Dataset: 11.1K articles from the COVID-19 Open Research Dataset (PMC Open Access subset)
All articles are made available under a Creative Commons or similar license. Specific licensing information for individual articles can be found in the PMC source and CORD-19 metadata.
More datasets: Wikipedia | CORD-19
Deep Learning Technology: Sebastian Arnold, Betty van Aken, Paul Grundmann, Felix A. Gers and Alexander Löser. Learning Contextualized Document Representations for Healthcare Answer Retrieval. The Web Conference 2020 (WWW'20)
Funded by The Federal Ministry for Economic Affairs and Energy; Grant: 01MD19013D, Smart-MD Project, Digital Technologies
Antibiotic treatment of bacterial pneumonia must be sufficient in duration and, most crucially, early enough to prevent lesions forming that may resist both therapy and regeneration of normal lung parenchyma. The emphasis should be on early treatment and first treatment success in cases of calf pneumonia since the outcome for those animals that fail to respond successfully to first treatment is poor. Typically, one third to two thirds of animals that do not respond to initial therapy are permanently affected or lost.
The effectiveness of metaphylaxis (defined as mass medication of all animals on arrival in the feedlot) in reducing morbidity rates associated with pneumonia in feedlots is variable. A recent meta-analysis of North American studies estimated a decrease in mortality and morbidity of 2% and 26%, respectively for animals that received antimicrobial treatment on arrival in the feedlot. The average daily weight gain was 0.11 kg higher in these animals in comparison with calves not receiving metaphylactic treatment.
The use of antimicrobials for prevention (prophylaxis or metaphylaxis) of calf pneumonia has to be seen in the context of increasing pressure on the veterinary profession to promote prudent use of antibiotics, noting that indiscriminate use of antibiotics promotes the selection and subsequent proliferation of antibiotic-resistant strains of bacteria. The European Parliament recently called for a review of current practices of prophylactic use of antimicrobials.
Non-steroidal anti-inflammatory drugs (NSAIDs) have shown to reduce pyrexia, clinical signs, and lung pathology, and improve average daily weight gains in calves with respiratory disease compared to untreated calves or calves only treated with antimicrobials. Other studies, however, have not found significant differences between treatment groups. The cost-efficiency of additional anti-inflammatory therapy in bovine respiratory disease is uncertain.
It has been suggested that pneumonic animals should be isolated in appropriate facilities. However, there is little experimental evidence to quantify the benefits and it may lead to practical difficulties.
Moderately to severely depressed calves with a high respiratory rate (≥ 65/min) and temperature ≥ 40.0 °C were treated with 0.5 mg/kg meloxicam for pain relief and anti-inflammatory effect. When bacterial pneumonia was suspected, 20 mg/kg procain benzylpenicillin was administered IM once daily for five days. Euthanasia was performed by stunning with a captive bolt, followed by bleed-out.
The efficacy and economical viability of vaccination against respiratory disease in calves remains uncertain. Although substantial relevant literature is available, a consensus, underpinned by robust scientific findings, has not yet been achieved. The evaluation of vaccine efficacy, and the interpretation of trial results, is complicated by the nature of bovine respiratory disease, and in particular the multitude of pathogens and environmental stressors that contribute to disease development. Additionally, the disease pattern of pneumonia in calves can vary under a variety of husbandry systems, as a consequence of differing challenges at different points in the rearing period.
Modified live vaccines, inactivated vaccines, or subunit vaccines are available for most of the major pathogens. For the most part, relevant research has focused on the ability of these vaccines to trigger an immune response or to decrease clinical disease and pathogen shedding in challenge trials. Although field trials are needed to provide conclusive evidence of vaccine efficacy under field conditions, few of these have been reported. In a very recent paper, where a field trial was conducted, Windeyer could find no beneficial effect of vaccination with a multivalent respiratory vaccine in a large population of young dairy calves with a low incidence of failure of passive transfer.
Substantial data are available on pneumonia in feedlot cattle, predominantly from the USA. These data provide useful insights, albeit for different husbandry systems, of the impact of multiple stressors on recently weaned suckler calves. The feedlot studies clearly indicate that vaccination provides best results when carried out in healthy animals and prior to the exposure to defined stressful events, such as weaning, marketing, transportation and associated changes in environment. Vaccination together with further management measures (preconditioning) in suckler calves before weaning has been shown to be beneficial on the performance of these animals after arrival in feedlots. However, in these studies the benefit of vaccination and management procedures cannot be assessed independently. Perino and Hunsaker conducted a review of field trials to assess the efficacy of mono- or multivalent vaccination against bovine respiratory disease without preconditioning. Using outcomes of morbidity and mortality in feedlot cattle, these authors identified 9 studies with positive and 13 studies with neutral or negative outcomes.
Early studies with formalin-inactivated experimental Bovine Respiratory Syncytial Virus vaccines demonstrated enhancement in disease severity after subsequent infection. Meanwhile the safety and efficacy of modified live and inactivated BRSV vaccines have been demonstrated in experimental challenge trials, whereby reduced clinical disease and lung lesions have been found in most but not all trials. Monovalent BRSV vaccines have rarely been tested in field trials. Van Donkersgoed et al tested a modified live BRSV vaccine in eight different scenarios in calves and yearlings and found only significant reduction of cases of bovine respiratory disease in 2 groups. However, all animals were comingled throughout the trials, which suggests that the development of herd immunity could have affected the apparent efficacy of the vaccine.
Young calves do not produce specific antibodies after vaccination in the presence of maternally derived immunity. For this reason, it is commonly believed that maternal antibodies can interfere with the efficacy of vaccination. To overcome this issue, research in recent years has focused on the use of the mucosal immune system for vaccination. Intranasal vaccination against BRSV proved effective in challenge studies in calves without maternal antibodies. In calves with maternal antibodies against BRSV, protective effect of intranasal vaccination compared to an unvaccinated control group was confirmed in two studies. However, Ellis et al. could not prevent clinical disease and lung lesions in calves with or without maternal antibodies that were challenged 4.5 months after intranasal vaccination with a modified-live virus vaccine.
Depending on virus virulence and host resistance, Bovine Herpes Virus 1 infection can cause clinical pictures from severe classical Infectious Bovine Rhinotracheitis (IBR) to no clinical signs at all. Regardless, infection will lead to latency in the host. In relation to calf pneumonia, it is important to consider the immunosuppressive effect of BoHV1 infection as well as BoHV1 reactivation. Conventional BoHV-1 vaccines containing modified live virus are very effective, inducing both humoral and cellular immune responses. However, they can establish latency and can be reactivated with adverse effects on pregnant cows or young calves in contact with the vaccinated animals. Inactivated vaccines, on the other hand, are safe but less efficacious as they only stimulate humoral immunity. Gene-deleted (gE-) modified live virus and inactivated marker vaccines, to distinguish vaccination from field virus infection, have been developed and are commercially available. Vaccination of newborn calves, especially in the presence of maternal antibodies, poses the same challenges as described for BRSV vaccination and is in the focus of current research. Intranasal vaccination of seronegative newborn calves decreases clinical signs in a challenge trial. However, the situation is complicated by the potential for establishment of seronegative latent carriers in calves with specific maternal antibodies through field virus infection as well as through vaccination with modified-live vaccines. In Europe, the use of conventional vaccines is prohibited in some countries. Further, in countries with existing eradication programmes, regulations regarding vaccination need to be considered.
Vaccines against the major bacterial pathogens involved in bovine respiratory disease (Pasteurella multocida, Mannheimia haemolytica, Histophilus somni) can decrease clinical signs in challenge models but are rarely tested in monovalent form in field trials. Aubry et al. were unable to identify any decrease in treatments for respiratory disease in young dairy calves vaccinated with a modified-live Mannheimia haemolytica and Pasteurella multocida vaccine.
Qualified personnel monitored the calves morning and evening, and more frequently if deemed necessary. A veterinarian examined all calves on a daily basis until D10, and three to four times a week thereafter throughout the experimental period. When the general health condition of the calves was negatively affected, the frequency of examination was increased. A clinical scoring system was developed, modified after Hägglund et al., and is presented in Table 1. An overall clinical score was calculated by summing up the separate scores from the clinical registrations. The peak outbreak was defined as the day with the highest number of clinically affected calves.
Pre-term birth children receive intravenous palivizumab to prevent RSV infection. The F-protein epitope recognised by palivizumab seems to be conserved between human and bovine RSV as palivizumab also recognises the F protein of bovine RSV (data not shown). Therefore, like palivizumab, bIgG might be able to prevent infection with hRSV. To this aim GFP-renilla-RSV was pre-incubated with bIgG, IVIg or palivizumab and added to HEp2 cells. After 18–24 hours incubation, cells were harvested and analysed for GFP expression by flow cytometry. Both IVIg and bIgG dose-dependently neutralised RSV, although 6.4 times more bIgG compared to IVIg was needed to inhibit HEp2 cell infection by RSV (IC50: 64 and 10 µg/ml, respectively) (Figure 6B).
HBoV-IgM antibodies were determined by a commercially available immunoglobulin M (IgM) enzyme-linked immunosorbent assay supplied by (Dako, Glostrup, Denmark) for the quantitative determination of IgM antibodies to HBoV in serum. Briefly: serum samples diluted 1:200 in phosphate buffer saline (PBS) and 0.05% Tween (PBST) were applied in duplicate into wells of plates coated with goat anti-human IgM for 60 min at room temperature. After being rinsed 5 times with PBST, biotinylated HBoV viral like particles (VLPs) were applied at a concentration of 25 ng/well and incubated for 45 min at 37°C. Bound antigen was visualized by using horseradish peroxidase-conjugated streptavidin at 1:12,000 in PBST plus 0.5% bovine serum albumin for 45 min at 37°C, followed by o-phenylenediamine dihydrochloride and H2O2 for 15 min at 37°C. The reaction was stopped after 10 min with 0.5 M H2SO4, and the absorbance at 492 nm were recorded. Cut off absorbance for negative and positive IgM ELISA results were 0.136 and 0.167, respectively.
Nasopharyngeal aspirates were collected from patients and control group according to Svensson et al.,. Sterile normal saline solution was instilled in one nostril while occluding the other nostril, using a sterile blunt-tipped disposable syringe. Then the patient was instructed to forcibly exhale through the lavaged side into a sterile specimen cup. The sequence was then repeated in the other side of the nose. NPA specimens were examined microbiologically immediately and part of the specimens was stored in aliquots at -70°C for PCR. Two ml blood samples from both patients and control were collected into vacutainer, centrifuged and serum was separated and stored at - 20°C for HBoV-IgM antibodies by ELISA.
Bovine sera were treated with receptor-destroying enzyme overnight at 37°C and then heat inactivated at 56°C for 30 min. Hemagglutination inhibition (HI) assays were run with 0.5% packed turkey red blood cells as described in the WHO’s Manual on Animal Influenza Diagnosis and Surveillance (36). Bovine sera were a gift from the SD State University Veterinary Diagnostic Laboratory and represented samples from five states (South Dakota, Vermont, Pennsylvania, Idaho, and California) submitted for unrelated diagnostic testing.
All influenza A, B, and C reference virus antigens and antisera were obtained from Biodefense and Emerging Infections Research Resources Repository (BEI Resources). AGID antigens for swine C/OK virus, bovine influenza C-like virus, human influenza virus C/JHB, and human influenza virus C/Taylor were prepared according to the protocol of WHO and the World Organization for Animal Health (OIE). Supernatants from uninfected cell cultures (MDCK and HRT-18G) were prepared as mock controls using the same procedures as those used for production of viral antigens. Rabbit polyclonal antibody against swine C/OK virus was prepared using purified C/OK virus antigens. AGID plates were prepared according to the standard procedure, and assays were performed in triplicate according to WHO/OIE protocol (36). Similar concentrations of viral antigens for all tested strains (approximately 12 log2 HA units per 0.025 ml) were used in parallel with mock controls for antigen recognition by antisera in AGID with two different dilutions (neat and 1:2).
bIgG was purified from commercially available bovine colostrum (Colostrum 35% IgG, Reflex Nutrition, Bristol, UK) using an AFFI-T™ column (Kem-en-Tec) followed by a protein G column (5 ml; Amersham). bIgG was eluted with 0.1 M glycine-HCl pH 2.7 elution buffer and neutralised with 1 M Tris-HCl pH 9.0, followed by dialysation against PBS and sterilisation (0.2 µm filter). Fresh milk and colostrum samples were supplied by FrieslandCampina (the Netherlands).
Bovine respiratory disease (BRD) affects the lower respiratory tract of cattle, causing high mortality and carcasses of lower quality. The syndrome has a multifactorial etiology, including infectious agents, host and environmental factors, with particular emphasis on transport stress. The latter is indeed responsible for physiological changes that favor pathogen proliferation and invasion of tissues by opportunistic pathogens. Viruses and stress-related behavior interfere with the mucociliary clearance of the respiratory tract and dysregulate the tracheal antimicrobial peptides of the innate defenses, allowing opportunistic bacteria to cause pulmonary infections. Infectious agents of BRD include both viral and bacterial agents such as bovine herpesvirus type 1 (BoHV-1), bovine adenovirus (BAdV), bovine viral diarrhea virus (BVDV), bovine coronavirus (BCoV), bovine respiratory syncytial virus (BRSV), bovine parainfluenza virus (BPiV), Pasteurella multocida, Mannheimia haemolytica, Histophilus somni and Mycoplasma bovis.
It has been shown that, to minimize the incidence of transport-related respiratory disease, antibiotics and vaccines are widely used both before and after transport. However, the data on the effectiveness of these preventative methods are conflicting. The hypothesis of this work was that there would be a change in the nasal microbiota, with an increase in the prevalence of bacteria and virus involved in BRD, in beef steers subjected to long distance transportation and not treated before the journey.
Despite the high number of trucks transporting livestock from North Europe to Italy, to the authors’ knowledge, there are no data available in Italy regarding the potential associations between long-distance transport and the onset of BRD after feedlot arrival. Consequently, the aim of this pilot study was to document the prevalence of the multiple pathogens involved in BRD after a long-distance travel from France to southern Italy through investigation of the nasal microbiota.
Bovine kidney cells (MDBK/NBL-1; ATCC® CCL-22™) were cultured at 37 °C with 5% CO2, in DMEM (Fisher Scientific, Loughborough, UK) supplemented with 8% horse serum. Virus isolation and determination of the median of tissue culture infective dose were performed on MDBK cells. Virus isolation was performed as follows: The three nasal swabs, positive for BPIV3, were filtrated through a 0.22 μm filter (Millipore, Milford, MA, USA) and inoculated to a monolayer culture of MDBK cells cultured in Dulbecco’s modified eagle medium (DMEM, Fisher Scientific, Loughborough, UK) supplemented with 8% horse serum (Fisher Scientific, Loughborough, UK). MDBK cells were maintained at 37 °C in an atmosphere of 5% CO2. The cytopathic effect (CPE) was examined daily. The storage solution was exposed to a ten-fold dilution and filtered with a 0.22 μm filter. Then, the filtrate was inoculated into MDBK cells for 1 h. Finally, the culture medium was replaced with DMEM containing 2% horse serum. MDBK cells inoculated with filtrate were cultured in an incubator continually for 72 h. The propagation of the virus was performed three times.
Bovine respiratory disease (BRD) incorporates all possible respiratory diseases in cattle and is characterised by abnormal clinical signs of the respiratory tract. Bovine respiratory disease refers to bacterial bronchopneumonia that may be complicated by previous, or concurrent, viral or Mycoplasma infection. The principal viruses involved in BRD include bovine herpesvirus 1 (BHV-1), bovine respiratory syncytial virus (BRSV), bovine parainfluenza virus type 3 (PI-3) and bovine viral diarrhoea virus (BVDV). Despite advances in veterinary medicine, animal husbandry, and animal welfare, respiratory disease among dairy cattle continues to be a major problem in the dairy industry. In addition to enzootic calf pneumonia, outbreaks of respiratory disease in adult animals can have devastating economic outcomes for dairy owners.
Many studies have been performed to detect animal-level risk factors for respiratory disease in young calves, whereas the literature concerning BRD in adult dairy cattle is deficient. In adult dairy cattle, respiratory disease is less important than mastitis, lameness, or reproductive disorders as a cause of morbidity. According to the Annual Report of the Estonian Animal Recording Centre (EARC, 2009), BRD was the reason for culling dairy cows in 0.7% of cases. According to our experience, in most herds BRD occurs as a sporadic disease in adult dairy cattle. However, epidemic outbreaks occur with high morbidity accompanied with dramatic economic losses due to medication use and discarded milk, as well as cow fatalities.
The subclinical course of BHV-1 infection has been observed after the introduction of the virus to a naive herd, however high morbidity of BHV-1 outbreaks involving respiratory disease symptoms (lethargy, coughing, conjunctivitis and oculonasal discharge) was seen on a number of occasions. Outbreaks of severe respiratory disease due to bovine respiratory syncytial virus (BRSV) have been observed in dairy herds throughout Sweden, where adult cattle were most severely affected. Risk factors associated with acute bovine respiratory disease, especially with BRSV outbreaks, were larger herd size, as well as the type of the production with a higher risk in dairy herds compared to beef herds. Acute BRD has been found to occur mainly during cold months, with an epidemic peak in December. Despite the multifactorial nature of BRD, only limited research data is available on herd management-related risk factors for respiratory disease in adult dairy cattle.
Poor fertility is the leading cause of culling cows in Estonia (EACR, 2009). Problems associated with reduced fertility in dairy cattle are related to: diseases of the reproductive tract of the cow, bull fertility, breeding management, and the environment, as well as nutrition. Several infectious diseases are related to abortion in cattle, and BHV-1, BVDV and Neospora caninum are often diagnosed as causes of abortion in cattle world-wide. However, field studies estimating the effect of BHV-1 on herd level reproductive performance have given contrary results. Previous studies found no association between the proportion of calves with antibodies against BVDV or BHV-1 virus and reproductive performance in beef herds. A somewhat higher mean open days period was found in cows that were serologically positive for BHV-1 than in seronegative dairy cows, however no decrease in reproduction performance was found to occur during an outbreak of BHV-1 in a dairy herd. To our knowledge no epidemiological studies have been published to identify and quantify the association between herd BHV-1 seroprevalence and farm-level reproductive performance in dairy cattle.
The objective of this study was to ascertain the associations between herd BHV-1 seroprevalence and the occurrence of acute respiratory disease and reproductive performance in adult dairy cattle. The association between management-related factors and higher BRD occurrence was also estimated.
Bovine respiratory syncytial virus (BRSV) is an economically significant pathogen in cattle production, as it is one of the most important causes of lower respiratory tract infections in calves. In dairy cattle, BRSV infection usually occurs in young calves aged between 2 weeks and 9 months. Adult animals with subclinical infection are the main source of infection, since reinfections are common in the herds [1, 4, 5].
BRSV, bovine herpesvirus 1 (BoHV-1), bovine viral diarrhea virus (BVDV) and bovine parainfluenza type-3 (PI-3) are considered primary agents involved in the bovine respiratory complex. Additionally, secondary infection by Pasteurella multocida, Histophilus somni and mycoplasmas contribute to the aggravation of the disease. Clinical signs are characterized by respiratory symptoms, initially with moderated intensity, such as nasal and ocular discharges which can be aggravated leading to pneumonia. However, mainly in calves, an acute and severe onset is also observed, due to maternal antibodies not effectively protect against BRSV infection.
Considering the high prevalence of the disease, several studies determined risk factors involved in the epidemiology of BRSV. In Europe, risk factors were mainly attributed to herd size, herd density, purchasing of new animals, geographic location of the farms, herd type and concomitant BVDV infection [7–11]. Similar studies have also been performed in some Latin American countries and they showed that most of the animals probably have already been exposed to the virus with consequent high BRSV prevalence in cattle herds. In these countries, herd size, age group, presence of bordering farms, herd type and geographic location of the farms were the main risk factors associated with BRSV infection [12–16].
In Brazil, BRSV was first diagnosed in calves in the state of Rio Grande do Sul and some studies have shown that BRSV infection is widespread in Southern and Southeastern Brazil, with high serological prevalence rates [18–20]. Nevertheless, research has not been conducted in order to verify possible risk factors involved in BRSV epidemiology. Due to this, the current study aimed to determine antibody prevalence against BRSV and investigate some risk factors associated with BRSV seroprevalence in herds of an important milk producing region in São Paulo State, Brazil.
All animal procedures were conducted in strict accordance with federal and institutional guidelines and were approved by the Kansas State University Institutional Animal Care and Use Committee. The animal care protocol included provisions for a humane endpoint as determined by the discretion of the attending clinical veterinarian. Methods to minimize pain and distress included the avoidance of prolonged restraint and the inclusion of euthanasia as an intervention strategy.
A total of forty-three, mixed-gender (n = 21 males; n = 22 females) Holstein calves were purchased from two dairy farms, one in southern Nebraska (n = 37) and one in central KS (n = 6), and were enrolled in the study at birth. Calves were randomly assigned to the VAD or VAS treatment group. All calves were prevented suckling from their dams, and instead received a first feeding of colostrum replacer within 4 h of birth. Each animal received 375 g of fractionated colostrum replacer (Milk Products, Chilton, WI) reconstituted in 1.9 L of water at approximately 40 °C. The colostrum replacer contained 150 g of bovine globulin protein concentrated from colostral whey and was essentially devoid of all fat-soluble vitamins A, D3, and E. Vitamins D3 (150,000 IU of cholecalciferol/dose) and E (1,500 IU alpha-tocopheral/dose) were added back to the colostrum replacer for all calves. VA (150,000 IU retinyl palmitate) was added back to the VAS treatment group. VA was omitted from the colostrum replacer for the VAD calves. Animals were then placed on a VAS or VAD milk replacer diet for the remainder of the study (Milk Products, Chilton, WI). Calves were transported to the Large Animal Research Center at Kansas State University at 3–4 days of age and housed in groups of 2–3 calves per pen on pine chip bedding. Calves were bottle-fed three times per day (~8 hours apart) until 3 weeks of age, then twice per day (~12 hours apart). The milk replacer consisted of 21% crude protein and 20% fat, and was fed at a rate of 1.5 lbs/day and 14% solids. VAS calves received 45,000 IU VA (retinyl palmitate) per day. VAD animals received the same milk replacer formulation without VA. Calves were also provided ab libitum access to calf starter pellets (18% crude protein, 8% ADF) starting at ~2 weeks of age. Starter grain was formulated without added VA (VAD calves) or with 1820 IU/lb (VAS calves).
Serum retinol levels were monitored weekly. Samples were submitted to the Iowa State University Veterinary Diagnostic Laboratory for evaluation. At 6 weeks of age, animals were divided into 4 groups: 1) VAS, no vaccine (n = 6; 3 females and 3 males); 2) VAS, BRSV-NP vaccine (n = 13; 7 males and 6 females); 3) VAD, no vaccine (n = 6, 2 males and 4 females); 4) VAD, BRSV-NP vaccine (n = 12; 5 males and 7 females). Calves were vaccinated intranasally with 145 mg BRSV-F/G loaded CPTEG:CPH nanoparticles (~2 mg recombinant F and G proteins) with 2 mg soluble recombinant F and G proteins. The vaccine was suspended in 5 mL of sterile saline, with 2.5 mL delivered into each nostril. The calf was restrained and its head was tilted up, then the vaccine was administered into the nose using a syringe fitted with a 2-inch nasal cannula, equipped with a plastic depth control ring. Following vaccination, immune responses were monitored weekly in the serum, peripheral blood, and upper (nasal fluid collection) and lower (bronchoalveolar lavage fluid collection) respiratory tract. Six calves (VAS, n = 3, all calves were male; VAD, n = 3, 2 females and 1 male) were sacrificed prior to challenge and samples of lung and liver tissues were collected to verify retinol concentrations and to serve as control tissues for immunology and gene expression studies.
All experimental procedures were performed with approval and under the guidelines of the US Meat Animal Research Center (USMARC) Institutional Animal Care and Use Committee (IACUC approval numbers 5438–31,000–082-04 (24) and 3040–32,000–031-07 (5)).
To determine the impact of VAD on the response to mucosal vaccination and subsequent RSV challenge, we first established two groups of calves with differing levels of serum and liver retinol. Calves are born with low VA levels and colostrum is a major source of VA and other fat-soluble micronutrients37. Therefore, all calves received fractionated colostrum replacer with or without VA restored, and were placed on a VAS or VAD milk replacer diet. Serum retinol levels were evaluated weekly, starting after calves were on the differential diets for 1 week. As shown in Fig. 1A, all animals had low serum retinol levels at week 1, but these levels increased in the VAS group, reaching normal serum retinol concentrations by 5–6 weeks of age. The normal range for serum retinol in juvenile calves (30–300 days) is 0.25–0.33 ppm38. Plasma VA levels are tightly regulated by the liver, and therefore not optimal for determining VA status. To confirm VA status in our two treatment groups, liver samples were collected at the time of necropsy. The normal range for liver retinol in juvenile calves is 75–130 ppm38. As seen in Fig. 1B, calves in the VAD treatment group had below normal retinol stores in the liver at the time of necropsy, while VAS calves had normal liver stores.
No additional information is available for this paper.
Bovine respiratory disease complex (BRDC) is a global problem causing severe economic losses to the cattle farming industry through mortality, loss of production, and treatment costs [1, 2]. It has a complex etiology that involves various pathogens, host factors, and environmental factors. Viruses such as bovine herpes 1 virus (BoHV-1, parainfluenza virus 3 (PBIV-3), bovine respiratory syncytial Virus (BRSV), respiratory bovine coronavirus (BoCoV) and bovine viral diarrhoea virus (BVDV) in conjunction with stress factors have been implicated as causes of respiratory tract infections of cattle by immunosuppression and damage to the respiratory epithelium. A primary viral infection can be followed by an opportunistic secondary infection with bacteria like Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, or Trueperella pyogenes [2, 4, 5], but these bacteria could also act as primary pathogen. In addition it has become increasingly clear that Mycoplasmas are important contributors to BRD, either as primary pathogens or in co-infection [2, 6–9]. M. bovis is the best known Mycoplasma species causing respiratory disease [4, 7], but also M. dispar and M. bovirhinis have been associated with BRD [2, 9–11]. M. bovis has not only been identified as a primary or opportunistic pathogen in BRD in beef cattle worldwide, but it has also been implicated in other clinical manifestations in cattle, such as mastitis, otitis, arthritis, and reproductive disorders. M. bovirhinis and M. dispar are regularly isolated from the nasal cavity of cattle with respiratory disease and are usually regarded as an opportunistic pathogen in respiratory diseases [7, 12].
Bacteriological, serological and histopathological examinations are important tools to detect particular animal-carriers of Mycoplasma, however, these assays are time-consuming, insensitive and can give false positive results. Bronchoalveolar lavage fluid (BALF) from calves with BRD may contain various potential pathogens, but additional antibiotic use in the affected herds can inhibit cultivation and thereby can cause false-negative test results. In BRD, differential diagnosis of these pathogens with rapid turnaround time procedure is essential to implement appropriate treatment and intervention measures in a timely manner. Rapid detection of these pathogens at the early stage of outbreak can contribute substantially to minimize the spread of infection and increase treatment efficiency. Today quick, highly sensitive and species-specific PCRs are used in the diagnosis of Mycoplasma-associated diseases for M. dispar [14, 15], M. bovis [4, 16] and M. bovirhinis in BALF or nasal swabs. Combining a 16S Ribosomal DNA PCR with denaturing gradient gel electrophoresis fingerprinting (PCR/DGGE) enabled the simultaneous detection of mixed Mycoplasma populations, however information about the detection limit in clinical samples is limited. Additionally, a DNA microarray assay was developed for the parallel detection of 37 Mycoplasma species, in which species-specific probes derived from the 23S rRNA and tuf genes were used for species differentiation.
Multiplex real-time PCR could be a promising and practical approach to speed up the differential diagnosis from 1 to 2 weeks for traditional culture to 24 h, with limited expenses. This will make diagnostic testing more accessible for veterinary practitioners and thereby improve BRD diagnosis. This report describes the RespoCheck triplex PCR developed by Central Veterinary Institute (CVI, Lelystad, The Netherlands) for detection of three Mycoplasma species.
Bovine respiratory disease (BRD) is the leading cause of morbidity and mortality for all production classes of cattle and calves in the U.S., causing losses to the cattle industry in excess of $1 billion dollars annually [1, 2]. Multiple etiologies, including both viral and bacterial, contribute to BRD. Those generally accepted to be important contributors to BRD include the viral pathogens bovine herpesvirus-1 (BHV-1), bovine viral diarrhea virus types 1 and 2 (BVDV), bovine respiratory syncytial virus (BRSV) and parainfluenza-3 virus (PI3); and the bacteria Mannheimia haemolytica, Pasteurella multocida, Histophilus somni and Mycoplasma bovis [2, 4]. BRD is frequently initiated by a viral infection that disrupts local defenses and/or causes immune suppression, allowing opportunistic bacterial pathogens that are in healthy animals as normal nasophayngeal commensals to proliferate and infect the lungs [2, 4]. Superimposed environmental or management related stress (such as adverse weather, shipping, and commingling) can further suppress the host immune system, increase pathogen exposure, and may be important co-requisites in many BRD outbreaks. Although vaccines and antibiotic treatments are readily available to prevent and treat infection caused by common BRD pathogens, the incidence of disease remains high.
In recent years, bovine coronavirus (BCV) has been implicated as an important contributor to BRD. Although initially described as being associated with calf diarrhea, BCV has been found to infect the upper and lower respiratory tract and has been isolated from pneumonic lungs alone or in combination with other respiratory pathogens [7–12]. In addition, results of multiple studies indicate that groups of cattle with high titers of serum antibodies to BCV at the time of feedlot entry are less likely to shed BCV and develop BRD than those with low anti-BCV serum antibody titers [7, 13–15]. Taken together, it appears that BCV contributes to feedlot BRD, and high titers of serum anti-BCV antibodies associate with reduced risk of BCV infection and disease. However, it remains unknown whether the serum antibodies themselves are immune correlates of protection, or whether they simply reflect prior exposure to the virus.
The relationship between BCV and BRD in pre-weaned beef calves has not been comprehensively evaluated. Though BCV is frequently detected in nasal swabs from nursing calves with BRD, subclinical BCV infections are also common in young dairy calves, even in the presence of relatively high anti-BCV antibody titers [16, 17]. These results raise questions about the association between anti-BCV antibody titers and BCV shedding with the risk of developing BRD in nursing dairy calves. Similarly, in a 2014 study, our group sampled four research herds (n = 890) at predefined times from birth through their fifth week in the feedlot. This study revealed that the herds in which BCV was detected in nasal sections during the pre-weaning period also had the highest incidence of pre-weaning BRD; however, nasal swabs were not collected at the time of treatment to diagnose the pathogens associated with those pre-weaning BRD cases. This study also reported that serum anti-BCV antibody abundance did not correlate with BCV shedding prior to weaning. Thus, while mounting evidence suggests that anti-BCV antibodies protect weaned feedlot cattle from BRD associated with BCV infection, the relationship between humoral immunity to BCV, virus shedding, and the risk for developing BRD in nursing calves remains unclear. This represents a major obstacle in the development of effective control strategies to reduce the impact of BCV-related respiratory disease in cattle, which is significant given that there are currently no licensed BCV vaccines in the United States to aid in the prevention of BRD.
To address this knowledge gap, the present study serially sampled 817 calves from three herds of beef cattle from birth through weaning to determine whether shedding of BCV is associated with BRD and whether levels of anti-BCV serum antibodies associate with BCV shedding or BRD incidence in pre-weaned beef calves. Sequence analysis of the virus strain(s) circulating in each herd and the prevalence of common opportunistic bacterial pathogens (M. haemolytica, P. multocida, H. somni and Mycoplasma bovis) in the upper respiratory tract of sick and apparently healthy cattle were also evaluated to account for potentially confounding factors that could influence BRD development in these populations.
Along with equine rhinitis virus (ERV) and foot and mouth disease virus (FMDV), bovine rhinitis A and B viruses (BRAV and BRBV, respectively) are species in the genus Aphthovirus, family Picornaviridae. Two serotypes of BRAV have been identified, BRAV1 and BRAV2, while BRBV consists of a single serotype. The BRAV1 strain SD-1 was isolated in Germany in 1962 from nasal secretions from a calf with rhinitis. Additional BRAV1 strains were subsequently isolated from both healthy and diseased bovines in England, Japan, Italy and the U.S. and shown to cross react in serum neutralization assays [3–6]. The sole BRBV isolate EC-11 was isolated in England in 1964 by Reed from the lung of a specific pathogen free calf with respiratory disease. Likewise, BRAV2 consists of a single specimen, strain H-1, isolated from an outbreak of respiratory disease in cattle in 1984. Despite numerous studies on bovine rhinitis viruses (BRV) in the 1960’s through mid-1980’s, little work has been published on their epidemiology and ecology the past several decades.
Bovine respiratory disease complex (BRDC) is the most economically significant disease of the cattle industry, leading to losses due to mortality, morbidity, treatment costs and feed inefficiency in excess of $750 million dollars per year in the U.S. alone. BRDC has a multifactorial etiology involving a variety of bacteria and viruses in addition to host and environmental factors. Numerous commercial vaccines including both killed and attenuated live bacteria are available. Viruses commonly included in commercial vaccine include bovine viral diarrhea virus (BVDV), bovine herpes virus 1 (BHV1), parainfluenza virus 3 (PI3) and bovine respiratory syncytial virus (BRSV). Despite their widespread use, BRDC incidence has increased over the past 20 years. BRDC pathogenesis often involves a primary viral infection which damages respiratory mucosa and alters host immune responses leading to secondary bacterial pneumonia caused by commensal bacteria already present in the respiratory tract.
Both BRAV and BRBV are established but rarely studied etiologic agents of BRDC. Experimental inoculation of calves with BRAV1 via intranasal (IN) or intratracheal (IT) routes, either singly or in combination, resulted in variable clinical signs of respiratory disease and histologic lesions consistent with pneumonia. BRAV1 was also recovered from nasal swabs of IN inoculated animals and all animals inoculated or exposed by contact seroconverted to BRAV1 by day seven post inoculation. A similar experiment using a different BRAV1 strain (RS 3x) and colostrum deprived calves failed to reproduce clinical disease but was successful in isolating BRAV1 from nasal swabs post inoculation and found histological lesions of focal rhinitis and a neutralizing antibody response in all inoculated calves. BRBV pathogenesis was investigated using intranasal inoculation of gnotobiotic calves. Clinical signs including fever, nasal discharge and increased respiration rate were observed. Foci of epithelial necrosis were observed histologically in the turbinates and trachea and interstitial pneumonia was evident in the lungs. Virus was isolated from multiple tissues and was neutralized by convalescent antiserum. In addition to controlled studies, numerous investigations of acute respiratory disease in cattle resulted in the isolation of bovine rhinitis viruses where paired acute and convalescent sera suggested a causative role for bovine rhinitis virus.
Metagenomic sequencing on nasal swabs obtained from BRDC diagnostic submissions were performed to survey viruses present. Contigs with high identity to BRAV2 and BRBV were identified in one swab. To further our understanding of the epidemiology and ecology of bovine rhinitis viruses in BRDC, a more comprehensive survey was performed.
Bovine respiratory disease complex (BRDC), a multi-factorial disease, is an economically important health problem of cattle worldwide. The disease is commonly referred to as “Shipping fever” and causes an increase in morbidity mortality rates. The multiple factors that cause BRDC include stress, infectious agents, immunity, and housing conditions. The infectious agents associated with BRDC include viruses, bacteria, and mycoplasmas. While most acute infections with uncomplicated infectious agents are sub-clinical, they can cause respiratory disease characterized by a cough, fever, and nasal discharge. Mixed infections with two or more infectious agents are thought to contribute to BRDC. The primary viral infectious pathogens that cause BRDC are bovine parainfluenza virus 3 (BPIV3), bovine respiratory syncytial virus (BRSV), bovine viral diarrhea virus (BVDV), bovine alphaherpesvirus 1 (BHV-1), bovine coronavirus (BCV), and so forth.
Bovine parainfluenza virus type 3 (BPIV3) was one of the most important viruses associated with BRDC in cattle. It was first isolated in 1959 and first identified in cases of BRDC. BPIV3 is an enveloped, non-segmented negative-strand RNA virus within the genus Respirovirus. BPIV3 induces respiratory tract damage and immunosuppression. More severe secondary bacterial and mycoplasma infections are caused in susceptible animals in instances of high stress, such as transportation and feedlot situations.
Up to now, based on phylogenetic analysis, BPIV3 has been divided into three genotypes: Genotype A, genotype B, and genotype C. Multiple BPIV3 genotype A strains have been isolated in USA, China, Argentina, and Japan. Genotype B was initially identified in Australia. Isolation of BPIV3 genotype C, first identified in China, has also been conducted in South Korea, Japan, Argentina, and USA. A high seropositivity rate for BPIV3 in dairy cattle indicated that a high level of BPIV3 infections occurs. Many efforts have been made focusing on the prevention and control of BRDC in order to reduce production losses in the livestock industry.
Here, we describe the cell culture isolation and genomic sequencing of a BPIV3 genotype A strain isolated from cattle in China. Although BPIV3 is endemic in cattle, little is known about the pathogenesis of this virus and information regarding antigenic variation owing to the genetic variability is rare. The phylogenetic comparison of our isolated strain with strains previously characterized in China indicated the presence of divergent strains of genotype A circulating in the country. The diversity of BPIV3 in China seems to mirror the diversity of this virus, which is observed in the USA. In addition, the full characterization of our BPIV3 genotype A strain will lend support to molecular diagnoses and to future studies aimed at developing an efficient vaccine against multiple viral lineages.
Bovine respiratory disease complex (BRDC) is a major cause of economic losses in the cattle industry worldwide. The most important viral agent include bovine herpesvirus type 1 (BHV-1), bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), and bovine parainfluenza-3 virus (BPI-3V). BRSV, belonging to the genus Pneumovirus within the family Paramyxoviridae, and is one of the most important causes of lower respiratory tract infections in calves; however, adult animals with subclinical infection are the main source of infection, since reinfections are common in the herds. It is highly prevalent in cattle, with a significant economic impact as the most important viral cause of BRDC worldwide. BVDV is a Pestivirus from the family Flaviviridae, which affects the digestive, respiratory, and reproductive systems in different production animals. Clinical signs include pyrexia, diarrhea, reduced production, and highly morbid disease but cause low mortality of infected animals. Infectious bovine rhinotracheitis (IBR) is an important infectious disease of domestic and wild cattle caused by BHV-1. This virus is a member of genus Varicellovirus, which belongs to the Herpesviridae family. Clinical signs infection includes symptoms of inflammatory reactions in respiratory, genital tracts, abortion, and neurological disorders. Betancur et al. found a statistical association between seropositive animals for BHV-1 with respect sex and age in Colombia, while Ochoa et al. reported higher infection in cows older than 5 years of age. BPI-3V is in the genus Respirovirus of the family Paramyxoviridae, which cause serious economic losses in small and large ruminants. Clinical disease is usually mild, with symptoms of fever, nasal discharge, and cough. Betancur et al. reported a statistical association between seroprevalence values for BPI-3V and age groups.
Aguachica, Rio de Oro, and La Gloria municipalities are located in Cesar department, which, in turn, is located in the Northeast of Colombia, and is very important agricultural and fish raising region, being the dual-purpose cattle husbandry one of the most important agricultural components of the regional economy, with a participation of 8% in the cattle national inventory. According to the National Agricultural Institute, the state has a population of 1,305,984 heads of cattle, being 30% located in the three municipalities.
Information about the prevalence of these viral pathogens is available from several countries in which these diseases have been reported. Nevertheless, there is very little epidemiological information on viral pathogens in cattle, mainly in the Northeast region of Colombia. Therefore, the present study was conducted to estimate the seroprevalence of respiratory viral pathogens in dual-purpose cattle and evaluate risk factors in the municipalities of Aguachica, Rio de Oro, and La Gloria in the department of Cesar.
Cells were infected with PRRSV at 0.5 MOI of in DMEM without serum and other additives and incubated for 4 hours. Then infected cells were washed and fresh medium was added. Cells were treated with 4 µg/ml of LPS purified from Appwt
, or 100 to 1,000 ng/ml of C12-iE-DAP (a NOD1 ligand, InvivoGen, San Diego CA), or 100 to 1,000 ng/ml of L18-MDP (a NOD2 ligand, InvivoGen) for 48 hours. The presence of PRRSV N protein was determined by IFA. The virus titer was determined as described above.
Calf diarrhea has been a major disease that negatively affects the cattle industry. The economic impact caused by this condition is significant although many new intervention strategies (e.g., vaccine, medications, and herd management) have been developed and implemented to minimize the economic loss. Persistence of this significant problem in the field may be attributed to the multifactorial nature of calf diarrhea including permutations of infectious diseases, a failure to clearly understand the disease ecology, poor environmental hygiene, and biased epidemiological data. Genetic diversity, continuous evolution, emerging pathogens, and/or environmental ubiquity of pathogens are factors that hinder effective control of the disease. Therefore, the genetic evolution of RNA viral pathogens such as BRV, BCoV, BVDV, BToV, BNoV, and Nebovirus should be kept in mind and monitored with regular genomic sequence updates. Non-group A BRV might be considered for future studies to increase the detection range of calf enteric pathogens. Emerging viruses should be regularly monitored for the evaluation of vaccines against calf enteric pathogens. Clinical significance of caliciviruses (BNoV and Nebovirus) must be carefully assessed to better control calf diarrhea in the future.
The use of highly sensitive diagnostic tests has increased the detection frequency of pathogens that were previously neglected. Therefore, optimized and appropriate diagnostic methods or platforms should be employed for detecting target pathogens in an accurate and timely manner with a minimum testing outcome bias. Currently, real-time PCR-based techniques are widely implemented in many veterinary diagnostic laboratories. These methods are highly accurate and provide high throughput performance but sometimes might overestimate the significance of pathogens detected in cases of calf diarrhea. The pros and cons of diagnostic test results and their overall interpretation must therefore be cautiously evaluated by referring clinical history from practitioner when the causative etiology is being determined.
Non-infectious risk factors have frequently been neglected by cattle producers, and also be considered equally important as infectious factors because the newborn animals are vulnerable to environmental stresses. The management and control of calf diarrhea before an outbreak is more cost-efficient than treating sick animals after the outbreak occurs. Although many enteric pathogens are involved in calf diarrhea, infection and transmission is accomplished via a fecal-oral route. Care must be thus taken to prevent pathogen transmission. Advice from professional consultants such as veterinarians and nutritionists is necessary to obtain an accurate diagnosis and control or manage risk factors associated with calf diarrhea in modernized large production systems.
In summary, the effective control of calf diarrhea should be based on three major points. First, a clear understanding of pathogen characteristics (e.g., mechanism underlying pathogenicity, prevalence in the field, and genetic evolution) is required. Second, advantages and disadvantages of various diagnostic methods and their application to diagnostic investigation along with clinical history should be considered. Finally, proper cow-calf management is necessary for disease prevention and control.
Bovine Respiratory Disease (BRD) is a multifactorial disease characteristic of a viral-bacterial synergistic infection with predisposition from environmental stressors. The disease constitutes a major source of economic loss through mortality, clinical disease and the associated treatments and long lasting reduced growth performance of infected young stock [2, 3]. The annual cost of BRD is estimated at $1billion in the USA, with preventative measures contributing a further $3billion [4, 5]. Vaccines are commonly used for controlling BRD viral pathogens, but despite seasonal vaccination, animals can become infected with each new outbreak, maintaining the infection within the population. The viral pathogens associated with BRD [Bovine Parainfluenza Virus type-3 (BPI3V), Bovine Respiratory Syncytial Virus, Bovine Viral Diarrhoea Virus and Bovine Herpes Virus-1] impair immune responses in infected animals and damage the respiratory tract allowing the establishment of secondary infections, that may develop further into bacterial pneumonia. However, vaccinated animals can successfully clear viral infections faster than non-vaccinated animals through immune memory response, reducing the associated viral tissue damage or impairment of immune functions preventing the establishment of secondary bacterial and mycoplasma infections. During disease outbreaks, identification of unvaccinated animals at the early stages of infection could provide a window for effective treatment and facilitate the removal of animals that pose a greater risk of becoming infected and transmitting the infection to more susceptible juvenile stock. Furthermore, halting viral disease progression to more severe and costly secondary bacterial infections through the identification of vaccine failure animals during infection outbreaks would reduce the level of antibiotic use in the agricultural industry.
The only definitive method for successfully identifying vaccinated animals in the presence of an active viral infection is to determine the rate of viral shedding by virus isolation, cytokine/interleukin profiling or virus neutralization assay. These types of analysis require repeated sampling, a period for seroconversion and are expensive compared to serology based ELISA, and are therefore not routinely employed during endemic viral infection outbreaks. Differentiating infected from vaccinated animals (DIVA) marker vaccines (e.g. a modified wild type virus with a gene deletion resulting in the absence of a particular diagnostic antigen) can be employed to differentiate vaccine antibody responses from that of wild type virus. Companion serology based tests rely on seroconversion, and upon exposure to wild type virus the antibody response to DIVA vaccines will be masked by that of the wild type virus. Vaccine DIVA functionality is often limited to large viruses with increased potential for gene deletion and removal of redundant expressed antigens. Therefore, for viruses with small genomes such as paramyxoviruses (e.g. BPI3V and Bovine Respiratory Syncytial Virus of the BRD complex) where gene deletion of neutralizing antigens may reduce vaccine efficacy, alternative approaches are required to provide DIVA functionality. One approach is to design molecular DIVA vaccines that contain a marker nucleotide sequence differing from the wild type virus that can be employed in combination with PCR-based molecular diagnostics to differentiate between vaccine and wild virus strains [10, 11]. Successful differentiation of vaccinated from non-vaccinated animals using this technique requires concurrent vaccination and infection [12, 13], with a narrow diagnostic window post-infection for detection of DIVA vaccine and viral genetic material. Furthermore, detection of vaccine genetic material only demonstrates exposure to the vaccine and not the successful generation of immune protection, limiting functionality in assessment of herd level immunity. Consequently, there is a clear need for alternative diagnostic methods that can assess efficacy of vaccines and vaccination status of animals exposed to BRD viral pathogens at the early stages of infection prior to seroconversion and which do not require repeated sampling. Additionally, the lower initial exposure rates to viral infections in field settings combined with variation in strain nucleotide sequences and short periods of virus secretion highlights the requirement for a DIVA approach with a long diagnostic window which is not strain specific.
A potential approach that can meet these needs is based on the application of metabolomics to identify metabolites or ‘small molecules’ in biological samples that are signatures that correlate or provide some evidence of immune protection. These metabolites are often the end stage products of biological processes and therefore provide an accurate representation of an organism’s homeostatic status at time of sampling [14, 15]. Metabolomic analysis of bio-fluids has provided new insights to the understanding of the patho-physiological processes involved in disease establishment, development and diagnosis [16–19]. Whilst metabolomics has had limited application in the field of veterinary research, several studies have demonstrated the potential of this technique in the prediction of BRD disease outcome, differentiation of stress from viral infection responses, and characteristic of immune responses following vaccination. This study focuses specifically on BPI3V due to its endemnicity within cattle populations and absence of clinical symptoms which still predispose animals to more severe bacterial infections. Due to its small genome and absence of non-redundant proteins suitable for removal in DIVA vaccines, BPI3V is an excellent model for assessing the potential of metabolomics to establish vaccination status in infected animals. The aims of the current study were therefore to assess the performance of Reverse Phase (RP) and Hydrophobic Interaction Liquid Chromatography (HILIC) separation methods for Ultra Performance Liquid Chromatography-Mass Spectrometry (UPLC-MS) metabolomic profiling of bovine plasma and identify plasma metabolomic markers capable of differentiating between vaccinated and non-vaccinated calves following intranasal challenge with BPI3V. This work for the first time reports the metabolomic responses following challenge with BPI3V and demonstrates how the application of metabolomic profiling may help overcome current limitations in DIVA diagnostics by identifying markers capable of differentiating between vaccinated and non-vaccinated animals, and importantly allow the development of better tools to assess the performance of vaccines.