Ganjam virus/Nairobi sheep disease virus induces a pro-inflammatory response in infected sheep

Partly due to climate change, and partly due to changes of human habitat occupation, the impact of tick-borne viruses is increasing. Nairobi sheep disease virus (NSDV) and Ganjam virus (GV) are two names for the same virus, which causes disease in sheep and goats and is currently known to be circulating in India and East Africa. The virus is transmitted by ixodid ticks and causes a severe hemorrhagic disease. We have developed a real-time PCR assay for the virus genome and validated it in a pilot study of the pathogenicity induced by two different isolates of NSDV/GV. One isolate was highly adapted to tissue culture, grew in most cell lines tested, and was essentially apathogenic in sheep. The second isolate appeared to be poorly adapted to cell culture and retained pathogenicity in sheep. The real-time PCR assay for virus easily detected 4 copies or less of the viral genome, and allowed a quantitative measure of the virus in whole blood. Measurement of the changes in cytokine mRNAs showed similar changes to those observed in humans infected by the closely related virus Crimean Congo hemorrhagic fever virus.     

Healthy goats naturally devoid of prion protein

Prion diseases such as scrapie in small ruminants, bovine spongiform encephalopathy (BSE) in cattle and Creutzfeldt-Jakob disease (CJD) in man, are fatal neurodegenerative disorders. These diseases result from the accumulation of misfolded conformers of the host-encoded prion protein (PrP) in the central nervous system. To date naturally-occurring PrP free animals have not been reported. Here we describe healthy non-transgenic animals, Norwegian Dairy Goats, lacking prion protein due to a nonsense mutation early in the gene. These animals are predicted to be resistant to prion disease and will be valuable for research and for production of prion-free products.     

Trichomonas gallinae, in comparison to Tetratrichomonas gallinarum, induces distinctive cytopathogenic effects in tissue cultures

In the present study the interaction of three genetically different clonal cultures of Trichomonas gallinae and Tetratrichomonas gallinarum with a permanent chicken liver (LMH) and a permanent quail fibroblast (QT35) cell culture was studied. Proliferation of T. gallinae cells was associated with a disintegration of the cell monolayer. The initial lesions on the LMH monolayer consisted of a progressive accumulation of the flagellate, forming clumps attached to the monolayer. A prolonged incubation time was characterized by appearance of holes in the cell monolayer with accumulation of trichomonads at their periphery. According to the severeness of the monolayer disruption differences among three tested T. gallinae clones were noticed. Furthermore, filtrates obtained either from axenic cultures of T. gallinae or from infected cell cultures produced a cytopathogenic effect similar to the protozoal cells, on both types of cell cultures. However, the destructive effect of the flagellates and their cell-free filtrates was much more pronounced on the LMH monolayer in comparison with the QT35 cells. Furthermore, freshly seeded LMH and QT35 cells suspended in cell-free filtrates of T. gallinae were unable to form a confluent monolayer. In comparison to T. gallinae, clonal cultures of T. gallinarum or their cell-free filtrates produced no effect on both types of monolayers. Interestingly, the cell-free filtrates obtained from both trichomonad species had an effect on the viability of both cell cultures. However, the cytotoxic effect of T. gallinarum filtrates was less severe than that recorded by T. gallinae. Consequently, for the first time a destruction of specified monolayers induced by T. gallinae-free filtrates could be demonstrated.     

Evaluation of shock waveform configuration on the defibrillation capacity of implantable cardioverter defibrillators in dogs

BackgroundImplantable cardioverter defibrillators (ICD) are programmed to detect ventricular arrhythmias and terminate them by delivering an electrical shock. A defibrillation threshold (DFT) at least 10 J below the maximum device output is recommended for successful therapy. Shock waveform configuration is a programmable parameter used to achieve a low DFT. It is hypothesized that a fixed-pulse configuration results in lower defibrillation energy requirements than a fixed-tilt configuration.Animals10 mongrel dogs.Materials and methodsICD generator and transvenous lead were surgically implanted. Defibrillation threshold was determined using a protocol guided by the upper limit of vulnerability. Fixed-pulse and fixed-tilt (50%/50%) waveform configurations were tested in a random order. Plasma cardiac troponin I (cTnI) was measured for signs of myocardial injury.ResultsThe experiment was completed in 9 dogs. Overall mean DFT value was 424 ± 88 V (9.2 ± 3.9 J). Mean differences among voltage, energy and impedance at the DFT for fixed-pulse (422 ± 97 V, 9.1 ± 4.2 J, 62.6 ± 13.8 Ω) and fixed-tilt (426 ± 83 V, 9.3 ± 3.8 J, 62.8 ± 18.5 Ω) configurations were not statistically significant (All P > 0.21). Cardiac TnI concentration changed from 0.03 ng/mL (95% CI: 0.02–0.04) at baseline to 0.11 ng/mL (95 CI: 0.08–0.16) after DFT was obtained with the first waveform configuration and 0.19 ng/mL (95% CI: 0.13–0.28) at the end of the study period. There were no significant changes in heart rate, end-tidal CO2 and blood pressure over time (all P > 0.09).ConclusionThe tested ICD device and lead placement reliably produced acceptable DFT values, based on a 10-J safety margin below the maximum device output. A benefit of fixed-pulse configuration could not be demonstrated over the standard fixed-tilt waveform. Signs of acute myocardial damage from repeated high-voltage shocks and episodes of ventricular fibrillation seemed of limited clinical significance.     

Uterine biology in pigs and sheep

There is a dialogue between the developing conceptus (embryo-fetus and associated placental membranes) and maternal uterus which must be established during the peri-implantation period for pregnancy recognition signaling, implantation, regulation of gene expression by uterine epithelial and stromal cells, placentation and exchange of nutrients and gases. The uterus provide a microenvironment in which molecules secreted by uterine epithelia or transported into the uterine lumen represent histotroph required for growth and development of the conceptus and receptivity of the uterus to implantation. Pregnancy recognition signaling mechanisms sustain the functional lifespan of the corpora lutea (CL) which produce progesterone, the hormone of pregnancy essential for uterine functions that support implantation and placentation required for a successful outcome of pregnancy. It is within the peri-implantation period that most embryonic deaths occur due to deficiencies attributed to uterine functions or failure of the conceptus to develop appropriately, signal pregnancy recognition and/or undergo implantation and placentation. With proper placentation, the fetal fluids and fetal membranes each have unique functions to ensure hematotrophic and histotrophic nutrition in support of growth and development of the fetus. The endocrine status of the pregnant female and her nutritional status are critical for successful establishment and maintenance of pregnancy. This review addresses the complexity of key mechanisms that are characteristic of successful reproduction in sheep and pigs and gaps in knowledge that must be the subject of research in order to enhance fertility and reproductive health of livestock species.     

Risk factors for death from canine parvoviral-related disease in Australia

Canine parvovirus (CPV) is a highly contagious cause of serious and often fatal disease in dogs worldwide despite the availability of safe and efficacious vaccines. Although a number of studies have focussed on identifying risk factors in disease development, risk factors associated with death from CPV are largely unknown. In this study we analysed a total of 1451 CPV cases reported from an Australian surveillance system - using univariate and multivariate techniques - to determine significant risk factors associated with death and euthanasia. A crude case fatality rate of 42.3% was estimated - higher than has been reported previously. We found that 3.3% of CPV cases had a history of vaccination in the previous 12 months, despite having completed the primary puppy vaccination course. The majority (89.5%) of these cases occurred in dogs <12 months of age, indicating failure of the primary vaccination course to provide protective immunity (most likely due to interference of the vaccine antigen with maternal antibodies but other reasons are discussed). Extending the age at which the final puppy vaccination is administered might be one of several strategies to consider. The final multivariate model showed that in non-litter CPV cases, risk of death was significantly associated with season of diagnosis (summer) and pedigree type (hounds and non-sporting dogs). Euthanasia in non-litter CPV cases was significantly associated with season of diagnosis (summer), state of residence (Northern Territory/South Australia/Tasmania combined), age (相似文献   

Invasion of canine erythrocytes by Bartonella vinsonii subsp. berkhoffii

Bartonella vinsonii subsp. berkhoffii is a recognized cause of endocarditis in dogs and human patients and has been associated with cardiac arrhythmias, myocarditis, granulomatous lymphadenitis, polyarthritis, and granulomatous rhinitis in dogs. Little is known regarding the mode of transmission or cellular localization of this bacteria following infection of a canine host. The aim of the current study was to determine whether erythrocytes may serve as a site of infection by B. vinsonii subsp. berkhoffii. In the study, we successfully demonstrate the invasion of canine erythrocytes by a B. vinsonii subsp. berkhoffii genotype III strain using an in vitro model system. Dog erythrocytes were incubated with B. vinsonii subsp. berkhoffii after which tubes were treated with gentamicin at 12, 24, and 48 h post-inoculation. After gentamicin elimination of extracellular bacteria, there was a gradual increase in intra-erythrocytic bacteria, as assessed by colony forming units per ml, at each collection time point. The largest recovery of intracellular bacteria occurred at 48 h post-infection. These results suggest that canine erythrocytes may serve in the maintenance of bacteremia due to B. vinsonii subsp. berkhoffii within an infected host.     

Interactive effects of nocturnal transpiration and climate change on the root hydraulic redistribution and carbon and water budgets of southern United States pine plantations

Deep root water uptake and hydraulic redistribution (HR) have been shown to play a major role in forest ecosystems during drought, but little is known about the impact of climate change, fertilization and soil characteristics on HR and its consequences on water and carbon fluxes. Using data from three mid-rotation loblolly pine plantations, and simulations with the process-based model MuSICA, this study indicated that HR can mitigate the effects of soil drying and had important implications for carbon uptake potential and net ecosystem exchange (NEE), especially when N fertilization is considered. At the coastal site (C), characterized by deep organic soil, HR increased dry season tree transpiration (T) by up to 40%, and such an increase affected NEE through major changes in gross primary productivity (GPP). Deep-rooted trees did not necessarily translate into a large volume of HR unless soil texture allowed large water potential gradients to occur, as was the case at the sandy site (S). At the Piedmont site (P) characterized by a shallow clay-loam soil, HR was low but not negligible, representing up to 10% of T. In the absence of HR, it was predicted that at the C, S and P sites, annual GPP would have been diminished by 19, 7 and 9%, respectively. Under future climate conditions HR was predicted to be reduced by up to 25% at the C site, reducing the resilience of trees to precipitation deficits. The effect of HR on T and GPP was predicted to diminish under future conditions by 12 and 6% at the C and P sites, respectively. Under future conditions, T was predicted to stay the same at the P site, but to be marginally reduced at the C site and slightly increased at the S site. Future conditions and N fertilization would decrease T by 25% at the C site, by 15% at the P site and by 8% at the S site. At the C and S sites, GPP was estimated to increase by 18% and by >70% under future conditions, respectively, with little effect of N fertilization. At the P site, future conditions would stimulate GPP by only 12%, but future conditions plus N fertilization would increase GPP by 24%. As a consequence, in all sites, water use efficiency was predicted to improve dramatically with future conditions. Modeling the effect of reduced annual precipitation indicated that limited water availability would decrease all carbon fluxes, including NEE and respiration. Our simulations highlight the interactive effects of nutrients and elevated CO(2), and showed that the effect of N fertilization would be greater under future climate conditions.     

Edge type affects leaf-level water relations and estimated transpiration of Eucalyptus arenacea

While edge effects on tree water relations are well described for closed forests, they remain under-examined in more open forest types. Similarly, there has been minimal evaluation of the effects of contrasting land uses on the water relations of open forest types in highly fragmented landscapes. We examined edge effects on the water relations and gas exchange of a dominant tree (Eucalyptus arenacea Marginson & Ladiges) in an open forest type (temperate woodland) of south-eastern Australia. Edge effects in replicate woodlands adjoined by cleared agricultural land (pasture edges) were compared with those adjoined by 7- to 9-year-old eucalypt plantation with a 25m fire break (plantation edges). Consistent with studies in closed forest types, edge effects were pronounced at pasture edges where photosynthesis, transpiration and stomatal conductance were greater for edge trees than interior trees (75m into woodlands), and were related to greater light availability and significantly higher branch water potentials at woodland edges than interiors. Nonetheless, gas exchange values were only ～50% greater for edge than interior trees, compared with ～200% previously found in closed forest types. In contrast to woodlands adjoined by pasture, gas exchange in winter was significantly lower for edge than interior trees in woodlands adjoined by plantations, consistent with shading and buffering effects of plantations on edge microclimate. Plantation edge effects were less pronounced in summer, although higher water use efficiency of edge than interior woodland trees indicated possible competition for water between plantation trees and woodland edge trees in the drier months (an effect that might have been more pronounced were there no firebreak between the two land uses). Scaling up of leaf-level water relations to stand transpiration using a Jarvis-type phenomenological model indicated similar differences between edge types. That is, transpiration was greater at pasture than plantation edges in summer months (most likely due to greater water availability at pasture edges), resulting in significantly greater estimates of annual transpiration at pasture than plantation edges (430 vs. 343lm(-2)year(-1), respectively). Our study highlights the need for landscape-level water flux models to account for edge effects on stand transpiration, particularly in highly fragmented landscapes.     

Host and environmental reservoirs of infection for bovine digital dermatitis treponemes

Bovine digital dermatitis (BDD) is a global infectious disease causing lameness of cattle and is responsible for substantial animal welfare issues and economic losses. The causative agents are considered to be spirochetal bacteria belonging to the genus Treponema, which have consistently been identified in BDD lesions worldwide. One potential means of controlling infection is the disruption of transmission; however, the infection reservoirs and transmission routes of BDD treponemes have yet to be elucidated. To address these issues, we surveyed for evidence of BDD treponeme presence in the dairy farm environment, in bovine tissues and in bovine gastrointestinal (GI) tract contents. A total of 368 samples were tested using PCR assays specific for each of three currently recognised, isolated phylotypes of BDD treponemes. All environmental samples, together with insects and GI tract content samples were negative for BDD treponeme DNA from the three phylotypes. However, we identified BDD treponemes in two non-pedal bovine regions: the oral cavity (14.3% of cattle tested) and the rectum (14.8% of cattle tested). Whilst only single phylotypes were detected in the oral cavity, two of the rectal tissues yielded DNA from more than one phylotype, with one sample yielding all three BDD treponeme phylotypes. Whilst it might be considered that direct skin to skin contact may be a major transmission route of BDD treponemes, further studies are required to characterise and determine the potential contribution of oral and rectal carriage to BDD transmission.