Bovine Viral Diarrhea Virus Antigen Research Articles

Determination of presence and prevalence of Bovine Viral Diarrhea Virus infection in cattle herds in Bingol province

Persistant bovine viral diarrhoea virus (BVDV) is an important cultivate disease in cattle breeding. Persistent infected (PI) animals are the main virus carrier within and between flocks at virus transmission. Consequently the presence of persistent ınfected (PI) animals should be determined and removed from the herd. In this study, a total of 105 blood samples collected from the cattle were brought to the Bingol University Faculty of Veterinary Medicine around Bingol for different purposes. The presence of BVDV antigen and antibodies in these blood samples was investigated by enzyme immunoassay (ELISA) test. The presence of BVDV antigens in12/105 ( 11.42% ) and antibodies in 40/105 (38.09%) were detected of the samples. On the other hand In the tree cattle BVDV antibody was not detected but only the antigen was detected. This states that 3/105 (2.85%) animals had persistent BVDV infection. These animals are constantly sick and they spread out the virus. In this article, the presence and the incidence of persistent BVDV in the region was demonstrated 3/105 (2.85%) by this study. It has emphasized the need to control of the disease in the region for rational cattle breeding in the province. Eradication offers the supplementary advantage of developed herd health; however, it also composes a favorable cattle population that needs to be screened by strict biosecurity.

Influence of bovine viral diarrhea virus infections on AI conception and breeding season pregnancy success in vaccinated beef herds

Bovine viral diarrhea virus (BVDV) causes reproductive and economic losses in cattle. The objective of this study was to evaluate the influence of BVDV infections on reproductive success in previously vaccinated herds. Vaccinated cows (n=370) and heifers (n=528) from 9 herds were synchronized and artificially inseminated (AI). On d 28 following insemination, blood samples were collected and pregnancy status was determined. Non-pregnant animals were resynchronized and inseminated a second time. Blood samples were tested for the presence of BVDV antigen. Animals that tested positive were considered infected with BVDV. Herds with at least 1 positive animal were determined to be BVDVinfected (n=4 infected, n=5 non-infected). Statistical analyses were performed using the GLIMMIX procedure of SAS with herd as a random variable. Herds with BVDV infections at d 28 had significantly decreased (P < 0.01) AI conception rates compared to non-infected herds (34 ± 2.3% vs 56 ± 2.3%). Breeding season pregnancy rates were also decreased (P < 0.01) in BVDV-infected herds compared to non-infected herds (68 ± 3.1% vs 88 ± 6.9%). In conclusion, BVDV infections in previously vaccinated herds had a negative impact on AI conception rates and breeding season pregnancy success.

Detection of Respiratory Viral Antigens in Nasal Swabs of Bovine by Sandwich ELISA

Bovine Respiratory diseases are responsible for economic losses in livestock industry worldwide. The present study aiming to investigate the occurrence of respiratory viral antigens of Bovine herpesvirus-1 (BoHV-1), Bovine respiratory syncytial virus (BRSV), Bovine viral diarrhoea virus (BVDV) and Bovine parainfluenza 3 virus (BPI3V) in bovines and describe the distribution of respiratory viruses in unvaccinated animals in Punjab. A total of 55 nasal swab samples were collected from the cattle and buffaloes exhibiting the clinical signs of respiratory disease. All samples were tested for the detection of all four viral antigens by commercially available sandwich ELISA kit. BoHV-1 and BPI3V antigen were detected in 1 and 3 samples with the percentage of 1.8 and 5.4, respectively, whereas none of the sample was found positive for BRSV and BVDV antigen. The present study concluded the existence of BoHV-1 and BPI3V infection in respiratory tract and plays the important role in the respiratory viral infections of bovines. This study suggests the prevention measures should be taken to control the economic losses due to respiratory diseases in cattle and buffaloes.

Evaluation of currently available bovine viral diarrhoea virus (BVDV) and HoBi-like pestivirus (HoBiPeV) specific diagnostic tests in detection of highly divergent HoBiPeVs in cattle

The emergence of novel and divergent HoBi-like pestivirus (HoBiPeV) strains in cattle in Asia recently has raised concerns with regard to their reliable and accurate diagnosis. Hence, the aim of this study was to evaluate currently available BVDV diagnostic tests and HoBiPeV-specific diagnostic tests in detection of genetically divergent strains of HoBiPeV. One strain each of HoBiPeV-c and d were subjected to two BVDV diagnostic RT-PCR tests, one HoBiPeV specific RT-PCR test, three BVDV diagnostic qRT-PCR tests, one HoBiPeV specific qRT-PCR test and two BVDV antigen capture ELISAs. Archived cattle sera (n = 41) from farms with reports of HoBiPeV natural infection were assessed for detection of HoBiPeV antibodies by VNT and two commercial BVD antibody ELISA kits. BVDV diagnostic qRT-PCR tests had better sensitivity than BVDV diagnostic RT-PCR tests, while majority of them except a commercial kit showed a lower sensitivity for HoBiPeV-d strain. The HoBiPeV specific qRT-PCR test was found more sensitive than HoBiPeV specific RT-PCR but both had lower sensitivity for HoBiPeV-d strain, as displayed by primer/probe sequence mismatches. The BVDV Erns antigen ELISA detected both the strains of HoBiPeV, but with a lower sensitivity for HoBiPeV-d strain, whereas BVDV NS3 antigen ELISA failed to detect them even at a high HoBiPeV titre. Compared to VNT, commercial BVDV antibody ELISA showed low to moderate sensitivity in detection of HoBiPeV antibodies, with a failure rate of 31.25% for the whole virus antigen based ELISA and a failure rate of 56.25% for NS3 antibody ELISA. The present study demonstrated new challenges in HoBiPeV diagnosis indicating a need in improvement of both HoBiPeV specific diagnostic RT-PCR and qRT-PCR for better utility in HoBiPeV epidemiology and biological product safety. Although more studies are required, this study reinforces that combined use of BVDV Erns and NS3 antigen ELISA may have some utility in preliminary differentiation between HoBiPeV and BVDV infection in PI cattle. Additionally, we show that the comparative VNT has a better sensitivity in detection of HoBiPeV exposure and there is a need of robust antibody ELISA for reliable detection of antibodies against this emerging bovine pestivirus.

Genetic analysis of NS5B gene from bovine viral diarrhea virus-infected cattle in Central and East Java, Indonesia.

Background and Aim:A previous study divided Indonesian bovine viral diarrhea virus (BVDV)-1 into subgenotypes BVDV-1a to BVDV-1d based on the partial NS5B gene using strain Bega as reference for BVDV-1a. In fact, it is clustered into BVDV-1c with strain Bega-like Australia. BVDV genotyping has been done on isolates from Jakarta, West and Central Java, but East Java isolates have not been genotyped. This study aimed to analyze genetic variability and amino acid residues in the nucleotide-binding pocket of the NS5B gene from infected cattle.Materials and Methods:Samples were obtained from the Sera Bank originating from active and passive surveillance of cattle that had been tested for BVDV antigen from 2013 to 2017. Detection of the p80 antibody and BVDV genotyping was carried out using ELISA and nested-multiplex-polymerase chain reaction (PCR), respectively. We defined 15 nested PCR products for partial sequencing of NS5B. Those field samples were selected from each location and year using proportional calculation as a representative sample. Homological and phylogenetic analyses of the partial NS5B gene were performed using BLAST and MEGA version 6.Results:Based on the phylogenetic tree analysis using 360 nucleotides as the partial NS5B gene, Indonesian BVDV-1 isolates from Central and East Java were subdivided to BVDV-1a (n=9), BVDV-1b (n=1), and BVDV-1c (n=5). In the present study, the homology of BVDV subgenotype -1a, -1b, and -1c was compared to the BVDV GenBank data and found 90-93%, 93%, and 92-95% respectively with the average pairwise distance of 0.207. A point mutation was shown at R283K of all BVDV isolates based on the sequence of three amino acid residues R283, R285, and I287 in the nucleotide-binding pocket as a part of the encoded RNA-dependent RNA polymerase.Conclusion:This study revealed the genetic variability of BVDV infecting cattle in Central Java and East Java, Indonesia, the subtypes BVDV-1a, BVDV-1b, BVDV-1c, and a point mutation at the R283K residue.

Slaughterhouse survey for detection of bovine viral diarrhea infection among beef cattle in Kyushu, Japan.

Bovine viral diarrhea virus (BVDV) footprint has spread across the globe and is responsible for one of the most economically important diseases in cattle. In Japan, some regional surveillance and preventive measures to control bovine viral diarrhea (BVD) have been implemented. However, BVDV infection is poorly understood in cattle industries, and there is no systematic BVD surveillance system and control program. Kyushu is the center for raising beef cattle in Japan. Therefore, this study aimed to determine the BVDV infection using a slaughterhouse survey among beef cattle in Kyushu, Japan. A total of 1,075 blood samples were collected at two regional slaughterhouses in Miyazaki prefecture from December 2015 to June 2016. Antigen ELISA was used for detection of BVDV antigen in blood samples. Two samples showed positive results (2/1,075; 0.18%). BVDV RNA was extracted from positive blood samples; the sequence was determined and analyzed by the neighbor-joining method for construction of the phylogenetic tree. Phylogenetic analysis based on the 5’-UTR revealed that the two positive samples were grouped into the same subtype BVDV-1b in the BVDV-1 genotype, but the infected cattle belonged to two different farms. In conclusion, this is the first study to identify the presence of BVDV in a slaughterhouse survey in Kyushu. These findings suggest that a slaughterhouse survey is a useful tool for developing a surveillance system for monitoring infectious diseases in cattle.

Investigation of persistent infection of bovine viral diarrhea virus (BVDV) in Holstein dairy cows.

The aim of this study was to investigate the persistent infection (PI) of bovine viral diarrhea virus (BVDV) along with its coexistence between BVDV antibody titer and BVD virus in blood of Holstein dairy cows. Only large commercial farms (each contained < 1000-3000 unvaccinated cows) were included. There were 11 dairy cattle herds. They included nearly 20,000 dairy cows. Totally, 140 cows, > 3months to almost 10years old, were randomly sampled. Indirect enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR) were used to detect BVDV antibody and virus, respectively. The percent positivity (PP) < 14 and ≥ 14 values are interpreted negative and positive, respectively. Simultaneously, whole blood samples pooled in groups of 10 animals were used for molecular detection of BVDV. The results revealed that 138 (98.56%) out of 140 cows were positive for BVDV antibody, while the BVDV antigen was detected only in 2 (1.42%) cows, which were negative for BVDV antibody and so were considered as persistent infection (PI) cows. They were also retested 3weeks apart. Since the results showed the strong coexistence between seropositivity and BVD virus, in the infected dairy cattle herds, the combination of simple ELISA and pooled whole blood RT-PCR strategy could be an achievable approach to detect PI animals.

Pathological and virological features of skin lesions caused by BVDV in cattle.

Dermatitis might occur in mucosal disease (MD) caused by bovine viral diarrhea virus (BVDV). This study describes the pathological and virological features of skin lesions associated with BVDV infection in four persistently infected (PI) cattle. Skin samples were reprocessed for histopathology and IHC. BVDV isolates were obtained and were genetically characterized. In addition to upper alimentary system ulcerative lesions, all cattle (one outbreak and three individual cases) presented focal crusty and ulcerative lesions affecting the mucocutaneous and skin-horn junctions, interdigital clefts, pastern, and areas surrounding the dewclaws and diffuse thickened skin within 7-20days of infection. Microscopic analysis revealed parakeratotic hyperkeratosis and single-cell keratinocyte death, accompanied by ballooning degeneration and spongiosis in the epidermis, as well as intraepithelial and subcorneal pustules. IHC showed BVDV antigen in the cytoplasm of keratinocytes undergoing individual cell death. Phylogenetic analysis revealed that the isolates from cattle #1, #2, and #4 belonged to BVDV-1a, whereas that from cattle #3 belonged to BVDV-1d. Cytopathic BVDV was isolated from cattle #2 and #3 (MD), and non-cytopathic BVDV was isolated from cattle #1 and #4. Thus, BVDV infection might cause acute disease, characterized by skin and upper alimentary system ulcerative lesions, in both MD and PI cattle.

Prevalence of bovine viral diarrhea virus in dairy cattle herds in eastern China

Bovine viral diarrhea virus (BVDV) is a worldwide spreading pestivirus affecting cattle and other ruminants; however, there have been few reports on epidemiologic investigation of BVDV in eastern China. In this study, bulk tank milk from 36 herds of dairy cattle in eastern China was submitted to serological investigations, 77.8% of herds was BVDV antibody positive. Individual animal status in two herds was further investigated collecting blood samples, the positive ratio was 49.74% and 24.64%, and the average positive ratio of calves, heifers, and lactating cows was 15.94%, 40.16%, and 41.7%, respectively. Moreover, clinical survey was carried out among 8170 dairy cattle from 36 herds, for diarrhea syndrome, respiratory problems and reproductive failure, and pathogens of all clinical cattle were further investigated. The results showed that BVDV was one of the main pathogen, which infected animals combining with various other viruses. Then, nine BVDV strains were isolated; phylogenetic analysis showed that BVDV subtypes currently circulating in eastern China were BVDV 1a and BVDV 1c. In addition, out of 377 cows tested, the 1.86% detected positive to the BVDV antigen. This study provided the foundation of further study on vaccination and control strategies of BVDV in eastern China.

Epidemiological surveillance of bovine viral diarrhea and rift valley fever infections in camel.

Aim:This study was designed to investigate the current epidemiological situation of bovine viral diarrhea virus (BVDV) and rift valley fever virus (RVFV) infection of camels originating from Sudan “smuggler” and Egypt as part of our future plan for a national surveillance program in Egyptian provinces, which will aid in establishment of control strategy for animal diseases.Materials and Methods:This investigation was accomplished using serological diagnostic and molecular biology techniques. A total number of 200 blood samples were collected from camel (120 originated from Sudan “smuggler” and 80 from local breed) and were subjected for testing both BVDV and RVFV occurrence with different age and sex.Results:Sixty-six of the 200 camels (33%) were positive for BVDV antibodies, and 44 (22%) for BVDV antigen (Ag), and 27 of the 200 camels (13.5%) were positive for RVFV immunoglobulin G (IgG) antibodies. On the other hand, the seroprevalence of BVDV for antibodies (47.5%), Ag (31.6%), and RVFV IgG antibodies (16.6%) was higher in camel originated from Sudan “smuggler” than of local breed which was 11.2% for BVDV antibodies and 7.5% for BVDV Ag, while it was 8.7% for RVFV IgG antibodies. The incidence of BVDV antibodies, Ag, and RVFV IgG antibodies was the highest in male, up to 9 years of age. The frequency of positive cases was significantly different according to the origin of samples and sex and age of camel for BVDV and RVFV. In addition, seven serologically positive samples for BVDV and five serologically positive samples for RVFV were submitted as a buffy coat for molecular detection by one-step – reverse transcription polymerase chain reaction (RT-PCR). The results demonstrated that three samples were positive for BVDV of camel originated from Sudan (smuggler), while no RVFV Ag was detected in all five samples. Sequencing and phylogenetic analysis of the amplicons obtained from positive RT-PCR samples (three samples) indicated 100% nucleotide homology with Sudan strain 2015 except only one (missense point mutation) by substitution of A to T at position 345 that changed the coded amino acids from T (Threonine) to S (Serine) at residue 115.Conclusion:Camels act as risk animals for the introduction of many infectious diseases from Sudan to Egypt, especially transboundary animal diseases, so strict quarantine measures should be taken during importation of live animals from Sudan to prevent the spread of such diseases.

Recombinant E2 protein enhances protective efficacy of inactivated bovine viral diarrhea virus 2 vaccine in a goat model

BackgroundInactivated and subunit bovine viral diarrhea virus (BVDV) vaccines have shown limited protective efficacy. This study aimed to evaluate the effectiveness of a vaccine containing both inactivated BVDV (iBVDV) and baculovirus-expressed recombinant E2 (rE2), an important BVDV antigen with strongly neutralizing epitopes.ResultsFour groups of goats were immunized twice with one of four vaccine preparations: 1) iBVDV+rE2, 2) rE2, 3) iBVDV, and 4) saline, and challenged with BVDV. For goats vaccinated with the iBVDV+rE2 vaccine, no viremia was observed after challenge, and clinical signs, pyrexia, and leukopenia were reduced compared to the saline group. In contrast, for goats vaccinated with either iBVDV or rE2 alone, viremia was still detectable.ConclusionThe combination of iBVDV and rE2 elicited stronger protective immune responses against BVDV than iBVDV or rE2 alone.

Seroprevalence and factors associated with bovine viral diarrhea virus (BVDV) infection in dairy cattle in three milksheds in Ethiopia.

This work was conducted to estimate the seroprevalence, to identify potential factors that influence seroprevalence of bovine viral diarrhea virus (BVDV), and to investigate the association between BVDV serostatus and occurrence of reproductive disorders in dairy cattle in three milksheds in Ethiopia. A total of 1379 serum samples were obtained from cattle randomly selected from 149 herds from three milksheds representing central, southern, and western Ethiopia. Sera samples were examined for bovine viral diarrhea virus (BVDV) antibodies using commercial competitive enzyme-linked immunosorbent assay (ELISA) kit. Logistic regression analysis was employed to investigate associations between risk factors and the risk of BVDV seroprevalence, and BVDV serostatus and reproductive disorders. Seroreaction to BVDV antigens was detected in 32.6% of the 1379 cattle and 69.8% of the 149 herds sampled. Factors associated with BVDV seroplevalence were age, breed, and herd size (P < 0.05). Adult cattle ≥ 18months old had 2.1 (95% CI 1.5, 3.1) times the odds of BVDV seroreaction than younger cattle. Holstein-Friesian (HF) local crosses (OR = 2.1, 95% CI 1.3, 3.4) and HFs (OR = 1.3, 95% CI 0.9, 1.9) were more likely to be seropositive than Jersey and the odds of seropositivity in cattle in large herds with 11 or more animals were higher (OR = 1.8, 95% CI 1.3, 2.5) than the odds of BVDV seropositivity in smaller herds. Seroprevalence was not associated with geographical region (P > 0.05). Risk of reproductive disorders was not affected by BVDV serostatus, except for repeat breeding (P > 0.05). The present study demonstrated that BVDV has wide distribution in the country being detected in all the 15 conurbations and 69.8% of herds involved in the study.

Bovine herpesvirus-1 (BHV-1), bovine leukemia virus (BLV) and bovine viral diarrhea virus (BVDV) infections in Algerian dromedary camels (Camelus dromaderius).

This study was performed to investigate the presence of bovine herpesvirus-1 (BHV-1), bovine leukemia virus (BLV) and bovine viral diarrhea virus (BVDV) infections in dromedary camels (Camelus dromaderius) kept in mixed herds with sheep and goats in Algeria, since the prevalence of BHV-1, BVDV, and BLV infections among dromedary camels in Algeria is unknown. Totally, 111 camel sera were collected from two provinces (Laghouat and Ghardaia) in Algeria. The sera were analyzed for BHV-1 specific antibodies, BVDV specific antibodies and BVDV antigen using the ELISA, and BLV nucleic acid using PCR. The seropositivity rate was 9.0% for BVDV-specific antibody, although 41.4% of camels tested were positive for BVDV antigen. Moreover, there was no evidence of BHV-1 and BLV infections. The results indicated that camels might represent an important source for BVDV infection in all ruminants, including cattle, sheep, and goats bred in mixed herds in Algeria, since they had a higher BVDV prevalence rates. Therefore, the prevention and control measures for BVDV infection should put in place in camel populations to limit the spread of BVDV infection to ruminant populations in Algeria.

Prevalence of Candidatus Mycoplasma haemolamae, bovine viral diarrhoea virus, and gastrointestinal parasitism in a sample of adult New Zealand alpaca (Vicugna pacos)

AIM: To determine the prevalence of infection with Candidatus Mycoplasma haemolamae (Mhl), antibodies to bovine viral diarrhoea virus (BVDV), and BVDV antigen, and the prevalence of animals with elevated faecal nematode egg counts (FEC) in a sample of adult New Zealand alpaca (Vicugna pacos).METHODS: Blood samples were obtained from 175 alpaca, collected from 15 farms around New Zealand, and from 31 samples sent to a diagnostic laboratory for routine haematology. Blood smears (n=170) were examined microscopically for the presence of haemoplasma, and DNA was extracted from whole blood (n=206) for real-time PCR testing for Mhl. Packed cell volume (PCV) was determined for 193 samples. Serum samples (n=195) were tested for BVDV antibody using ELISA, and for BVDV antigen using a real-time PCR assay. Faecal samples were collected from 143 animals; FEC were measured, and samples pooled for larval culture.RESULTS: No haemoplasma organisms were present on blood smear examination. Of the 206 blood samples, two (from the same farm) were positive for Mhl by real-time PCR testing, giving a prevalence of infection with Mhl of 0.97%. Of the 195 serum samples tested, four (2.1%) were positive for antibodies to BVDV; animals with BVDV antibodies were from 3/15 (20%) farms, none of which farmed cattle. None of the serum samples were positive by PCR for BVDV antigen. The median FEC was 50 epg (min 0, max 4,700), with 55/143 (38.5%) samples having 0 epg, and 33/143 (23.1%) having ≥250 epg. Haemonchus spp. were the most common nematodes present in faecal larval cultures from the North Island. Log10 FEC was negatively associated with PCV (p=0.02), and was higher in males than females (p<0.001), and in animals that were positive compared with negative for Mhl (p=0.022).CONCLUSIONS AND CLINICAL RELEVANCE: The number of alpaca infected with Mhl was low, as was the seroprevalence of BVDV. Gastrointestinal parasitism was, however, a common finding in this sample of New Zealand alpaca.

Herd-level prevalence of selected endemic infectious diseases of dairy cows in Great Britain

To implement appropriate and effective disease control programs at the national level, up-to-date and unbiased information on disease frequency is needed. The aim of this study was to estimate the prevalence of selected endemic infectious diseases in the population of dairy herds in Great Britain. Bulk milk tank (BMT) samples from 225 randomly selected dairy farms, stratified by region and herd size, were tested for antibodies against bovine viral diarrhea virus (BVDV), bovine herpesvirus type 1, Mycobacterium avium ssp. paratuberculosis, Leptospira Hardjo, Salmonella spp., Coxiella burnetii, Fasciola hepatica, Neospora caninum, and Ostertagia ostertagi. Furthermore, the presence of BVDV, C. burnetii, and Chlamydia-like organisms was determined by PCR. The apparent herd prevalence was estimated as a weighted proportion of positive herds. The true prevalence was calculated when a test was used with known test characteristics for the cut-off value used. Among unvaccinated herds, the true prevalence of BMT antibodies against BVDV was estimated at 66% [95% confidence interval (CI): 56-77%], M. avium ssp. paratuberculosis 68% (95% CI: 59-77%), bovine herpesvirus type 1 62% (95% CI: 52-73%), Leptospira Hardjo 47% (95% CI: 34-60%), and Salmonella spp. 48% (95% CI: 39-56%). The apparent prevalence of BMT antibodies against C. burnetii was 80% (95% CI: 75-85%), F. hepatica 55% (95% CI: 48-62%), N. caninum 46% (95% CI: 38-54%), and O. ostertagi 95% (95% CI: 91-98%). The BVDV, C. burnetii, and Chlamydia-like antigens were detected in 5 (95% CI: 2-9%), 29 (95% CI: 21-36%), and 31% (95% CI: 24-38%) of herds, respectively. Our results show that dairy cows across GB are frequently exposed to the studied pathogens, which are endemic at high levels with some geographical variations. These prevalence estimates provide a much-needed basis to assess whether nationwide control programs for the studied pathogens are justified by their potential economic, environmental, and public health implications. Should surveillance and control programs be initiated, the estimates presented here are a baseline against which progress can be assessed.

Case report

Bovine viral diarrhea virus (BVDV) continues to be a challenge for the cattle industry despite routine vaccination that includes killed or modified-live BVDV antigens. At a commercial dairy, 1,081 newborn calves were tested for BVDV antigen by pooled reverse transcription polymerase chain reaction as part of a screening program. Immunohistochemistry confirmed persistent BVDV infections in 13 calves. Ten of the PI calves were available for BVD typing. Both cytopathic and non-cytopathic BVD viruses were isolated. The non-CPE viruses typed as BVD type lb with a total of 3 different strains found; an identical strain found in 2 calves, another identical strain found in 2 other calves, and a third identical strain found in 3 other calves. A BVDV control program relying solely on BVD vaccination using a modified-live vaccine did not protect calves in this herd from persistent infection with type lb BVDV. These results demonstrate that control programs that rely only on vaccination to control BVDV without testing for the presence of PI animals are not adequate to control BVD.

The risk of transmission from sheep experimentally infected with BVDV-1c during the acute phase to BVDV naïve sheep

Bovine viral diarrhoea virus (BVDV) is an economically important disease of cattle known to cause immunosuppression and reproductive dysfunction in infected animals. Although predominantly a disease of cattle other ruminant species, such as sheep, have been shown to undergo infection with similar outcomes as those observed in cattle.The main source of BVDV transmission is known to be persistently infected (PI) animals which shed large quantities of virus through all secretions and excretions. However, it is believed that BVDV is able to persist within herds even after the removal of these PI animals. Although not proven, this persistence is thought to be due to the short period of viral excretion shown to occur in acutely infected animals. As a result the aim of this study was to determine if transmission of BVDV could occur between sheep undergoing an acute BVDV infection and sheep naïve to BVDV.Five wethers, experimentally infected with BVDV-1c, were co-mingled with five pestivirus naïve wethers for a period of seven weeks. Weekly blood samples were collected and tested for the presence of BVDV-specific antibodies and BVDV antigen. Acute infection was successful in the experimentally inoculated animals, with antibodies detected in all five wethers by Day 35 post inoculation. Transmission of BVDV-1c was not shown to occur between these acutely BVDV-1c infected wethers and the naïve wethers co-mingled with them.

Viral shedders in a herd vaccinated against infection with bovine viral diarrhoea virus (BVDV) without prior testing for the presence of persistently infected animals

Abstract Introduction: Bovine viral diarrhoea (BVD), caused by the bovine viral diarrhoea virus (BVDV), is one of the most important diseases of cattle worldwide. The purpose of the study was to determine the BVDV infection status in a dairy herd vaccinated against BVD. Before vaccination started in 2008, there had been no prior identification or the removal of the possible source of infection (persistently infected animals). It was expected that vaccination itself would enable the elimination of viral shedders on a long term basis. Material and Methods: Serological screening for antibodies against BVDV with determination for antibodies titres, BVDV antigen, and the presence of the viral genome with phylogenetic analysis of positive samples in the herd were performed, despite the lack of any clinical problems indicating possible presence of BVDV infection. Results: 19 individuals persistently infected with BVDV were identified among calves and heifers but not in adult cattle. All virus shedders were antibody negative and the genotype of isolated virus was BVDV-1b, indicating a single source of infection. The vaccine used in the herd was composed of BVDV-1a strain. In each of the tested cowsheds, antibody titres against BVDV-1b were higher than against BVDV-1a (median values). Conclusion: Despite a long-lasting vaccination programme and relatively high sequence homology of vaccinal and field strains of BVDV (83.6%), it was not possible to avoid transplacental infections of foetuses and the birth of persistently infected calves from vaccinated heifers although the protection against clinical disease was accomplished.

Effect of injectable trace mineral administration on health, performance, and vaccine response of newly received feedlot cattle

ABSTRACT Previous research has established that trace minerals are necessary for optimal growth and immunity, yet challenges exist with intake of dietary trace minerals in cattle newly received at feedlots. A total of 128 crossbred beef bull (n = 40) and steer (n = 88) calves were used for this 42-d receiving study. Cattle were stratified by initial BW (275 ± 9.54 kg) and sex (steer or bull) and then assigned equivalently to treatment pens (n = 8 per treatment). Treatments were (1) negative control (CON) or (2) injectable trace mineral solution containing 60 mg of Zn/mL (as Zn disodium EDTA), 10 mg of Mn/mL (as Mn disodium EDTA), 5 mg of Se/mL (as sodium selenite), and 15 mg of Cu/mL (as Cu disodium EDTA) administered s.c. at 2.2 mL/100 kg of BW on d 0 (ITM). Health was monitored daily by trained personnel blinded to treatment pen assignment. Blood samples and BW were obtained on d 0, 14, 28, and 42 to determine bovine viral diarrhea virus (BVDV) type 1a antibody titer and gain performance. Standard processing procedures were applied on d 0, including administration of a respiratory vaccine containing modified-live BVDV antigens. No difference in overall ADG (P = 0.21) was detected between CON (1.36) and ITM (1.25 kg/d) steers. Overall DMI was not different (P = 0.83) between CON (6.98) and ITM (7.02 kg/d), but G:F tended (P = 0.08) to be less for ITM from d 28 to 42. The morbidity rate observed in this study was low (14% average), and there was no difference (P = 0.71) in morbidity between treatments, which averaged 15.6 and 12.5% for CON and ITM, respectively. There was a treatment × d interaction (P = 0.09) for BVDV-specific antibody titer. On d 14, ITM had a greater (P = 0.02) BVDV antibody titer than CON. These data suggest that ITM did not improve performance or morbidity when the incidence was low; however, the BVDV-specific antibody response to a respiratory vaccine was greater for ITM on d 14.

Natural Outbreak of BVDV-1d-Induced Mucosal Disease Lacking Intestinal Lesions.

Bovine viral diarrhea virus (BVDV) belongs to the Pestivirus genus, which is further divided into subgenotypes (1a-1u and 2a-c). When persistent infection occurs, the calf will be immunotolerant to BVDV and possibly develop mucosal disease. This study describes an outbreak of BVDV-1d-induced mucosal disease lacking intestinal lesions. Eleven calves presented with anorexia, sialorrhea, lameness, recumbency, and death. Three calves were necropsied, showing ulceration of the interdigital skin and the oral and nasal mucosa; linear ulcers in the tongue, esophagus, and rumen; and rounded ulcers in the abomasum. Microscopically, mucosa and skin had superficial necrosis, with single-cell necrosis and vacuolation in epithelial cells, and severe parakeratosis. Immunohistochemistry (IHC) showed BVDV antigen in the cytoplasm of epithelial cells in skin and mucosa. All 11 dead calves were positive upon reverse transcription-polymerase chain reaction (RT-PCR) for the detection of Pestivirus along with another 11 live calves from the herd, which were positive again by RT-PCR and IHC after a 4-week interval. Sequencing of the 5' untranslated region and N-terminal protease showed that viruses from these 22 calves were homologous and of subgenotype BVDV-1d. Cytopathic BVDV was isolated from 8 of 11 dead calves, but only noncytopathic BVDV was isolated from the 11 live animals. The findings indicate that this was an outbreak of mucosal disease caused by BVDV-1d, with high morbidity, and lesions restricted to the upper alimentary system and skin and absent from intestine. Thus, the epidemiological and pathological features in this form of mucosal disease may be similar to vesicular diseases, including foot and mouth disease.