated as 0.11 per persistently infected (PI) animal per day with a 95% highest posterior density interval between 0.03 and 0.34. This suggests that BVDV transmission in extensively grazed beef herds is generally slower than in dairy herds where the transmission rate has been estimated at 0.50 per PI animal per day and therefore may not be sufficient to ensure that all susceptible breeding females gain adequate immunity to the virus before the risk period of early pregnancy for generating new PI calves.

Detection of bovine pestiviruses in sera of beef calves by a RT-PCR based on a newly designed set of pan-bovine pestivirus primers.

The pestiviruses bovine viral diarrhea virus 1 and 2 (BVDV-1 and -2, respectively) and HoBi-like pestivirus (HoBiPeV) are important pathogens of cattle, and a number of reverse-transcription PCR (RT-PCR)-based assays have been developed for their detection in clinical specimens. We evaluated a newly designed set of pan-bovine pestivirus primers (BP189-389) in a gel-based RT-PCR screening test for pestiviruses in the sera of beef calves destined for export from southern Brazil. Serum samples positive for BVDV antigens by an antigen ELISA ( n = 135) were submitted to RT-PCR assays using different sets of primers, followed by nucleotide sequencing of the amplicons. RT-PCR with pestivirus primers 324-326 detected 110 positive samples: BVDV-1 ( n = 62), BVDV-2 ( n = 38), and HoBiPeV ( n = 10). A PCR using primers HCV90-368 detected 97 positive samples (64 BVDV-1; 33 BVDV-2). An additional RT-PCR round using BVDV-2-specific primers (2F-2R) detected 45 positive samples (including 38 detected by primers 324-326 and 33 by HCV90-368); whereas a RT-PCR using HoBiPeV-specific primers (N2-R5) detected 26 positive samples (including 10 detected by primers 324-326).The assay using the primers BP189-389 detected all 135 ELISA-positive samples, including the 26 HoBiPeV detected by primers N2-R5. Our results demonstrated that primers BP189-389 compare favorably against other primer sets in the detection of bovine pestiviruses, especially HoBiPeV. This conventional PCR may be useful for efficient detection of pestiviruses in bovine sera and other specimens as well, especially in laboratories without real-time PCR equipment.

Global knowledge gaps in the prevention and control of bovine viral diarrhoea (BVD) virus.

The significant economic impacts of bovine viral diarrhoea (BVD) virus have prompted many countries worldwide to embark on regional or national BVD eradication programmes. Unlike other infectious diseases, BVD control is highly feasible in cattle production systems because the pathogenesis is well understood and there are effective tools to break the disease transmission cycle at the farm and industry levels. Coordinated control approaches typically involve directly testing populations for virus or serological screening of cattle herds to identify those with recent exposure to BVD, testing individual animals within affected herds to identify and eliminate persistently infected (PI) cattle, and implementing biosecurity measures such as double-fencing shared farm boundaries, vaccinating susceptible breeding cattle, improving visitor and equipment hygiene practices, and maintaining closed herds to prevent further disease transmission. As highlighted by the recent DISCONTOOLS review conducted by a panel of internationally recognized experts, knowledge gaps in the control measures are primarily centred around the practical application of existing tools rather than the need for creation of new tools. Further research is required to: (a) determine the most cost effective and socially acceptable means of applying BVD control measures in different cattle production systems; (b) identify the most effective ways to build widespread support for implementing BVD control measures from the bottom-up through farmer engagement and from the top-down through national policy; and (c) to develop strategies to prevent the reintroduction of BVD into disease-free regions by managing the risks associated with the movements of animals, personnel and equipment. Stronger collaboration between epidemiologists, economists and social scientists will be essential for progressing efforts to eradicate BVD from more countries worldwide.

Experimental infection of mice with noncytopathic bovine viral diarrhea virus 2 increases the number of megakaryocytes in bone marrow.

BACKGROUND: Bovine viral diarrhea virus (BVDV) causes significant economic losses worldwide in the cattle industry through decrease in productive performance and immunosuppression of animals in herds. Recent studies conducted by our group showed that mice can be infected with BVDV-1 by the oral route. The purpose of this study was to assess the clinical signs, hematological changes, histopathological lesions in lymphoid tissues, and the distribution of the viral antigen after oral inoculation with a Korean noncytopathic (ncp) BVDV-2 field isolate in mice. METHODS: Mice were orally administered a low or high dose of BVDV-2; blood and tissue samples were collected on days 2, 5, and 9 postinfection (pi). We monitored clinical signs, hematological changes, histopathological lesions, and tissue distribution of a viral antigen by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC) and then compared these parameters with those in ncp BVDV-1 infections. RESULTS: None of the infected mice developed any clinical signs of the illness. Significant thrombocytopenia was found in both low- and high-dose-inoculated mice on day 2 pi. Leukopenia was apparent only in low-dose-inoculated mice on day 2 pi, whereas lymphopenia was not observed in any ncp BVDV-2-infected animal. Viral RNA was found in the spleen in of low- and high-dose-inoculated mice by RT-PCR. According to the results of IHC, the viral antigen was consistently detected in lymphocytes of bone marrow and spleen and less frequently in bronchus-associated lymphoid tissue (BALT), mesenteric lymph nodes, and Peyer's patches. Despite the antigen detection in BALT and mesenteric lymph nodes, histopathological lesions were not observed in these tissues. Lympholysis, infiltration by inflammatory cells, and increased numbers of megakaryocytes were seen in Peyer's patches, spleens, and bone marrow, respectively. In contrast to ncp BVDV-1 infection, lympholysis was found in the spleen of ncp BVDV-2-infected mice. These histopathological lesions were more severe in high-dose-inoculated mice than in low-dose-inoculated mice. CONCLUSIONS: Our results provide insight into the pathogenesis of ncp BVDV-2 infection in mice. Collectively, these results highlight significant differences in pathogenesis between ncp BVDV-1 and ncp BVDV-2 infections in a murine model.

A systematic worldwide review of the direct monetary losses in cattle due to bovine viral diarrhoea virus infection.

Bovine viral diarrhoea virus (BVDV) is an important infectious agent of cattle worldwide that affects herd productivity and reproduction. In this systematic review of the impact of BVDV, studies were analysed with a particular focus on the monetary implications and types of direct losses, the initial infection status of herds, production systems, time periods of assessment, calculation level, study types and whether or not country-specific assessments were published. A linear mixed model was applied to analyse factors that influence the level of monetary direct losses due to BVDV infection. The 44 studies included in this review covered 15 countries and assessed direct monetary losses due to BVDV incurred over the past 30 years. Direct losses between and within countries were largely heterogeneous with respect to the monetary level and types of direct losses, ranging from 0.50 to 687.80 US dollars (USD) per animal.1 Average direct losses per naïve dairy cow were USD24.85 higher than per beef cow. Country-specific assessments of direct losses due to BVDV were provided in 38/44 (86.4%) studies. Mortality, morbidity, premature culling, stillbirths, abortion, reinfection, country and study type had a significant influence on the monetary level of direct losses (r2 = 0.69). Countries recording direct losses were more likely to carry out voluntary or compulsory control and eradication programmes (odds ratio = 10.2; 95% confidence interval 1.7-81.9; P = 0.004).

Molecular Characterization of a Novel Bovine Viral Diarrhea Virus Isolate SD-15.

As one of the major pathogens, bovine viral diarrhea virus caused a significant economic loss to the livestock industry worldwide. Although BVDV infections have increasingly been reported in China in recent years, the molecular aspects of those BVDV strains were barely characterized. In this study, we reported the identification and characterization of a novel BVDV isolate designated as SD-15 from cattle, which is associated with an outbreak characterized by severe hemorrhagic and mucous diarrhea with high morbidity and mortality in Shandong, China. SD-15 was revealed to be a noncytopathic BVDV, and has a complete genomic sequence of 12,285 nucleotides that contains a large open reading frame encoding 3900 amino acids. Alignment analysis showed that SD-15 has 93.8% nucleotide sequence identity with BVDV ZM-95 isolate, a previous BVDV strain isolated from pigs manifesting clinical signs and lesions resembling to classical swine fever. Phylogenetic analysis clustered SD-15 to a BVDV-1m subgenotype. Analysis of the deduced amino acid sequence of glycoproteins revealed that E2 has several highly conserved and variable regions within BVDV-1 genotypes. An additional N-glycosylation site (240NTT) was revealed exclusively in SD-15-encoded E2 in addition to four potential glycosylation sites (Asn-X-Ser/Thr) shared by all BVDV-1 genotypes. Furthermore, unique amino acid and linear epitope mutations were revealed in SD-15-encoded Erns glycoprotein compared with known BVDV-1 genotype. In conclusion, we have isolated a noncytopathic BVDV-1m strain that is associated with a disease characterized by high morbidity and mortality, revealed the complete genome sequence of the first BVDV-1m virus originated from cattle, and found a unique glycosylation site in E2 and a linear epitope mutation in Erns encoded by SD-15 strain. Those results will broaden the current understanding of BVDV infection and lay a basis for future investigation on SD-15-related pathogenesis.

[PESTIVIRUSES IN RUMINANTS].

The genus Pestivirus includes four species: bovine viral diarrhea virus 1, bovine viral diarrhea virus 2, classical swine fever disease virus, and ovine border disease virus. Pestiviruses infect many species of domestic and wild animals. Bovine viral diarrhea virus is a prototypical representative of the pestiviruses of ruminant animals. Recently, new candidates appeared for including in this genus: two viruses of the wild ruminant animals that have not been officially classified and one HoBi-like virus discovered for the first time in the bovine fetal serum. The circulation of the ruminant animal pestiviruses within population of domestic and wild animals, the presence of these viruses in bioproducts stimulates studies of the infection reservoirs and their influence on the effect of the bovine viral diarrhea control programs.

Cross-priming amplification for detection of bovine viral diarrhoea virus species 1 and 2.

AIMS: The aim of the study was the development of cross-priming amplification for ubiquitous detection of bovine viral diarrhoea virus (BVDV) species 1 and 2. METHODS AND RESULTS: Three and five specific primers, respectively, for the detection of BVDV-1 and BVDV-2, were designed on the basis of the sequences of the 5'UTR region. Incubation temperature and reaction time were determined. The optimal incubation conditions using water bath were 63°C for 75 min. Reverse transcription step (RT) was not required. The results were visualized under UV-light as a bright yellow fluorescence in positive samples. Additional method for results interpretation was agarose gel electrophoresis. Positive samples showed the presence of ladder-like banding patterns, formed by harpin-like cross-priming amplification (CPA) products. Sensitivity of CPA was compared with conventional RT-PCR and real-time RT-PCR. The CPA detection limit was 3500 copies for BVDV-1 and 80000 copies for BVDV-2 per reaction. For RT-PCR it was 350 and 80 copies for BVDV-1 and BVDV-2, respectively, and for real-time RT-PCR it was 35 copies for BVDV-1 and 80 copies for BVDV-2. The sensitivity of the developed method is sufficient to detect persistently infected (PI) animals. Positive results were found in 24 of 25 BVDV isolates belonging to species 1 and 2. Additionally, one false-negative result for BVDV-2 was detected. There were no false-positive results in negative samples and in the negative control. Both sets of primers used for the detection of BVDV-1 and BVDV-2 were not able to detect atypical pestiviruses. CPA positive results were confirmed by RT-PCR and real-time RT-PCR. CONCLUSIONS: CPA is a rapid method for the detection of BVDV-1 and BVDV-2 in field samples from PI animals. SIGNIFICANCE AND IMPACT OF STUDY: This is the first report on the application of the CPA method for the detection of BVDV.

First report of bovine viral diarrhoea virus-2 infection in cattle in Poland.

This report describes the first identification in Poland of bovine viral diarrhoea virus (BVDV)-2 in a dairy herd where severe clinical disease with losses of young animals was observed. The virus was readily cultivated in cell culture and a phylogenetic analysis of the nucleotide sequences and secondary structures of the viral genomic 5' untranslated region confirmed virus identity. The economic impact of the infection was significant compared to the previously prevalent BVDV-1 infections confirming that this genotype of BVDV can cause severe sickness in affected herds. The use of BVDV-1 vaccine did not prevent the infection with the BVDV-2 genotype.

Immunogenicity of recombinant BCGs expressing predicted antigenic epitopes of bovine viral diarrhea virus E2 gene.

To develop a vaccine to prevent diseases caused by Mycobacterium tuberculosis and bovine viral diarrhea virus (BVDV) simultaneously, recombinant Bacillus Calmette-Guerin (rBCG) vaccines expressing different regions of the BVDV E2 gene were constructed. Using DNASTAR 6.0 software, potential antigenic epitopes were predicted, and six regions were chosen to generate recombinant plasmids with the pMV361 vector (pMV361-E2-1, pMV361-E2-2, pMV361-E2-3, pMV361-E2-4, pMV361-E2-5 and pMV361-E2-6, respectively). The recombinant plasmids were transformed into BCG, and protein expression was thermally induced at 45 °C. Mice were immunized with 5 × 10(6) CFU/200 µL of each rBCG strain. Compared with other groups, BVDV E2 specific antibody titers were higher in mice immunized with rBCG-E2-6. Ratios and numbers of CD4+, CD8+ and IL-12 expressing spleen lymphocytes of the rBCG-E2-6 group also were higher than those of other groups. Thus, the rBCG-E2-6 vaccine showed the highest immunogenicity of all groups based on the humoral and cellular responses to vaccination.

Insertion and stable expression of Gaussia luciferase gene by the genome of bovine viral diarrhea virus.

As a tool to address selected issues of virus biology, we constructed a recombinant cDNA clone of bovine viral diarrhea virus (BVDV) expressing Gaussia luciferase (Gluc) reporter gene. A full-length genomic cDNA clone of a non-cytopathic BVDV isolate was assembled by recombination in yeast Saccharomyces cerevisiae. The Gluc gene was inserted between the N(pro) and Core protein coding regions by recombination. The cDNA transcribed in vitro was infectious upon transfection of MDBK cells, resulting in reporter gene expression and productive virus replication. The rescued viruses were stable for 15 passages in cell culture, maintaining the replication kinetics, focus size and morphology similar to those of the parental virus. Expression and correct processing of the reporter protein were also maintained, as demonstrated by Gluc activity. These results demonstrate that genes up to 555 bp are simply assembled by a single step in yeast recombination and are stably expressed by this cDNA clone.

Genetic diversity of bovine viral diarrhea viruses in commercial bovine serum batches of Chinese origin.

Bovine viral diarrhea virus (BVDV) is often detected in commercial bovine serum. BVDV genetic diversity was investigated in commercial bovine serum of Chinese origin. Twenty-two batches of bovine serum were obtained from 10 suppliers with different geographic origins in China, and 20 batches of bovine serum were positive by reverse-transcription polymerase chain reaction (RT-PCR) and sequencing. Phylogenetic reconstructions of partial 5'UTR sequences indicated that the samples examined in this work clustered within the BVDV type 1 and BVDV type 2 genotypes. Interestingly, 3 sample sequences clustered into CSFV. These results suggest a high genetic diversity in Chinese BVDV field isolates. This study will benefit epidemiological surveys of BVDV detected in China.

Intoxicação aguda por Pteridium arachnoideum e Pteridium caudatum em bovinos e distribuição das plantas em Mato Grosso / Acute poisoning by Pteridium arachnoideum and Pteridium caudatum in cattle and distribution of the plants in Mato Grosso

São descritos os aspectos epidemiológicos, clínicos e patológicos de um surto de intoxicação por Pteridium arachnoideum e Pteridium caudatum em bovinos no Estado de Mato Grosso. A distribuição dessas plantas no Estado, a intensidade de invasão de pastagens e alguns fatores associados à invasão das pastagens por Pteridium spp. são também descritos. Pteridium spp. foi observada em 83 propriedades de nove municípios de Mato Grosso e deste total, amostras de 22 propriedades foram coletadas para identificação taxonômica. Em 22 propriedades identifica-se P. arachnoideum e em duas dessas havia também P. caudatum. O desmatamento e a realização de queimadas parecem estar relacionados com a invasão de Pteridium spp. nas pastagens. Na propriedade em que ocorreu a doença, 306 bovinos foram introduzidos em uma pastagem formada por Brachiaria brizantha intensamente invadida por P. arachnoideum e P. caudatum e desses 22 bovinos adoeceram e morreram. Os principais sinais clínicos foram febre alta, apatia, fadiga, fraqueza e decúbito. Na necropsia havia graus variáveis de hemorragias em vários órgãos e cavidades e infartos ocasionais. Microscopicamente, a alteração mais importante consistiu em aplasia severa da medula óssea vermelha. Os achados epidemiológicos, clínicos e patológicos associados à identoificação taxonômica da planta fundamentam o diagnóstico de intoxicação aguda por P. arachnoideum e P. caudatum em bovinos. O crescente desmatamento e a frequente utilização de queimadas em Mato Grosso podem contribuir para que esta doença venha a ser uma importante fonte de prejuízos para a pecuária do Estado.

Epidemiological features, clinical signs and pathological findings of a spontaneous acute poisoning by Pteridium arachnoideum and Pteridium caudatum in cattle in the State of Mato Grosso, Brazil, are described. The plant distribution, magnitude and some aspects about the pasture invasion by P. arachnoideum and P. caudatum in the State are also described. Pteridium spp. were found in 83 farms from nine counties and 22 of them were submitted to taxonomic identification. P. arachnoideum was found in 22 farms and in two farms also P. caudatum. Deforestation and burning appear to be associated with pasture invasion by Pteridium spp. On the farm where the poisoning occurred 306 cattle were introduced into a pasture of Brachiaria brizantha intensely invaded by P. arachnoideum and P. caudatum. Twenty two cattle were poisoned by the plants and died. The main clinical signs were hemorrhages, high fever, apathy, fatigue, weakness and recumbency. Gross findings included variable degrees of hemorrhages in several organs and cavities with occasional infarcts. The most consistent histological finding was marked bone marrow aplasia. Epidemiological, clinical and pathological findings associated with the taxonomic identofication of the plant support the diagnosis of acute poisoning by P. arachnoideum and P. caudatum in cattle. The increasing rate of deforestation and frequent burning in Mato Grosso can contribute to this disease which becomes a major cause of economic losses to livestock production in the State.

Effects of in utero pestivirus infection on bovine fetal bone geometry, biomechanical properties and composition.

Transplacental viral infection of the fetus can result in abnormal trabecular and cortical bone modeling in long bones through impaired bone resorption and formation. Although such infections are frequently associated with neonatal fractures in humans and animals, their effect on the biomechanical properties of the developing skeleton remain poorly understood. The goal of this study was to determine the effects of transplacental bovine viral diarrhea virus (BVDV) infection on the biomechanical properties of fetal femora. Pregnant heifers were inoculated intranasally with non-cytopathic BVDV or media alone on day 75 of gestation to produce persistently infected (PI) and control fetuses, respectively, which were then removed on days 192 and 245 of gestation. Histomorphometry, compositional analysis and 'four-point bending until failure' were performed on fetal femora. Altered cortical geometry largely accounted for differences in calculated elastic modulus (PI vs. control, and day 192 vs. day 245) and ultimate stress (day 192 vs. day 245). Fetal infection with BVDV did not significantly impair inherent biomechanical properties of bone but rather resulted in decreased periosteal apposition rates, manifested as smaller femoral mid-diaphyseal diameters. There were no differences between PI and control fetuses in cortical thickness ratio, ash density or calcium/phosphorous content; however, cortical thickness ratio decreased with fetal age. Thus even when cortical thickness ratios are similar, differences in mid-diaphyseal diameter affect the error associated with the calculation of stress and strain by classical beam theory equations.

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 2 months 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 evaluation of circulating bovine viral diarrhea virus type 2 maternal antibody level and response to vaccination in Angus calves.

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.