Colostrogenesis: candidate genes for IgG1 transcytosis mechanisms in primary bovine mammary epithelial cells.

Bovine colostrogenesis is distinguished by the specific transfer of IgG1 from the blood to mammary secretions. The process has been shown to be initiated by hormones and occurs during the last weeks of pregnancy when steroid concentrations of estradiol (E2 ) and progesterone (P4 ) are highly elevated. Rodent intestinal uptake of immunoglobulin G is mediated by a receptor termed Fc fragment of IgG, Receptor, Transporter, alpha (FcGRT) and supported by light chain Beta-2-Microglobulin (β2M). We hypothesized that steroid hormone treatments (E2 and P4 ) of bovine mammary epithelial cells in vitro would induce up-regulation of IgG1 transcytosis candidate gene mRNA expression suggesting involvement in IgG1 transcytosis. Two different primary bovine mammary epithelial cell cultures were cultured on plastic and rat tail collagen and treated with hormonal combinations (steroids/lactogenic hormones). Evaluated mRNA components were bLactoferrin (bLf: a control), bFcGRT, β2M, and various small GTPases; the latter components are reported to direct endosomal movements in eukaryotic cells. All tested transcytosis components showed strong expression of mRNA in the cells. Expression of bFcGRT, bRab25 and bRhoB were significantly up-regulated (p < 0.05) by steroid hormones. bRab25 and bRhoB showed increased expression by steroid treatments, but also with lactogenic hormones. Analysis for the oestrogen receptor (ER) mRNA was mostly negative, but 25% of the cultures tested exhibited weak expression, while the progesterone receptor (PR) mRNA was always detected. bRab25 and bRhoB and likely bFcGRT are potential candidate genes for IgG1 transcytosis in bovine mammary cells.

Effects of induced energy deficiency on lactoferrin concentration in milk and the lactoferrin reaction of primary bovine mammary epithelial cells in vitro.

A dietary energy restriction to 49% of total energy requirements was conducted with Red Holstein cows for three weeks in mid-lactation. At the last day of the restriction phase, primary bovine mammary epithelial cells (pbMEC) of eight restriction (RF) and seven control-fed (CF) cows were extracted out of one litre of milk and cultured. In their third passage, an immune challenge with the most prevalent, heat-inactivated mastitis pathogens Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was conducted. Lactoferrin (LF) was determined on gene expression and protein level. An enzyme-linked immunosorbent assay (ELISA) was developed to determine LF in milk samples taken twice weekly throughout the animal trial, beginning on day 20 pp (post-partum) until day 150 pp, in cell culture total protein and in cell culture supernatant. Milk LF increased throughout the lactation and decreased significantly during the induced energy deficiency in the RF group. At the beginning of realimentation, LF concentration increased immediately in the RF group and reached higher levels than before the induced deficit following the upward trend seen in the CF group. Cell culture data revealed higher levels (up to sevenfold up-regulation in gene expression) and significant higher LF protein concentration in the RF compared to the CF group cells. A further emphasized effect was found in E. coli compared to S. aureus exposed cells. The general elevated LF levels in the RF pbMEC group and the further increase owing to the immune challenge indicate an unexpected memory ability of milk-extracted mammary cells that were transposed into in vitro conditions and even displayed in the third passage of cultivation. The study confirms the suitability of the non-invasive milk-extracted pbMEC culture model to monitor the influence of feeding experiments on immunological situations in vivo.

A century of bovine besnoitiosis: an unknown disease re-emerging in Europe.

Bovine besnoitiosis, which is caused by the cyst-forming apicomplexan parasite Besnoitia besnoiti, is a chronic and debilitating vector-borne disease characterized by both cutaneous and systemic manifestations. In Europe, this parasitic disease appeared in a few restricted areas in France and Portugal since the first recorded cases in the beginning of the 20th century. However, at present, the disease is considered to be re-emerging by the European Food Safety Authority due to an increased number of cases and the geographic expansion of besnoitiosis into cattle herds in several European countries. In this review, we will provide an update of the epidemiology and impact of B. besnoiti infection. Strategies to control this parasitic disease will also be discussed.

Chronic bovine besnoitiosis: intra-organ parasite distribution, parasite loads and parasite-associated lesions in subclinical cases.

Bovine besnoitiosis caused by Besnoitia besnoiti is a chronic and debilitating disease. The most characteristic clinical signs of chronic besnoitiosis are visible tissue cysts in the scleral conjunctiva and the vagina, thickened skin and a generally poor body condition. However, many seropositive animals remain subclinically infected, and the role that these animals may play in spreading the disease is not known. The aim of the present study was to assess the intra-organ parasite distribution, the parasite load and the parasite-associated lesions in seropositive but subclinically infected animals. These animals were seropositive at the time of several consecutive samplings, had visible tissue cysts in the past and, at time of slaughter, had detectable specific anti-Besnoitia spp. antibody levels, but they did not show evident clinical signs at culling. Thus, histopathological, immunohistochemical and molecular analyses of several samples from the respiratory tract, reproductive tract, other internal organs and skin from six cows were performed. The tissue cysts were located primarily in the upper respiratory tract, i.e., in the rhinarium and larynx/pharynx (four cows), followed by the distal genital tract (vulva/vagina) and the skin of the neck (three and two cows, respectively, out of the four cows with cysts in the respiratory tract). We were unable to detect any parasites in the two remaining cows. Cysts were associated with a significant non-purulent inflammatory infiltrate consisting predominantly of T lymphocytes and activated monocytes/macrophages in two cows. The parasite burden, estimated by quantitative real-time PCR, was very low. It is noteworthy that the only animal that showed a recent increase in the antibody titre had the highest parasite burden and the most conspicuous inflammatory reaction against the cysts. In conclusion, although these cows no longer displayed any visible signs of besnoitiosis, they remained infected. Therefore, cows without visible signs of disease may still be able to transmit the parasite.

Current attitudes of bovine practitioners, claw-trimmers and farmers in Switzerland to pain and painful interventions in the feet in dairy cattle.

The attitudes of bovine practitioners, claw-trimmers and farmers towards painful therapeutic claw-trimming of dairy cattle were surveyed and differences between the respondents were assessed. A total of 77 farmers and 32 claw-trimmers were interviewed, and 137 bovine practitioners completed an equivalent online survey. No veterinary consultation for common painful interventions in the feet of cattle was reported by 52% of farmers (i.e. procedures in these herds were performed without local anaesthesia). Only ≈30% of practitioners always carried out such interventions under local anaesthesia and, in general, practitioners considered pain reduction to the lowest possible level less important than did farmers. Furthermore, 47% of practitioners and 33% of claw-trimmers, compared to only 11% of farmers, agreed with the statement that the cost of pain management was a major concern for farmers. There was a particular lack of awareness by farmers regarding the obligation to carry out painful therapeutic claw-trimming under analgesia and the application of local anaesthesia during the trimming of sole ulcers was considered reasonable by significantly fewer farmers (41.6%) and claw-trimmers (46.9%), than practitioners (78.6%). Overall, the attitudes of those involved in painful therapeutic claw-trimming contrasted with Swiss national legislation and with farmer opinion on the importance of reducing pain to the lowest level possible.

Improving bovine udder health: a national mastitis control program in the Netherlands

Because of increasing bulk milk somatic cell counts and continuous clinical mastitis problems in a substantial number of herds, a national mastitis control program was started in 2005 to improve udder health in the Netherlands. The program started with founding the Dutch Udder Health Centre (UGCN), which had the task to coordinate the program. The program consisted of 2 parts: a research part and a knowledge-transfer part, which were integrated as much as possible. The knowledge-transfer part comprised 2 communication strategies: a central and a peripheral approach. The central approach was based on educating farmers using comprehensive science-based and rational argumentation about mastitis prevention and included on-farm study group meetings. Comprehensive education materials were developed for farmers that were internally motivated to improve udder health. In the peripheral approach it was tried to motivate farmers to implement certain management measures using nontechnical arguments. Mass media campaigns were used that focused on one single aspect of mastitis prevention. These communication strategies, as well as an integrated approach between various stakeholders and different scientific disciplines were used to reach as many farmers as possible. It should be noted that, because this intervention took place at a national level, no control group was available, as it would be impossible to isolate farmers from all forms of communication for 5 years. Based on several studies executed during and after the program, however, the results suggest that udder health seemed to have improved on a national level during the course of the program from 2005 to 2010. Within a cohort of dairy herds monitored during the program, the prevalence of subclinical mastitis did not change significantly (23.0 in 2004 vs. 22.2 in 2009). The incidence rate of clinical mastitis, however, decreased significantly, from 33.5 to 28.1 quarter cases per 100 cow years at risk. The most important elements of the farmers' mindset toward mastitis control also changed favorably. The simulated costs of mastitis per farm were reduced compared with a situation in which the mastitis would not have changed, with € 400 per year. When this amount is extrapolated to all Dutch farms, the sector as a whole reduced the total costs of mastitis by € 8 million per year. It is difficult to assign the improved udder health completely to the efforts of the program due to the lack of a control group. Nevertheless, investing € 8 million by the Dutch dairy industry in a 5-yr national mastitis control program likely improved udder health and seemed to pay for itself financially.

Bovine Tuberculosis Risk Factors for British Herds Before and After the 2001 Foot-and-Mouth Epidemic: What have we Learned from the TB99 and CCS2005 Studies?

Over the last couple of decades, the UK experienced a substantial increase in the incidence and geographical spread of bovine tuberculosis (TB), in particular since the epidemic of foot-and-mouth disease (FMD) in 2001. The initiation of the Randomized Badger Culling Trial (RBCT) in 1998 in south-west England provided an opportunity for an in-depth collection of questionnaire data (covering farming practices, herd management and husbandry, trading and wildlife activity) from herds having experienced a TB breakdown between 1998 and early 2006 and randomly selected control herds, both within and outside the RBCT (the so-called TB99 and CCS2005 case-control studies). The data collated were split into four separate and comparable substudies related to either the pre-FMD or post-FMD period, which are brought together and discussed here for the first time. The findings suggest that the risk factors associated with TB breakdowns may have changed. Higher Mycobacterium bovis prevalence in badgers following the FMD epidemic may have contributed to the identification of the presence of badgers on a farm as a prominent TB risk factor only post-FMD. The strong emergence of contact/trading TB risk factors post-FMD suggests that the purchasing and movement of cattle, which took place to restock FMD-affected areas after 2001, may have exacerbated the TB problem. Post-FMD analyses also highlighted the potential impact of environmental factors on TB risk. Although no unique and universal solution exists to reduce the transmission of TB to and among British cattle, there is an evidence to suggest that applying the broad principles of biosecurity on farms reduces the risk of infection. However, with trading remaining as an important route of local and long-distance TB transmission, improvements in the detection of infected animals during pre- and post-movement testing should further reduce the geographical spread of the disease.

Bovine Staphylococcus aureus: diagnostic properties of specific media

As accurate discrimination between Staphylococcus (S.) aureus and NSA (non-S. aureus staphylococci) involved in bovine mastitis is essential in terms of clinical prognosis and outcome, the aim of this study was to reevaluate the classical bacteriological procedures to identify these agents. Various media and the coagulase tube test were investigated using 116 strains of S. aureus and 115 of NSA, all isolated from cows with spontaneous intramammary infections (IMI). Furthermore, 25 NSA reference strains were analyzed. The study demonstrated that a few media were appropriate for differentiating S. aureus from NSA, provided that the staphylococci were isolated from bovine IMI. Evaluation of hemolysis further revealed that double or incomplete hemolysis are specific for S. aureus and are, therefore, a decisive diagnostic criterion. For strains showing complete hemolysis, maximal discrimination between S. aureus and NSA was observed by subculturing them on CHROMagar Staph. aureus.

Phenotypic and genotypic identification of streptococci and related bacteria isolated from bovine intramammary infections.

BACKGROUND Streptococcus spp. and other Gram-positive, catalase-negative cocci (PNC) form a large group of microorganisms which can be found in the milk of cows with intramammary infection. The most frequently observed PNC mastitis pathogens (major pathogens) are Streptococcus uberis, Strep. dysgalactiae, and Strep. agalactiae. The remaining PNC include a few minor pathogens and a large nonpathogenic group. Improved methods are needed for the accurate identification and differentiation of PNC. A total of 151 PNC were collected from cows with intramammary infection and conclusively identified by 16S rRNA sequencing as reference method. Nine phenotypic microbiological tests (alpha-hemolysis, CAMP reaction, esculin hydrolysis, growth on kanamycin esculin azide agar and on sodium chloride agar, inulin fermentation, hippurate hydrolysis, leucine aminopeptidase and pyrrolidonyl peptidase activity), multiplex PCR for the three major pathogens (target genes for Strep. uberis, Strep. dysgalactiae and Strep. agalactiae: pauA, 16S rRNA, and sklA3, respectively), and mass spectroscopy using the matrix-assisted laser desorption ionization-time of flight (MALDI-TOF MS) were evaluated for the diagnosis and discrimination of the three clinically most relevant PNC. RESULTS The probability that a strain of Strep. uberis, Strep. dysgalactiae and Strep. agalactiae was correctly identified by combining the results of the 9 phenotypic tests was 92%, 90%, and 100%, respectively. Applying the multiplex PCR, all strains of the three major pathogens were correctly identified and no false positive results occurred. Correct identification was observed for all strains of Strep. uberis and Strep. agalactiae using MALDI-TOF MS. In the case of Strep. dysgalactiae, some variability was observed at the subspecies level, but all strains were allocated to one single cluster. CONCLUSIONS The results of the present study show that reliable identification of the clinically most relevant PNC (Strep. uberis, Strep. agalactiae and Strep. dysgalactiae) can be obtained by use of a combination of colony morphology, hemolysis type and catalase reaction, and a multiplex PCR with specific primers restricted to these 3 pathogens. The MALDI-TOF MS is a fast method that shows promising results, although identification of Strep. dysgalactiae at the subspecies level is not yet satisfactory.

Diagnostic gap in Bovine viral diarrhea virus serology during the periparturient period in cattle

Detection of antibodies against Bovine viral diarrhea virus (BVDV) in serum and milk by enzyme-linked immunosorbent assay (ELISA) is a crucial part of all ongoing national schemes to eradicate this important cattle pathogen. Serum and milk are regarded as equally suited for antibody measurement. However, when retesting a seropositive cow 1 day after calving, the serum was negative in 6 out of 9 different ELISAs. To further investigate this diagnostic gap around parturition, pre- and postcalving serum and milk samples of 5 cows were analyzed by BVDV antibody ELISA and serum neutralization test (SNT). By ELISA, 3 out of the 5 animals showed a diagnostic gap in the serum for up to 12 days around calving but all animals remained positive in SNT. In milk, the ELISA was strongly positive after birth but antibody levels decreased considerably within the next few days. Because of the immunoglobulin G (IgG)1-specific transport of serum antibodies into the mammary gland for colostrum production, the IgG subclass specificity of the total and the BVDV-specific antibodies were determined. Although all 5 animals showed a clear decrease in the total and BVDV-specific IgG1 antibody levels at parturition, the precalving IgG1-to-IgG2 ratios of the BVDV-specific antibodies were considerably lower in animals that showed the diagnostic gap. Results showed that BVDV seropositive cows may become "false" negative in several ELISAs in the periparturient period and suggest that the occurrence of this diagnostic gap is influenced by the BVDV-specific IgG subclass response of the individual animal.

Persistent infections after natural transmission of bovine viral diarrhoea virus from cattle to goats and among goats

Bovine viral diarrhoea virus (BVDV) is an economically important pathogen of cattle worldwide. Infection of a pregnant animal may lead to persistent infection of the foetus and birth of a persistently infected (PI) calf that sheds the virus throughout its life. However, BVD viruses are not strictly species specific. BVDV has been isolated from many domesticated and wild ruminants. This is of practical importance as virus reservoirs in non-bovine hosts may hamper BVDV control in cattle. A goat given as a social companion to a BVDV PI calf gave birth to a PI goat kid. In order to test if goat to goat infections were possible, seronegative pregnant goats were exposed to the PI goat. In parallel, seronegative pregnant goats were kept together with the PI calf. Only the goat to goat transmission resulted in the birth of a next generation of BVDV PI kids whereas all goats kept together with the PI calf aborted. To our knowledge, this is the first report which shows that a PI goat cannot only transmit BVD virus to other goats but that such transmission may indeed lead to the birth of a second generation of PI goats. Genetic analyses indicated that establishment in the new host species may be associated with step-wise adaptations in the viral genome. Thus, goats have the potential to be a reservoir for BVDV. However, the PI goats showed growth retardation and anaemia and their survival under natural conditions remains questionable.

Investigation of border disease and bovine virus diarrhoea in sheep from 76 mixed cattle and sheep farms in eastern Switzerland

The purpose of this study was to examine the occurrence of sheep persistently infected with Border disease virus (BDV) on 76 mixed cattle and sheep farms and whether seroconversion to BDV infection occurred in cattle of these farms. Seroprevalence of BDV and bovine viral disease virus (BVDV) infection in sheep was also investigated. Quantitative RT-PCR for pestivirus detection and an ELISA to detect pestivirus antibodies were used in 2'384 and 2'291 ovine blood samples, respectively. Another 27 seropositive sheep from ten flocks underwent serum neutralization testing to differentiate between BDV and BVDV antibodies. A BDV titre that was at least four times higher than the BVDV titre was interpreted as the result of BDV infection. Titres against BVDV were interpreted in an analogous fashion. All examined sheep were pestivirus-negative, 310 sheep were seropositive, 119 had an indeterminate titre and 1'862 were seronegative. The flock seroprevalence ranged from 0.0 to 73.9 %. Three of the 27 flocks that underwent serum neutralization testing were interpreted as BDV-infected because of 6 sheep with higher BDV titres, and 6 flocks were interpreted as BVDV-infected because of 14 sheep with higher BVDV titres.

Apoptosis in Bovine viral diarrhea virus (BVDV)-induced mucosal disease lesions: a histological, immunohistological, and virological investigation

Cattle persistently infected with a noncytopathic Bovine viral diarrhea virus (BVDV) are at risk of developing fatal "mucosal disease" (MD). The authors investigated the role of various apoptosis pathways in the pathogenesis of lesions in animals suffering from MD. Therefore, they compared the expression of caspase-3, caspase-8, caspase-9, and Bcl-2L1 (Bcl-x) in tissues of 6 BVDV-free control animals, 7 persistently infected (PI) animals that showed no signs of MD (non-MD PI animals), and 11 animals with MD and correlated the staining with the localization of mucosal lesions. Caspase-3 and -9 staining were markedly stronger in MD cases and were associated with mucosal lesions, even though non-MD PI animals and negative controls also expressed caspase-9. Conversely, caspase-8 was not elevated in any of the animals analyzed. Interestingly, Bcl-x also colocalized with mucosal lesions in the MD cases. However, Bcl-x was similarly expressed in tissues from all 3 groups, and thus, its role in apoptosis needs to be clarified. This study clearly illustrates ex vivo that the activation of the intrinsic, but not the extrinsic, apoptosis pathway is a key element in the pathogenesis of MD lesions observed in cattle persistently infected with BVDV. However, whether direct induction of apoptosis in infected cells or indirect effects induced by the virus are responsible for the lesions observed remains to be established.

Complete genome sequences of both biotypes of a virus pair of bovine viral diarrhea virus subgenotype 1k

We determined the complete genome sequences of both biotypes of a virus pair of bovine viral diarrhea virus (BVDV) subgenotype 1k. The viruses were isolated from a persistently infected calf suffering from mucosal disease. Compared to the noncytopathic biotype, the cytopathic biotype contains an insertion of 84 nucleotides and 22 nucleotide changes.

Bovine viral diarrhea (BVD): from biology to control

Bovine viral diarrhea virus (BVDV) is endemic worldwide. Together with classical swine fever and border disease viruses, it belongs to the genus Pestivirus of the family Flaviviridae. Most infections with BVDV take a transient, acute, course. Only rarely BVDV persists in its hosts. Due to the early time point of infection in utero, persistently infected (PI) animals are immunotolerant to the infecting non-cytopathic BVDV. In such animals the virus may mutate to a cytopathic biotype, causing lethal mucosal disease. In BVD-endemic regions, approximately 1% of the animals are PI. Removal of all PI animals leads to extinction of BVD. This approach to BVD eradication has been vindicated in Scandinavia. Following the same principles, regional and country-wide eradication programs are run in different parts of the world. These programs differ in the way PI animals are detected and in the role of vaccines. The Scandinavian two-step method of detecting PI animals is based on (i) the high level of seroprevalence in herds where PI animals are present and (ii) on testing all animals for virus in such herds. However, the high average herd seroprevalence in Switzerland made it impossible to define a reasonable threshold for virus testing. Therefore, all animals were directly tested for virus in the year 2008 and all newborn calves until the end of 2012, when the PI prevalence had dropped to 0.02%. Vaccination remains prohibited. Since 2013, surveillance for BVD is accomplished by serology. As a unique consequence of eradication, over 7500 viral strains are available to us for genetic studies.