Evolution of bovine respiratory syncytial virus

Until now, the analysis of the genetic diversity of bovine respiratory syncytial virus (BRSV) has been based on small numbers of field isolates. In this report, we determined the nucleotide and deduced amino acid sequences of regions of the nucleoprotein (N protein), fusion protein (F protein), and glycoprotein (G protein) of 54 European and North American isolates and compared them with the sequences of 33 isolates of BRSV obtained from the databases, together with those of 2 human respiratory syncytial viruses and 1 ovine respiratory syncytial virus. A clustering of BRSV sequences according to geographical origin was observed. We also set out to show that a continuous evolution of the sequences of the N, G, and F proteins of BRSV has been occurring in isolates since 1967 in countries where vaccination was widely used. The exertion of a strong positive selective pressure on the mucin-like region of the G protein and on particular sites of the N and F proteins is also demonstrated. Furthermore, mutations which are located in the conserved central hydrophobic part of the ectodomain of the G protein and which result in the loss of four Cys residues and in the suppression of two disulfide bridges and an alpha helix critical to the three-dimensional structure of the G protein have been detected in some recent French BRSV isolates. This conserved central region, which is immunodominant in BRSV G protein, thus has been modified in recent isolates. This work demonstrates that the evolution of BRSV should be taken into account in the rational development of future vaccines.

Persistent infection of B lymphocytes by bovine respiratory syncytial virus

Bovine respiratory syncytial virus (BRSV) is a major cause of respiratory disease in young cattle. Here we demonstrate BRSV persistence at low levels in tracheobronchial and mediastinal lymph nodes up to 71 days after the experimental infection of calves. Positive results were obtained on viral genomic RNA and messenger RNA coding for the nucleoprotein, glycoprotein (G), and fusion protein (F). G and F proteins were also detected in the pulmonary lymph nodes by immunohistochemistry. Double-staining experiments revealed that viral antigen was present in B-lymphocytes. Coculture experiments with the lymph node cells showed that the virus was still able to infect permissive target cells, even though no cytopathic effect was recorded. In vitro studies indicate that BRSV was still able to replicate in bovine B-lymphocyte cell lines 6 months after infection. These results may also be relevant to the understanding not only of the epidemiology and the peculiarities of the immune response of BRSV infections but also of human respiratory syncytial virus infections.

Avian influenza A(H10N7) virus involvement in mass mortality of harbour seals (Phoca vitulina) in Sweden, March through October 2014

We provide the first scientific report of influenza A virus involvement in a mass mortality event among harbour seals (Phoca vitulina) off the west coast of Sweden. Avian influenza A (H10N7) virus was detected in the lungs of two affected animals. This subtype has not been reported in seals to date, nor has influenza A-associated mortality been reported in seals in Europe. Circulation of avian influenza viruses in mammals may have implications for public health.

Tick-borne encephalitis

Tick-borne encephalitis (TBE), a zoonotic arbovirosis caused by tick-borne encephalitis virus (TBEV), is an increasing public health concern. Infections result in neurological symptoms in humans and the virus has rapidly expanded to new geographical areas. Three subtypes are currently present in different parts of Europe and Asia. The virus is transmitted by ticks, mainly Ixodes spp., between small mammals such as rodents, which serve as virus amplifying hosts. Humans are infected sporadically, either by a tick bite or by ingestion of infected milk or milk products. Other mammals (e.g. ruminants) can also be infected, but most of the time do not show clinical signs. In contrast to rodents, other wild and domestic mammals probably play only a very small direct role in maintaining TBEV in an area, but they might play an important role as hosts in sustaining a large tick population. Therefore, the virus prevalence and the occurrence of TBE can be influenced by several environmental, genetic and behavioural factors associated with the virus, the vectors or the hosts, and understanding these factors is essential for implementation of effective control measures. This article reviews virus characteristics and the epidemiological and clinical aspects of TBEV infections and examines pathogenesis, diagnostic approaches and control measures.

Dynamics of virus infections involved in the bovine respiratory disease complex in Swedish dairy herds

The dynamics of bovine respiratory syncytial virus (BRSV), bovine parainfluenza virus 3 (PIV-3), bovine corona virus (BCoV) and bovine viral diarrhoea virus (BVDV) infections were studied in 118 dairy herds in south western Sweden. By using serology on paired samples from three ∼7 vs. ∼15-month-old calves per herd, the propagation of infections was investigated over about a 1-year period. The results implied that at least 74% of calves had experienced one or more of the monitored infections at the age of ∼7 months (Sample 1, Spring); 30%, 48%, 34% and 8% were seropositive to BRSV, PIV-3, BCoV and BVDV, respectively. Seroconversions to BRSV, PIV-3, BCoV and BVDV occurred in 26%, 38%, 50% and 3% of seronegative animals and 63% had antibodies against two or more infections at ∼15 months (Sample 2). In total, 90–97% of animals that were seropositive in Sample 1 remained positive in Sample 2. A significant association was found between BVDV and BCoV (P = 0.01). Moreover, a significantly higher proportion of herds in which no calves had a recorded history of respiratory disease (n = 15) were classified as negative to all four infections monitored when compared to herds in which disease was observed (P = 0.0002). This study showed a high infection burden in young animals and effective spread of BRSV, PIV-3 and BCoV in one area of Sweden. BVDV infections were restricted to a few herds, reflecting the effect of a voluntary control program against BVDV in Sweden.

Peripheral immune responses in pregnant cattle following Neospora caninum infection

Experimental infection of cattle with Neospora caninum in early gestation causes foetal death, but the foetus survives infection in late gestation. An immunological mechanism of abortion has been suggested; therefore changes in the maternal immune response during pregnancy could account for these differences. We have investigated the peripheral immune responses of pregnant cattle following an intravenous inoculation with 10(7) N. caninum tachyzoites in early and late gestation. Percentages of CD2+ and CD4+ T-cells in peripheral blood mononuclear cells (PBMC) increased 1-2 weeks after infection in both early (day 70) and late (day 210) gestation, and percentages of CD8+ T-cells increased 1-2 weeks after infection at day 70. Interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) mRNA expression in PBMC increased 1-2 weeks after infection at day 210 and IL-4 increased 1-2 weeks after infection at day 70. Immunomagnetic isolation of CD4+ cells from PBMC showed that they were a major source of IL-4 and IFN-gamma, and expression of both cytokines increased in CD4+ cells after infection in early and late gestation. These results suggest that CD4+ cells proliferate and express IL-4 and IFN-gamma in response to N. caninum irrespective of the stage of gestation when infection occurs.

Evaluation of a nested reverse transcription-PCR assay based on the nucleoprotein gene for diagnosis of spontaneous and experimental bovine respiratory syncytial virus infections

The first nested reverse transcription (RT)-PCR based on the nucleoprotein gene (n RT-PCR-N) of the bovine respiratory syncytial virus (BRSV) has been developed and optimized for the detection of BRSV in bronchoalveolar lavage fluid cells of calves. This test is characterized by a low threshold of detection (0.17 PFU/ml), which is 506 times lower than that obtained by an enzyme immunosorbent assay (EIA) test (RSV TESTPACK ABBOTT). During an experimental infection of 17 immunocompetent calves less than 3 months old, BRSV RNA could be detected up to 13 days after the onset of symptoms whereas isolation in cell culture was possible only up to 5 days. Compiling results obtained by conventional techniques (serology, antigen detection, and culture isolation) for 132 field samples collected from calves with acute respiratory signs revealed that n RT-PCR-N showed the highest diagnostic sensitivity and very good specificity. This n RT-PCR-N with its long period of detection during BRSV infection thus provides a valuable tool for diagnostic and epidemiological purposes.

Limited interlaboratory comparison of Schmallenberg virus antibody detection in serum samples

Eight veterinary institutes in seven different countries in Europe participated in a limited interlaboratory comparison trial to evaluate laboratory performances of Schmallenberg virus (SBV) antibody detection in serum. Seven different sheep sera and three different cattle sera were circulated, and all participating institutes were asked to test these sera using SBV antibody detection assay(s) in place in their laboratories. All laboratories within the trial performed a virus neutralisation test (VNT) as well as one or two ELISAs on all samples, and swiftly detected SBV antibodies using these assays. VNT was more sensitive in detecting SBV antibodies than several of the used ELISA assays. Based on the test results, one cattle and one sheep SBV antibody-positive serum were selected to serve as reference sera, which now can be supplied to other laboratories on request.

Schmallenberg Virus beyond Latitude 65°N

Extensive and rapid spread of Schmallenberg virus (SBV) in Sweden was detected by consecutive serological bulk milk surveys conducted before and after the vector season of 2012. Whereas <0.2% of cattle herds tested positive in a first survey in spring 2012, SBV-specific antibodies were detected in almost 75% of 723 bulk milk samples randomly collected all over the country 6 months later, beyond the 65th northern latitude, and with an observed spatial distribution suggesting multiple introductions of the virus. Circulation of virus was later confirmed by the detection of SBV in malformed lambs and calves starting from November 2012 and January 2013, respectively. These observations suggest SBV circulation starting from July 2012, with a peak in transmission between August and October. A local heterogeneity of within-herd seroprevalence was found, indicating that SBV-naïve animals remain also in highly infected areas enabling the re-emergence of the infection in the coming vector season.

Comparative study of the action of flunixin meglumine and tolfenamic acid on prostaglandin E2 synthesis in bovine inflammatory exudate

An acute non-immune inflammation model was used to compare the action of two non-steroidal anti-inflammatory drugs, flunixin meglumine and tolfenamic acid, on prostaglandin E2 (PGE2) synthesis in bovine inflammatory exudate. The tissue cage model used involves subcutaneous implantation of polypropylene cages and subsequent stimulation by carrageenan injection of the granulation tissue which develops within the cage. Twelve calves were randomly assigned to three groups receiving placebo, flunixin meglumine and tolfenamic acid, respectively. Inflammatory exudate was sampled 30 min after carrageenan injection and at seven subsequent time points. PGE2 levels were determined by radioimmunoassay. At each time point post-carrageenan injection, flunixin meglumine inhibited PGE2 synthesis to a greater extent than tolfenamic acid. At 4, 8, 12 and 24 h these differences were statistically significant.

Flow cytometric analysis of bovine CD4 and CD8 lymphocytes: influence of blood sampling and processing methods

Technical information to facilitate bovine blood treatment for optimum lymphocyte flow cytometry analysis is reported. Murine monoclonal antibodies CC8 and CC63 were used to identify phenotypes corresponding to bovine CD4 T cells and CD8 T cells. Blood samples collected in acid citrate dextrose (ACD) enhanced leucocyte subpopulation separation compared with ethylenediamine tetra-acetic acid, heparin and sodium citrate. To preserve bovine blood before immunophenotyping, samples collected in ACD may be kept at 22 degrees C or at 4 degrees C and should be analysed within 32 hours. For isolation of white blood cells, whole blood lysis was faster and gave the same results as Ficoll gradient separation 1.077 and Ficoll gradient separation 1.083. After immunophenotyping, blood could be stored at 4 degrees C if fixed with paraformaldehyde within seven days. Owing to diurnal variations, blood should be collected at a standard time of the day.

159 CHANGES IN PROTEIN EXPRESSION PROFILES IN BOVINE ENDOMETRIAL EPITHELIAL CELLS (bEEC) FOLLOWING E. COLI LIPOPOLYSACCHARIDE CHALLENGE

E. coli is one of the most frequent bacteria involved in uterine diseases. Lipopolysaccharide (LPS) is a component of the outer membrane of Gram-negative bacteria involved in the pathogenic processes leading to postpartum metritis and endometritis in cattle. It also causes inflammation of the endometrium. Increase of cell proliferation by LPS is part of the inflammatory process and has been reported in human epithelial and immune cells (Martin et al. 2000 J. Immunol. 165, 139–147) and from bovine endometrial epithelial cells (bEEC) (Guo et al. 2014 Reprod. Fertil. Dev. 26, 165–166). The aim of this study was to investigate possible changes in protein expression in relation with the proliferative response of bEEC after challenge with E. coli-LPS. In vitro culture of bEEC was performed from 3 cows. On passage 5, bEEC from each individual were exposed to 0, 8, and 16 µg mL–1 LPS for 72 h. At time 0 and 72 h later, attached cells were counted and for each time and LPS dosage, cells were frozen for proteomic analyses. The variation of cells number over time was analysed by ANOVA (SAS 9.1, proc GLM; SAS Institute, Inc., Cary, NC, USA). All samples were analysed (every sample run in triplicate) by 2-D gel electrophoresis coupled to matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF)/time-of-flight (TOF) mass spectrometry (MS) and shotgun nLC-MS/MS analysis. As reported before, a significant increase in cell number was observed for cells treated with 8 µg mL–1 LPS (P ≤ 0.001), whereas changes in cell number were highly variable and nonsignificant for 16 µg mL–1 LPS. From each sample, ~800 proteins were visualised. Results from 2-D gel coupled to MALDI-TOF/TOF were very reproducible (same responses between individual cows) and revealed changes in protein profiles very much related (from P < 0.05 to P < 0.01) to proliferative phenotypes for seven proteins. From shotgun analysis, 27 proteins were found significantly differentially expressed (P < 0.05 to P < 0.01) following exposure to LPS (21 up-regulated and 6 down-regulated). Among the 21 found as up-regulated, 20 were differentially expressed both for the 8 and 16 µg mL–1 LPS, whereas 5 out of 6 were down-regulated for both dosages. Differentially expressed proteins were associated to cell proliferation, apoptosis, oxidative stress, regulation of histones, allergy, and general cell metabolism pathways. Candidate proteins need to be confirmed from larger series of individuals and relevant pathways further studied. Research was partially funded by RMUSTV.

Abnormal ruminal digestion in cattle with dominantly non-digestive disorders

Health disturbances of ruminal origin in cattle are summed up. The problems are classified in those caused by special feed (NPN for example), those caused by insufficient ruminal detoxication capacity (poisoning by nitrate or aliphatic N-derivates) and belonging to ruminal toxin production (3-methyl-indole, S-methyl-cysteine-sulfoxide, glucosinolates) and arranged in pathophysiological sense.

158 BOVINE HERPES VIRUS 4 (BoHV4) INHIBITS BOVINE ENDOMETRIAL EPITHELIAL CELL (bEEC) PROLIFERATION

BoHV4 is a double-stranded DNA virus which has been associated to endometritis, metritis, and abortions in dairy cow. The objective of this study was to characterise its cytopathic effects on bovine endometrial epithelial cells (bEEC). Bovine uteri were collected from slaughter house and bEEC separated and cultivated as previously described (Guo et al. 2014 Reprod. Fertil. Dev. 26, 165–166). In Experiment 1 (Exp 1), bEEC (passage 5) from 3 cows were cultivated for 6 days without virus or following exposure to serial dilutions (10–4, 10–3, 10–2) of virus. Living cells were counted for each group at start of the experiment and by Day 6. Proliferation or inhibition of proliferation was calculated by (Number of cells Day 6 – Number of cells Day 0)/Number of cells Day 0. In Experiment 2 (Exp 2) cells were challenged with a single dosage of virus (MOI 0.01; 1 virus: 100 cells) and culture performed during 1, 2, 3, 4, 5, 6, or 7 days. Cells were counted at Day 0 and each day, proliferation of cells was calculated as (number of cells by Day X – number of cells Day 0)/number of cells Day 0. The effects of the dilution of virus, cow and their interaction (Exp 1) or effects of time, cow, viral exposure, and second-order interactions (Exp 2) on cow cell proliferation were analysed by ANOVA (SAS 9.2, proc GLM; SAS Institute, Inc., Cary, NC, USA). In Exp 1, the amount of living cells by Day 6 was very significantly increased in controls when compared to Day 0 (+172.6 ± 24%; P < 0.0001). A linear inhibition of proliferation was observed with increasing dilutions of virus. The number of living cells for the highest concentration of virus is not different from Day 0 numbers (–26.7 ± 24.6%). Pattern of proliferation differed between cows as evidenced by a significant interaction between cow and virus dilution (P < 0.001). In Exp 2, we observed a very strong increase of proliferation from Day 0 to Day 7 in controls (+1000 ± 87%; P < 0.0001). From Day 1 to 4, the increase in number of cells was very similar for cells exposed to BoHV4 and in controls. However, after Day 4, cells exposed to virus had a limited proliferation or expressed cell death as the number of living cells by Day 7 were not different from these observed by Day 0 (50 ± 87%; NS). These results show that both time and dose of BoHV4 affect the proliferation of bovine EEC. These results will be used to investigate further the molecular mechanisms by which BoHV4 induces cell death and their sequence. Research was partly funded by RMUTSV.

124 CHANGES IN GENE EXPRESSION FOLLOWING EXPOSURE OF BOVINE ENDOMETRIAL EPITHELIAL CELLS (bEEC) TO ESCHERICHIA COLI LPS; THEIR POSSIBLE EFFECT ON IMPLANTATION

Lipopolysaccharide (LPS) is a component of the outer membrane of gram-negative bacteria and is involved in postpartum uterine infection in cattle. Lipopolysaccharide causes inflammation of the endometrium and the activation of immune and pro-inflammatory pathways in uterine cells has been well documented. This study was performed to investigate the effects of LPS on epithelial cells from whole-genome information, and this abstract focuses on genes and pathways involved in the regulation of implantation. Following in vitro culture of bovine endometrial epithelial cells (bEEC), passage 4 epithelial cell samples from 3 cows were exposed to 0, 2, and 8 µg mL−1 LPS (Sigma L2630, Escherichia coli O111:B4, Sigma Chemical Co., St. Louis, MO, USA) for 24 h. At time 0 and at 24 h for each LPS dosage, RNA was extracted by using the All prep DNA/RNA Universal kit (Qiagen, Valencia, CA, USA). Samples were analysed by RNA sequencing performed in the SciLife Laboratory in Uppsala. Differentially expressed genes (DEG) were identified by using Ensemble genes as a reference. No DEG were found between 2 and 8 µg mL−1 LPS-treated samples and at 24 h 2035 DEG were identified (Benjamini-Hochberg adjusted P-value < 0.05) between controls and samples treated with 2 µg mL−1 LPS. Gene ontology analysis did show that DEG were associated to immune response (up), response to stress and external stimuli (up), catalytic activity (up), cell cycle, anatomical structures especially cell membrane, and adhesion (down) pathways. In the latest, numerous specific genes in relation with implantation were highly deregulated. This includes down-regulation of 8 members of the cadherin superfamily. On the contrary, 4 members of the mucin family were strongly up-regulated by LPS (MUC1, MUC13, MUC16, F1MUC1). Molecules such as plakophilins and desmogleins involved in desmosomes, in tight junctions, and in the control of cell adhesion were also deregulated. Specific changes occurred in immune response related with implantation [strong up-regulation of the immunoglobulin superfamily members such ICAM1 (or CD54) and down-regulation of ALCAM]. A set of 10 molecules belonging to the family of integrins and their binding partners were also deregulated [for instance, down-regulation of osteopontin (SPP1)]. In addition, LPS deregulated a large set of genes binding the above molecules (such as galectins LGALS1, S3, S9) and more than 20 transcripts coding for cytokines and their receptors. A large series of interferon-induced genes (IFITS) and genes coding for interferon-induced trans membrane proteins (IFITM) were highly up-regulated by LPS. This may be of functional importance due to the fact that all those genes are normally up-regulated by interferon tau from embryonic origin. The above results show that the function of endometrial epithelial cells is profoundly affected by LPS and that most of the key signals involved in implantation are deregulated. It is likely that these LPS-induced changes strongly perturb lately endometrial responsiveness to embryos at the time of implantation. Research was done with the financial support of FP7 project “Prolific” and RMUTSV (Thailand).

Selection of foot and mouth disease vaccine strains--a review

The choice of the most appropriate strains of foot and mouth disease (FMD) virus vaccines to use in FMD control programmes and to store in vaccine antigen reserves is based on the matching of representative field isolates from outbreaks around the world to available vaccine strains. However, those involved in FMD control at a national level do not always give this work a high priority, while in countries without effective control of FMD there is little incentive to collect samples or to overcome the constraints on submission to international reference laboratories. In the short term, specific initiatives for targeted collection can provide samples on a periodic basis, but a long-term solution requires the development of FMD control measures. This must be underpinned by the strengthening of local Veterinary Services and laboratories, and by demand-driven provision of sufficient amounts of high-quality vaccine. Difficulties may be increased by commercial constraints on disclosure of the strains used for vaccine production and on the supply of reagents needed for matching tests. Vaccine matching tests are mainly based on in vitro methods - such as virus neutralisation, enzyme-linked immunosorbent assay with polyclonal antibodies and complement fixation - and are performed in a relatively small number of laboratories around the world. In addition to the difficulties of gathering representative field and vaccine strains, neither the reagents nor the methods used for vaccine matching are fully harmonised. Consequently, there is no strict equivalence in the results obtained. Alternative approaches using monoclonal antibody panels and/or viral capsid gene sequencing are being developed and could complement the currently employed serological tests. However, there is limited in vivo cross-protection information, more of which is essential for future validation of the vaccine matching methods. In response to the funding and leadership deficit for vaccine strain selection, a network of World Organisation for Animal Health (OIE) and Food and Agriculture Organization FMD reference laboratories has been established; this gives these laboratories the potential to strengthen the coordination of their work and reporting and thereby improve recommendations on vaccine strain selection.

[Retrospective study of foot and mouth disease in West Africa from 1970 to 2003]

A retrospective study of foot and mouth disease in seven West African countries was conducted for the period 1970 to 2003. The study included three cattle-exporting Sahel countries (Burkina-Faso, Mali and Niger) and four cattle-importing coastal countries (Benin, Côte d'lvoire, Ghana and Togo). Foot and mouth disease has been enzootic in these countries since 1990/1991. Four of the seven serotypes are regularly notified (O, A, SAT 1 and SAT 2). In the seven countries as a whole, 198 biological samples from identified foot and mouth disease outbreaks confirmed the involvement of the following serotypes: O (62 outbreaks); A (32 outbreaks); SAT 1 (18 outbreaks); SAT 2 (86 outbreaks). This result, which is largely underestimated, clearly demonstrates the seriousness of foot and mouth disease in West Africa, whose livestock production system characterised by continual uncontrolled animal movements facilitates the spread of the disease. Unlike in Southern Africa, for foot and mouth disease to be controlled in West Africa it is necessary immediately to introduce a regional strategy involving all countries which takes into account the real situation in the field: transhumance, nomadism and live-animal imports by coastal countries.