Survival of Johne’s Disease in the environment : National Ovine Johne's Disease Control and Evaluation Program.

This report covers three MLA projects (TR.055, TR.055A and OJD.003) undertaken by NSW Agriculture to determine how long the sheep strain of Mycobacterium paratuberculosis survives in the environment to validate destocking recommendations for eradication of OJD. Survival of the organism was prolonged but finite. In the shade it lasted for 13 months while in the open in ungrazed pasture it lasted for 7 months. It survived for a shorter period in fully exposed pastures where grazing was simulated but for much longer in water than on pasture. These times were probably underestimates. Liming pasture did not reduce survival and moisture did not increase it. Shade was the most significant factor favouring survival. Further research is necessary to determine the mechanisms of survival, which include dormancy. Decay rates for the organism were determined for short term and long term destocking. These can be used to estimate how much time must be allowed to render pastures safe for control and eradication of OJD, respectively. When estimates of soil ingestion rates by grazing sheep are combined with within-flock OJD prevalence estimates and bacterial shedding rates determined by PFC, it is possible to make property by property recommendations for the purpose of control or eradication of OJD

Survival of Johne’s Disease in the environment : National Ovine Johne's Disease Control and Evaluation Program.

This report covers three MLA projects (TR.055, TR.055A and OJD.003) undertaken by NSW Agriculture to determine how long the sheep strain of Mycobacterium paratuberculosis survives in the environment to validate destocking recommendations for eradication of OJD. Survival of the organism was prolonged but finite. In the shade it lasted for 13 months while in the open in ungrazed pasture it lasted for 7 months. It survived for a shorter period in fully exposed pastures where grazing was simulated but for much longer in water than on pasture. These times were probably underestimates. Liming pasture did not reduce survival and moisture did not increase it. Shade was the most significant factor favouring survival. Further research is necessary to determine the mechanisms of survival, which include dormancy. Decay rates for the organism were determined for short term and long term destocking. These can be used to estimate how much time must be allowed to render pastures safe for control and eradication of OJD, respectively. When estimates of soil ingestion rates by grazing sheep are combined with within-flock OJD prevalence estimates and bacterial shedding rates determined by PFC, it is possible to make property by property recommendations for the purpose of control or eradication of OJD

Cross species transmission of Ovine Johne's Disease - Phase 2 cattle.

One thousand seven hundred and seventy four cattle from 12 properties were sampled by ELISA and faecal culture to detect Johne’s Disease. All properties had a known significant history of Johne’s disease in sheep. They were mostly selected from participants in NOJDP Trial 1.1 (a study to examine the effectiveness of an eradication strategy) and had cattle known to be susceptible to JD at the time that their properties were infected with OJD. All gave negative results on serology; only one animal from a herd of 349 gave a single positive faecal culture result, with all follow-up investigations being negative, suggesting passive transfer of the organism. Due to the small size of some of the herds tested, and the fact that no confirmed infected animals or herds were detected, it is not possible to give maximum estimate of the prevalence of OJD in exposed susceptible cattle. However, using information derived from previous investigations and some additional results in the addendum to this project report, it is known that there are at least 6 cattle herds infected with “S” strain, in NSW, at the present time

Individual animal tests for ovine Johne's disease.

Routine diagnostic tests for ovine paratuberculosis have poor sensitivity in the early stages of the disease, and transmission often occurs before detection. Currently there are no tests to accurately confirm early infection in individual sheep. Such tests are required to provide trading opportunities for producers who may have valuable stock at low risk of infection. Surgical biopsy is one means of disease detection using relatively sensitive laboratory procedures, but was unproven. 77 sheep grazing on a heavily infected farm were examined at 12, 18 and 24 months of age by histopathology and culture of biopsied ileum and mesenteric lymph nodes. Results from biopsy were compared to those from routine tests (ELISA, AGID, IFN-γ, skin testing, faecal culture and direct PCR) applied at six-monthly intervals, and to necropsy findings at three years of age. A total of 170 biopsies were performed without serious complications, and the samples collected were adequate for culture and histological assessment of paratuberculosis. Overall, 36% of sheep were shown to be uninfected at 3 years of age. Of these, 16 were uninfected at all sampling times and 11 sheep had recovered. (ie. They had been infected at an earlier sampling.) The remaining 64% of sheep were classified at necropsy as infected. Biopsy was consistently the most sensitive nonlethal technique for identification of infected sheep, although even at 36 months it detected only 2/3 of infected sheep. It may be useful as an additional tool in the management for individual valuable sheep from infected stud flocks

Cross species transmission of ovine Johnes Disease - Phase 1 : National Ovine Johne’s Disease Control and Evaluation Program.

Johne’s disease was investigated in fibre goats on several farms. The disease was caused by sheep [S] strains of Mycobacterium avium subsp. paratuberculosis. The infection appeared to be less severe than the same infection in sheep in that fewer goats than sheep became infected, and fewer goats than sheep developed obvious signs of the infection. However, infected goats shed the organism in their faeces and therefore were able to spread the infection to other goats and sheep. Therefore inclusion of goats in the control program for ovine Johne’s disease is justified. A communication program is recommended to advise producers that ovine Johne’s disease in goats may not be obvious and that testing should be undertaken to ensure disease is not present. The impact of ovine Johne’s disease on the fibre goat industry is projected not to be great due to the small number of herds likely to be infected

Anti-immunoglobulin antisera used in an ELISA to detect antibodies in barramundi Lates calcarifer to Cryptocaryon irritans

Immunoglobulins (Ig) in serum from barramundi vaccinated with bovine serum albumin (BSA) were purified by ammonium sulphate precipitation and affinity chromatography using BSA as the ligand. The BSA-binding activity of eluted putative Ig fractions was assessed by enzyme-linked immunosorbent assay (ELISA) before being pooled and characterised by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Double affinity purification did not improve the purity of the Ig preparation compared to single affinity purification. Barramundi Ig were injected into sheep to produce anti-Ig antisera which were assessed in an indirect ELISA as the secondary antibody to detect serum Ig in barramundi vaccinated with Cryptocaryon irritans theronts. Affinity-purified Ig induced a more specific reagent for use as secondary antibody in ELISA than did normal whole-barramundi sera. The heavy (H) chain of barramundi Ig had an apparent molecular weight of 70 kDa while that of the light (L) chain was 27 kDa in SDS-PAGE studies. Under non-reducing conditions 2 putative populations of Ig were identified, at 768 and 210 kDa. The N-terminal sequence of the barramundi Ig H chain showed 78% homology with channel catfish Ictalurus punctatus Ig H chain sequence

Exposure factors leading to establishment of OJD infection and clinical disease : epidemiology of OJD-1.

This study was conducted in order to provide answers for owners of OJD-infected sheep flocks who wish to minimise the economic and biological impact of the disease on their sheep enterprises. The study has demonstrated that careful management of young sheep can reduce the level of OJD in the flock and reduce the death rate. One key finding is that steps taken to limit the degree of exposure of pre-weaned lambs to infection from pastures will lead to reduced rates of severe infection in those sheep in later years. A second key finding is that continuous exposure to OJD bacteria throughout early life results in higher infection rates than exposure which is limited to either the pre-weaning or the post-weaning period alone. A critical factor in management is to provide ‘low risk’ pastures to young sheep at weaning to give them a break from exposure to infection which occurs in the lambing paddocks. We also found that weaned lambs and adult ewes remain susceptible to infection and that there is little evidence for an age-related resistance to OJD

Exposure factors leading to establishment of OJD infection and clinical disease : epidemiology of OJD-1.

This study was conducted in order to provide answers for owners of OJD-infected sheep flocks who wish to minimise the economic and biological impact of the disease on their sheep enterprises. The study has demonstrated that careful management of young sheep can reduce the level of OJD in the flock and reduce the death rate. One key finding is that steps taken to limit the degree of exposure of pre-weaned lambs to infection from pastures will lead to reduced rates of severe infection in those sheep in later years. A second key finding is that continuous exposure to OJD bacteria throughout early life results in higher infection rates than exposure which is limited to either the pre-weaning or the post-weaning period alone. A critical factor in management is to provide ‘low risk’ pastures to young sheep at weaning to give them a break from exposure to infection which occurs in the lambing paddocks. We also found that weaned lambs and adult ewes remain susceptible to infection and that there is little evidence for an age-related resistance to OJD

A Novel Use of Light Guides and Wavelength Shifting Plates for the Detection of Scintillation Photons in Large Liquid Argon Detectors

Scintillation light generated as charged particles traverse large liquid argon detectors adds valuable information to studies of weakly-interacting particles. This paper uses both laboratory measurements and cosmic ray data from the Blanche dewar facility at Fermilab to characterize the efficiency of the photon detector technology developed at Indiana University for the single phase far detector of DUNE. The efficiency of this technology was found to be 0.48% at the readout end when the detector components were characterized with laboratory measurements. A second determination of the efficiency using cosmic ray tracks is in reasonable agreement with the laboratory determination. The agreement of these two efficiency determinations supports the result that minimum ionizing muons generate ${\mathcal N}_{phot} = 40,000$ photons/MeV as they cross the LAr volume.Comment: Accepted version (without final editorial corrections

Gamma and beta frequency oscillations in response to novel auditory stimuli: A comparison of human electroencephalogram (EEG) data with in vitro models

Investigations using hippocampal slices maintained in vitro have demonstrated that bursts of oscillatory field potentials in the gamma frequency range (30-80 Hz) are followed by a slower oscillation in the beta 1 range (12-20 Hz). In this study, we demonstrate that a comparable gamma-to-beta transition is seen in the human electroencephalogram (EEG) in response to novel auditory stimuli. Correlations between gamma and beta 1 activity revealed a high degree of interdependence of synchronized oscillations in these bands in the human EEG. Evoked (stimulus-locked) gamma oscillations preceded beta 1 oscillations in response to novel stimuli, suggesting that this may be analogous to the gamma-to-beta shift observed in vitro. Beta 1 oscillations were the earliest discriminatory responses to show enhancement to novel stimuli, preceding changes in the broad-band event-related potential (mismatch negativity). Later peaks of induced beta activity over the parietal cortex were always accompanied by an underlying gamma frequency oscillation as seen in vitro. A further analogy between in vitro and human recordings was that both gamma and beta oscillations habituated markedly after the initial novel stimulus presentation