Fecal shedding and tissue infections demonstrate transmission of Mycobacterium avium subsp. paratuberculosis in group-housed dairy calves

International audienceAbstractCurrent Johne’s disease control programs primarily focus on decreasing transmission of Mycobacterium avium subsp. paratuberculosis (MAP) from infectious adult cows to susceptible calves. However, potential transmission between calves is largely overlooked. The objective was to determine the extent of MAP infection in calves contact-exposed to infectious penmates. Thirty-two newborn Holstein–Friesian calves were grouped into 7 experimental groups of 4, consisting of 2 inoculated (IN) calves, and 2 contact-exposed (CE) calves, and 1 control pen with 4 non-exposed calves. Calves were group housed for 3 months, with fecal samples were collected 3 times per week, blood and environmental samples weekly, and tissue samples at the end of the trial. The IN calves exited the trial after 3 months of group housing, whereas CE calves were individually housed for an additional 3 months before euthanasia. Control calves were group-housed for the entire trial. All CE and IN calves had MAP-positive fecal samples during the period of group housing; however, fecal shedding had ceased at time of individual housing. All IN calves had MAP-positive tissue samples at necropsy, and 7 (50%) of the CE had positive tissue samples. None of the calves had a humoral immune response, whereas INF-γ responses were detected in all IN calves and 5 (36%) CE calves. In conclusion, new MAP infections occurred due to exposure of infectious penmates to contact calves. Therefore, calf-to-calf transmission is a potential route of uncontrolled transmission on cattle farms

Quantifying transmission of Mycobacterium avium subsp. paratuberculosis among group-housed dairy calves

International audienceAbstractJohne’s disease (JD) is a chronic enteritis caused by Mycobacterium avium subsp. paratuberculosis (MAP), with control primarily aimed at preventing new infections among calves. The aim of the current study was to quantify calf-to-calf transmission of MAP among penmates in an experimental trial. Newborn Holstein bull calves (n = 32) were allocated into pens of 4, with 2 inoculated (IN) calves and 2 calves that were contact exposed (CE). Calves were group-housed for 3 months, with frequent collection of fecal and blood samples and tissue collection after euthanasia. The basic reproduction ratio (R0) was estimated using a final size (FS) model with a susceptible-infected model, based on INF-γ ELISA and tissue culture followed by qPCR. In addition, the transmission rate parameter (β) for new shedding events was estimated using a general linearized method (GLM) model with a susceptible-infected-susceptible model based on culture, followed by qPCR, of fecal samples collected during group housing. The R0 was derived for IN and CE calves separately, due to a difference in susceptibility, as well as differences in duration of shedding events. Based on the FS model, interferon-γ results from blood samples resulted in a R0IG of 0.90 (0.24, 2.59) and tissue culture resulted in a R0T of 1.36 (0.45, 3.94). Based on the GLM model, the R0 for CE calves to begin shedding (R0CE) was 3.24 (1.14, 7.41). We concluded that transmission of MAP infection between penmates occurred and that transmission among calves may be an important cause of persistent MAP infection on dairy farms that is currently uncontrolled for in current JD control programs

Arabidopsis Roots and Shoots Show Distinct Temporal Adaptation Patterns toward Nitrogen Starvation

Nitrogen (N) is an essential macronutrient for plants. N levels in soil vary widely, and plants have developed strategies to cope with N deficiency. However, the regulation of these adaptive responses and the coordinating signals that underlie them are still poorly understood. The aim of this study was to characterize N starvation in adult Arabidopsis (Arabidopsis thaliana) plants in a spatiotemporal manner by an integrative, multilevel global approach analyzing growth, metabolites, enzyme activities, and transcript levels. We determined that the remobilization of N and carbon compounds to the growing roots occurred long before the internal N stores became depleted. A global metabolite analysis by gas chromatography-mass spectrometry revealed organ-specific differences in the metabolic adaptation to complete N starvation, for example, for several tricarboxylic acid cycle intermediates, but also for carbohydrates, secondary products, and phosphate. The activities of central N metabolism enzymes and the capacity for nitrate uptake adapted to N starvation by favoring N remobilization and by increasing the high-affinity nitrate uptake capacity after long-term starvation. Changes in the transcriptome confirmed earlier studies and added a new dimension by revealing specific spatiotemporal patterns and several unknown N starvation-regulated genes, including new predicted small RNA genes. No global correlation between metabolites, enzyme activities, and transcripts was evident. However, this multilevel spatiotemporal global study revealed numerous new patterns of adaptation mechanisms to N starvation. In the context of a sustainable agriculture, this work will give new insight for the production of crops with increased N use efficiency

Prevalence and lameness-associated risk factors in Alberta feedlot cattle

Lameness in cattle is a health and welfare concern; however, limited information is available on risk factors and the relationship between lameness and common diseases like bovine respiratory disease (BRD). Therefore, the objectives of this study were to: 1) identify prevalence of lameness in feedlot cattle and related risk factors of cattle diagnosed as lame; and 2) determine associations between BRD occurrence and lameness. Feedlot cattle health records were available from 28 feedlots for 10 yr. The data set consisted of 663,838 cattle records, with 13.9% (92,156) diagnosed with a disease, including 32.3%, 46.0%, and 22.0% with lameness, BRD, and other diagnoses, respectively. Lameness was classified into four categories: foot rot (FR), joint infections (JI), lame with no visible swelling (LNVS), and injuries (INJ), with a prevalence of 74.5%, 16.1%, 6.1%, and 3.1%, respectively. Lameness was compared across cattle types (arrival date and weight) as well as age classification (calf vs. yearling), gender (steer vs. heifer), and season of placement in the feedlot (spring, summer, fall, and winter). Within the disease-diagnosed population, lameness represented 28.5% of treated fall-placed calves, 38.5% of winter-placed calves, and 40.8% of treated yearlings. Foot rot was the most common diagnosis with 74.5% of all lameness diagnoses, with winter- and fall-placed calves more likely to be diagnosed with FR compared to yearlings (OR: 1.19, 95% CI: 1.10–1.30 and OR: 1.46, 95% CI: 1.38–1.55, respectively). Joint infections were the second most common diagnosis (16.1%). Compared to yearlings, fall-placed calves had a higher odds (OR: 3.64, 95% CI: 3.12–4.24) for JI. Injuries and LNVS were the least common but again fall-placed calves had higher odds of this diagnosis compared to yearlings (OR: 2.26, 95% CI: 1.70–2.99 and OR: 9.10, 95% CI: 6.26–13.2, respectively). Gender was significantly different for JI as steers were less likely affected compared to heifers (OR: 0.687, 95% CI: 0.545–0.867), and more likely affected by LNVS (OR: 2.46, 95% CI: 1.57–3.84). Of all lameness-associated deaths, JI accounted for almost 50%. Finally, cattle diagnosed with BRD were subsequently more likely to be diagnosed with INJ, JI, or LNVS (P < 0.001 for all comparisons). In conclusion, animal type and gender were associated with type of lameness diagnoses, allowing feedlots to allocate resources to groups at highest risk and focus on early intervention strategies.info:eu-repo/semantics/publishedVersio

Vaccination against Foot-and-mouth disease : do initial conditions affect its benefit?

When facing incursion of a major livestock infectious disease, the decision to implement a vaccination programme is made at the national level. To make this decision, governments must consider whether the benefits of vaccination are sufficient to outweigh potential additional costs, including further trade restrictions that may be imposed due to the implementation of vaccination. However, little consensus exists on the factors triggering its implementation on the field. This work explores the effect of several triggers in the implementation of a reactive vaccination-to-live policy when facing epidemics of foot-and-mouth disease. In particular, we tested whether changes in the location of the incursion and the delay of implementation would affect the epidemiological benefit of such a policy in the context of Scotland. To reach this goal, we used a spatial, premises-based model that has been extensively used to investigate the effectiveness of mitigation procedures in Great Britain. The results show that the decision to vaccinate, or not, is not straightforward and strongly depends on the underlying local structure of the population-at-risk. With regards to disease incursion preparedness, simply identifying areas of highest population density may not capture all complexities that may influence the spread of disease as well as the benefit of implementing vaccination. However, if a decision to vaccinate is made, we show that delaying its implementation in the field may markedly reduce its benefit. This work provides guidelines to support policy makers in their decision to implement, or not, a vaccination-to-live policy when facing epidemics of infectious livestock disease

Dichotomy in the NRT Gene Families of Dicots and Grass Species

A large proportion of the nitrate (NO3−) acquired by plants from soil is actively transported via members of the NRT families of NO3− transporters. In Arabidopsis, the NRT1 family has eight functionally characterised members and predominantly comprises low-affinity transporters; the NRT2 family contains seven members which appear to be high-affinity transporters; and there are two NRT3 (NAR2) family members which are known to participate in high-affinity transport. A modified reciprocal best hit (RBH) approach was used to identify putative orthologues of the Arabidopsis NRT genes in the four fully sequenced grass genomes (maize, rice, sorghum, Brachypodium). We also included the poplar genome in our analysis to establish whether differences between Arabidopsis and the grasses may be generally applicable to monocots and dicots. Our analysis reveals fundamental differences between Arabidopsis and the grass species in the gene number and family structure of all three families of NRT transporters. All grass species possessed additional NRT1.1 orthologues and appear to lack NRT1.6/NRT1.7 orthologues. There is significant separation in the NRT2 phylogenetic tree between NRT2 genes from dicots and grass species. This indicates that determination of function of NRT2 genes in grass species will not be possible in cereals based simply on sequence homology to functionally characterised Arabidopsis NRT2 genes and that proper functional analysis will be required. Arabidopsis has a unique NRT3.2 gene which may be a fusion of the NRT3.1 and NRT3.2 genes present in all other species examined here. This work provides a framework for future analysis of NO3− transporters and NO3− transport in grass crop species

The Arabidopsis Nitrate Transporter NRT2.4 Plays a Double Role in Roots and Shoots of Nitrogen-Starved Plants

Plants have evolved a variety of mechanisms to adapt to N starvation. NITRATE TRANSPORTER2.4 (NRT2.4) is one of seven NRT2 family genes in Arabidopsis thaliana, and NRT2.4 expression is induced under N starvation. Green fluorescent protein and β-glucuronidase reporter analyses revealed that NRT2.4 is a plasma membrane transporter expressed in the epidermis of lateral roots and in or close to the shoot phloem. The spatiotemporal expression pattern of NRT2.4 in roots is complementary with that of the major high-affinity nitrate transporter NTR2.1. Functional analysis in Xenopus laevis oocytes and in planta showed that NRT2.4 is a nitrate transporter functioning in the high-affinity range. In N-starved nrt2.4 mutants, nitrate uptake under low external supply and nitrate content in shoot phloem exudates was decreased. In the absence of NRT2.1 and NRT2.2, loss of function of NRT2.4 (triple mutants) has an impact on biomass production under low nitrate supply. Together, our results demonstrate that NRT2.4 is a nitrate transporter that has a role in both roots and shoots under N starvation

Release of soluble vascular endothelial growth factor receptor-1 (sFlt-1) during coronary artery bypass surgery

<p>Abstract</p> <p>Background</p> <p>This study was conducted to follow plasma concentrations of sFlt-1 and sKDR, two soluble forms of the vascular endothelial growth factor (VEGF) receptor in patients undergoing coronary artery bypass graft (CABG) surgery with extracorporeal circulation (ECC).</p> <p>Methods</p> <p>Plasma samples were obtained before, during and after surgery in 15 patients scheduled to undergo CABG. Levels of sFlt-1 and KDR levels were investigated using specific ELISA.</p> <p>Results</p> <p>A 75-fold increase of sFlt-1 was found during cardiac surgery, sFlt-1 levels returning to pre-operative values at the 6^thpost-operative hour. In contrast sKDR levels did not change during surgery. The ECC-derived sFlt-1 was functional as judge by its inhibitory effect on the VEGF mitogenic response in human umbilical vein endothelial cells (HUVECs). Kinetic experiments revealed sFlt-1 release immediately after the beginning of ECC suggesting a proteolysis of its membrane form (mFlt-1) rather than an elevated transcription/translation process. Flow cytometry analysis highlighted no effect of ECC on the shedding of mFlt-1 on platelets and leukocytes suggesting vascular endothelial cell as a putative cell source for the ECC-derived sFlt-1.</p> <p>Conclusion</p> <p>sFlt-1 is released during CABG with ECC. It might be suggested that sFlt-1 production, by neutralizing VEGF and/or by inactivating membrane-bound Flt-1 and KDR receptors, might play a role in the occurrence of post-CABG complication.</p

Knowledge gaps that hamper prevention and control of Mycobacterium avium subspecies paratuberculosis infection

In the last decades, many regional and country‐wide control programmes for Johne's disease (JD) were developed due to associated economic losses, or because of a possible association with Crohn's disease. These control programmes were often not successful, partly because management protocols were not followed, including the introduction of infected replacement cattle, because tests to identify infected animals were unreliable, and uptake by farmers was not high enough because of a perceived low return on investment. In the absence of a cure or effective commercial vaccines, control of JD is currently primarily based on herd management strategies to avoid infection of cattle and restrict within‐farm and farm‐to‐farm transmission. Although JD control programmes have been implemented in most developed countries, lessons learned from JD prevention and control programmes are underreported. Also, JD control programmes are typically evaluated in a limited number of herds and the duration of the study is less than 5 year, making it difficult to adequately assess the efficacy of control programmes. In this manuscript, we identify the most important gaps in knowledge hampering JD prevention and control programmes, including vaccination and diagnostics. Secondly, we discuss directions that research should take to address those knowledge gaps.http://wileyonlinelibrary.com/journal/tbed2019-05-01hj2018Veterinary Tropical Disease