Dental clinicians' perceptions on the use of tele-dentistry consultations during COVID-19 within public dental clinics in Sydney, Australia.

BACKGROUND: Although well accepted by clinicians and patients, teledentistry is not currently a widely used model of care within Australian public oral health services. This qualitative study aimed to review and evaluate dental clinicians' perceptions, by determining the acceptability and appropriateness of teledentistry as a model of care. METHODS: A purposive sample of 12 public dental practitioners employed by a Local Health District in Sydney, and who had participated in teledentistry consultations, were recruited to participate in focus groups. Focus group discussions were transcribed verbatim and subjected to thematic analysis. RESULTS: Teledentistry was a novel concept for most participants and was well accepted. Participants valued the use of a standardized consultation template as well as effective communication with other dental clinicians to support the practice of teledentistry. However, many found attempting contact with patients over the telephone difficult as well as the perceived patient frustration with the administration process and technological difficulties experienced. CONCLUSION: Teledentistry has the potential for growth and expansion in the public health system. From the opinions in this study, the authors propose further research is needed into the efficacy of teledentistry to assist with the development of a model of care that would be beneficial for dental clinicians and their patients. © 2023 Australian Dental Association.

Factors associated with bovine respiratory disease case fatality in feedlot cattle.

Bovine respiratory disease (BRD) is the primary cause of morbidity and mortality in cattle feedlots. There is a need to understand what animal health and production factors are associated with increased mortality risk due to BRD. The aim of the present study was to explore factors associated with BRD case fatality in feedlot cattle. Four pens totaling 898 steers were monitored daily for visual signs of BRD such as difficult breathing and coughing, and animals exhibiting signs of BRD were taken to the hospital shed for further examination and clinical measures. Blood samples were obtained at feedlot entry and at time of first BRD pull from animals diagnosed with BRD (n = 121) and those that died due to BRD confirmed by postmortem examination (n = 16; 13.2% case fatality rate). Mixed-effects linear regression models were used to estimate differences in animal health and production factors and the relative concentrations of 34 identified blood metabolites between animals that survived versus those that died. Generalized linear mixed-effects models were used to obtain the odds of being seronegative (at both feedlot entry and first BRD pull) to 5 BRD viruses and having a positive nasal swab result at the time of first pull in died and survived animals. Animals that died from BRD had lower average daily gain (ADG), reduced weight at first BRD pull, higher visual BRD scores and received more treatments for BRD compared with animals that survived BRD (P < 0.05). The odds of being seronegative for bovine viral diarrhea virus 1 (BVDV-1) were 5.66 times higher for animals that died compared with those that survived (P = 0.013). The odds of having a positive bovine coronavirus nasal swab result were 13.73 times higher in animals that died versus those that survived (P = 0.007). Animals that died from BRD had higher blood concentrations of α glucose chain, ß-hydroxybutyrate, leucine, phenylalanine, and pyruvate compared with those that survived (P < 0.05). Animals that died from BRD had lower concentrations of acetate, citrate, and glycine compared with animals that survived (P < 0.05). The results of the current study suggest that ADG to first BRD pull, weight at first BRD pull, visual BRD score, the number of BRD treatments, seronegativity to BVDV-1, virus positive to BCoV nasal swab, and that certain blood metabolites are associated with BRD case fatality risk. The ability of these measures to predict the risk of death due to BRD needs further research.

Genome Sequences of Two Marsupial Simplex Viruses, Macropodid Alphaherpesviruses 2 and 4.

We present the genome sequences of macropodid alphaherpesviruses 2 and 4, two closely related pathogens of macropods. Both encoded 68 nonredundant open reading frames (ORFs) and share 90.6% genome-wide nucleotide identity. These viruses are associated with fatal outbreaks of disease in multiple marsupial species. These sequences will be important for the development of new diagnostic tools.

Mycoplasma bovis and bovine respiratory disease: A risk factor study in Australian feeder cattle.

Mycoplasma bovis can be a bacterial inhabitant of the upper respiratory tract of healthy bovines. In body regions other that the upper respiratory tract however, M. bovis is associated with a number of clinical syndromes such as bovine respiratory disease (BRD). This study used two enzyme-linked immunosorbent assays to assess the sero-status of M. bovis-specific antibodies in Australian feeder cattle at the time of feedlot induction and at approximately 42 days on feed (follow-up). The apparent sero-prevalence of M. bovis-specific antibody at induction was estimated to be 3.5% (95% confidence interval [CI] 2.0-5.0%, 47/1354) and 25.3% (95% CI 21.9-28.8%, 343/1354) at follow-up. Exposure to M. bovis between induction and follow-up as demonstrated by an increase in serum antibodies was estimated to be 19.4% (95% CI 16.2-22.6%, 261/1349). Risk factors associated with sero-positivity at feedlot induction included the region where animals were 28 days prior to induction and saleyard exposure at least 27 days prior to induction. Risk factors associated with a sero-increase between induction and follow-up included breed, source region and access to water shared with an adjoining pen of animals. Of these, shared pen water was considered the most important (odds ratio [OR] 3.3, 95% CI 1.5-7.4, p = 0.003). Animals exposed to M. bovis between induction and follow-up were at a substantially increased risk of BRD (OR 2.2, 95% CI 1.4-3.4, p = 0.001). This is the first Australian study that has identified risk factors for M. bovis sero-positivity and sero-increase and shown an association between sero-increase and the risk of BRD in the feeder cattle population. These findings suggest that M. bovis is a significant pathogen in the Australian feeder cattle population. In addition, identification of defined risk factors associated with an increased risk of exposure to M. bovis can assist in the development of targeted control measures to reduce the economic impact of M. bovis associated disease and BRD in feeder cattle.

Cold adaptation and replicable microbial community development during long-term low-temperature anaerobic digestion treatment of synthetic sewage.

The development and activity of a cold-adapting microbial community was monitored during low-temperature anaerobic digestion (LtAD) treatment of wastewater. Two replicate hybrid anaerobic sludge bed-fixed-film reactors treated a synthetic sewage wastewater at 12°C, at organic loading rates of 0.25-1.0 kg chemical oxygen demand (COD) m-3 d-1, over 889 days. The inoculum was obtained from a full-scale anaerobic digestion reactor, which was operated at 37°C. Both LtAD reactors readily degraded the influent with COD removal efficiencies regularly exceeding 78% for both the total and soluble COD fractions. The biomass from both reactors was sampled temporally and tested for activity against hydrolytic and methanogenic substrates at 12°C and 37°C. Data indicated that significantly enhanced low-temperature hydrolytic and methanogenic activity developed in both systems. For example, the hydrolysis rate constant (k) at 12°C had increased 20-30-fold by comparison to the inoculum by day 500. Substrate affinity also increased for hydrolytic substrates at low temperature. Next generation sequencing demonstrated that a shift in a community structure occurred over the trial, involving a 1-log-fold change in 25 SEQS (OTU-free approach) from the inoculum. Microbial community structure changes and process performance were replicable in the LtAD reactors.

Population-level effects of risk factors for bovine respiratory disease in Australian feedlot cattle.

Results obtained from a nationwide longitudinal study were extended to estimate the population-level effects of selected risk factors on the incidence of bovine respiratory disease (BRD) during the first 50days at risk in medium-sized to large Australian feedlots. Population attributable fractions (PAF) and population attributable risks (PAR) were used to rank selected risk factors in order of importance from the perspective of the Australian feedlot industry within two mutually exclusive categories: 'intervention' risk factors had practical strategies that feedlot managers could implement to avoid exposure of cattle to adverse levels of the risk factor and a precise estimate of the population-level effect while 'others' did not. An alternative method was also used to quantify the expected effects of simultaneously preventing exposure to multiple management-related factors whilst not changing exposure to factors that were more difficult to modify. The most important 'intervention' risk factors were shared pen water (PAF: 0.70, 95% credible interval: 0.45-0.83), breed (PAF: 0.67, 95% credible interval: 0.54-0.77), the animal's prior lifetime history of mixing with cattle from other herds (PAF: 0.53, 95% credible interval: 0.30-0.69), timing of the animal's move to the vicinity of the feedlot (PAF: 0.45, 95% credible interval: 0.17-0.68), the presence of Bovine viral diarrhoea virus 1 (BVDV-1) in the animal's cohort (PAF: 0.30, 95% credible interval: 0.04-0.50), the number of study animals in the animal's group 13days before induction (PAF: 0.30, 95% credible interval: 0.10-0.44) and induction weight (PAF: 0.16, 95% credible interval: 0.09-0.23). Other important risk factors identified and prioritised for further research were feedlot region, season of induction and cohort formation patterns. An estimated 82% of BRD incidence was attributable to management-related risk factors, whereby the lowest risk category of a composite management-related variable comprised animals in the lowest risk category of at least four of the five component variables (shared pen water, mixing, move timing, BVDV-1 in the cohort and the number of animals in the animal's group-13). This indicated that widespread adoption of appropriate interventions including ensuring pen water is not shared between pens, optimising animal mixing before induction, timing of the animal's move to the vicinity of the feedlot, and group size prior to placing animals in feedlot pens, and avoiding BVDV-1 in cohorts could markedly reduce the incidence of BRD in medium-sized to large Australian feedlots.

Alphaherpesvirus-associated disease in greater bilbies (Macrotis lagotis).

CASE REPORT: A captive breeding colony of 9 greater bilbies (Macrotis lagotis) exhibited mild upper respiratory signs and sudden deaths with 100% mortality over a 2-week period. Histologically, acute necrotising and erosive epithelial lesions throughout the upper respiratory system and bronchi were associated with eosinophilic intranuclear inclusion bodies. Inclusions were also present in hepatocytes and adrenocortical cells, but were not always associated with necrosis. Transmission electron microscopy of lung sections revealed nucleocapsids forming arrays within some nuclei. A pan-herpesvirus PCR yielded a 440-bp product, with sequencing confirming homology with the alphaherpesviruses. Viral culture in a marsupial cell line resulted in cytopathic effect consistent with an alphaherpesvirus. CONCLUSION: This is the first report of a herpesvirus-associated disease in greater bilbies.

Associations between feedlot management practices and bovine respiratory disease in Australian feedlot cattle.

Bovine respiratory disease (BRD) is the major cause of clinical disease and death in feedlot cattle. A prospective longitudinal study was conducted in a population of Australian feedlot cattle to assess associations between factors related to feedlot management and risk of BRD. In total, 35,131 animals in 170 pens (cohorts) inducted into 14 feedlots were included in statistical analyses. Causal diagrams were used to inform model building to allow separate estimation of total and direct effects. Multilevel mixed effects logistic regression models were fitted within the Bayesian framework. The placement of pen water troughs such that they could be accessed by animals in adjoining pens was associated with markedly increased risk of BRD (OR 4.3, 95% credible interval: 1.4-10.3). Adding animals to pens over multiple days was associated with increased risk of BRD across all animals in those pens compared to placing all animals in the pen on a single day (total effect: OR 1.9, 95% credible interval: 1.2-2.8). The much attenuated direct effect indicated that this was primarily mediated via factors on indirect pathways so it may be possible to ameliorate the adverse effects of adding animals to pens over multiple days by altering exposure to these intervening factors (e.g. mixing history). In pens in which animals were added to the pen over multiple days, animals added ≥7 days (OR: 0.7, credible interval: 0.5-0.9) or 1-6 days (OR: 0.8, credible interval: 0.7-1.0) before the last animal was added were at modestly reduced risk of BRD compared to the animals that were added to the pen on the latest day. Further research is required to disentangle effects of cohort formation patterns at animal-level and higher levels on animal-level risk of BRD. Vaccination against Bovine herpesvirus 1 at feedlot entry was investigated but results were inconclusive and further research is required to evaluate vaccine efficacy. We conclude that there are practical interventions available to feedlot managers to reduce the risk of cattle developing BRD at the feedlot. We recommend placement of water troughs in feedlot pens so that they cannot be accessed by animals in adjoining pens. Further research is required to identify practical and cost-effective management strategies that allow longer adaption times for cattle identified prior to induction as being at higher risk of developing BRD.

Associations between prior management of cattle and risk of bovine respiratory disease in feedlot cattle.

Bovine respiratory disease (BRD) is the major cause of clinical disease and death in feedlot populations worldwide. A longitudinal study was conducted to assess associations between risk factors related to on-farm management prior to transport to the feedlot and risk of BRD in a population of feedlot beef cattle sourced from throughout the cattle producing regions of Australia. Exposure variables were derived from questionnaire data provided by farmers supplying cattle (N=10,721) that were a subset of the population included in a nationwide prospective study investigating numerous putative risk factors for BRD. Causal diagrams were used to inform model building to allow estimation of effects of interest. Multilevel mixed effects logistic regression models were fitted within the Bayesian framework. Animals that were yard weaned were at reduced risk (OR: 0.7, 95% credible interval: 0.5-1.0) of BRD at the feedlot compared to animals immediately returned to pasture after weaning. Animals that had previously been fed grain (OR: 0.6, 95% credible interval: 0.3-1.1) were probably at reduced risk of BRD at the feedlot compared to animals not previously fed grain. Animals that received prior vaccinations against Bovine viral diarrhoea virus 1 (OR: 0.8, 95% credible interval: 0.5-1.1) or Mannheimia haemolytica (OR: 0.8, 95% credible interval: 0.6-1.0) were also probably at reduced risk compared to non-vaccinated animals. The results of this study confirm that on-farm management before feedlot entry can alter risk of BRD after beef cattle enter feedlots.

Associations between exposure to viruses and bovine respiratory disease in Australian feedlot cattle.

Bovine respiratory disease (BRD) is the most important cause of clinical disease and death in feedlot cattle. Respiratory viral infections are key components in predisposing cattle to the development of this disease. To quantify the contribution of four viruses commonly associated with BRD, a case-control study was conducted nested within the National Bovine Respiratory Disease Initiative project population in Australian feedlot cattle. Effects of exposure to Bovine viral diarrhoea virus 1 (BVDV-1), Bovine herpesvirus 1 (BoHV-1), Bovine respiratory syncytial virus (BRSV) and Bovine parainfluenza virus 3 (BPIV-3), and to combinations of these viruses, were investigated. Based on weighted seroprevalences at induction (when animals were enrolled and initial samples collected), the percentages of the project population estimated to be seropositive were 24% for BoHV-1, 69% for BVDV-1, 89% for BRSV and 91% for BPIV-3. For each of the four viruses, seropositivity at induction was associated with reduced risk of BRD (OR: 0.6-0.9), and seroincrease from induction to second blood sampling (35-60 days after induction) was associated with increased risk of BRD (OR: 1.3-1.5). Compared to animals that were seropositive for all four viruses at induction, animals were at progressively increased risk with increasing number of viruses for which they were seronegative; those seronegative for all four viruses were at greatest risk (OR: 2.4). Animals that seroincreased for one or more viruses from induction to second blood sampling were at increased risk (OR: 1.4-2.1) of BRD compared to animals that did not seroincrease for any viruses. Collectively these results confirm that prior exposure to these viruses is protective while exposure at or after feedlot entry increases the risk of development of BRD in feedlots. However, the modest increases in risk associated with seroincrease for each virus separately, and the progressive increases in risk with multiple viral exposures highlights the importance of concurrent infections in the aetiology of the BRD complex. These findings indicate that, while efficacious vaccines could aid in the control of BRD, vaccination against one of these viruses would not have large effects on population BRD incidence but vaccination against multiple viruses would be expected to result in greater reductions in incidence. The findings also confirm the multifactorial nature of BRD development, and indicate that multifaceted approaches in addition to efficacious vaccines against viruses will be required for substantial reductions in BRD incidence.

Effects of exposure to Bovine viral diarrhoea virus 1 on risk of bovine respiratory disease in Australian feedlot cattle.

Viruses play a key role in the complex aetiology of bovine respiratory disease (BRD). Bovine viral diarrhoea virus 1 (BVDV-1) is widespread in Australia and has been shown to contribute to BRD occurrence. As part of a prospective longitudinal study on BRD, effects of exposure to BVDV-1 on risk of BRD in Australian feedlot cattle were investigated. A total of 35,160 animals were enrolled at induction (when animals were identified and characteristics recorded), held in feedlot pens with other cattle (cohorts) and monitored for occurrence of BRD over the first 50days following induction. Biological samples collected from all animals were tested to determine which animals were persistently infected (PI) with BVDV-1. Data obtained from the Australian National Livestock Identification System database were used to determine which groups of animals that were together at the farm of origin and at 28days prior to induction (and were enrolled in the study) contained a PI animal and hence to identify animals that had probably been exposed to a PI animal prior to induction. Multi-level Bayesian logistic regression models were fitted to estimate the effects of exposure to BVDV-1 on the risk of occurrence of BRD. Although only a total of 85 study animals (0.24%) were identified as being PI with BVDV-1, BVDV-1 was detected on quantitative polymerase chain reaction in 59% of cohorts. The PI animals were at moderately increased risk of BRD (OR 1.9; 95% credible interval 1.0-3.2). Exposure to BVDV-1 in the cohort was also associated with a moderately increased risk of BRD (OR 1.7; 95% credible interval 1.1-2.5) regardless of whether or not a PI animal was identified within the cohort. Additional analyses indicated that a single quantitative real-time PCR test is useful for distinguishing PI animals from transiently infected animals. The results of the study suggest that removal of PI animals and/or vaccination, both before feedlot entry, would reduce the impact of BVDV-1 on BRD risk in cattle in Australian feedlots. Economic assessment of these strategies under Australian conditions is required.

Associations between animal characteristic and environmental risk factors and bovine respiratory disease in Australian feedlot cattle.

A prospective longitudinal study was conducted in a population of Australian feedlot cattle to assess associations between animal characteristic and environmental risk factors and risk of bovine respiratory disease (BRD). Animal characteristics were recorded at induction, when animals were individually identified and enrolled into study cohorts (comprising animals in a feedlot pen). Environmental risk factors included the year and season of induction, source region and feedlot region and summary variables describing weather during the first week of follow-up. In total, 35,131 animals inducted into 170 cohorts within 14 feedlots were included in statistical analyses. Causal diagrams were used to inform model building and multilevel mixed effects logistic regression models were fitted within the Bayesian framework. Breed, induction weight and season of induction were significantly and strongly associated with risk of BRD. Compared to Angus cattle, Herefords were at markedly increased risk (OR: 2.0, 95% credible interval: 1.5-2.6) and tropically adapted breeds and their crosses were at markedly reduced risk (OR: 0.5, 95% credible interval: 0.3-0.7) of developing BRD. Risk of BRD declined with increased induction weight, with cattle in the heaviest weight category (≥480kg) at moderately reduced risk compared to cattle weighing <400kg at induction (OR: 0.6, 95% credible interval: 0.5-0.7). Animals inducted into feedlots during summer (OR: 2.4, 95% credible interval: 1.4-3.8) and autumn (OR: 2.1, 95% credible interval: 1.2-3.2) were at markedly increased risk compared to animals inducted during spring. Knowledge of these risk factors may be useful in predicting BRD risk for incoming groups of cattle in Australian feedlots. This would then provide the opportunity for feedlot managers to tailor management strategies for specific subsets of animals according to predicted BRD risk.

Understanding the molecular basis of disease is crucial to improving the design and construction of herpesviral vectors for veterinary vaccines.

Viral infections are associated with production losses in many animal production industries. Important examples of this are Marek's disease (MD) and bovine respiratory disease (BRD) which are significant issues in the chicken and cattle industries, respectively. Viruses play key roles in MD and BRD development and consequently have also been utilised in vaccination strategies to control these diseases. Despite the widespread availability and use of vaccines to control these diseases both are still major issues for their respective industries. Here the dual role of members of viruses from the family Herpesviridae in causation and control of MD and BRD will be discussed. The technologies that may lead to the development of improved vaccines to provide more sustainable control of MD and BRD will also be identified.

Risk factors for bovine respiratory disease in Australian feedlot cattle: use of a causal diagram-informed approach to estimate effects of animal mixing and movements before feedlot entry.

A nationwide longitudinal study was conducted to investigate risk factors for bovine respiratory disease (BRD) in cattle in Australian feedlots. After induction (processing), cattle were placed in feedlot pens (cohorts) and monitored for occurrence of BRD over the first 50 days on feed. Data from a national cattle movement database were used to derive variables describing mixing of animals with cattle from other farms, numbers of animals in groups before arrival at the feedlot, exposure of animals to saleyards before arrival at the feedlot, and the timing and duration of the animal's move to the vicinity of the feedlot. Total and direct effects for each risk factor were estimated using a causal diagram-informed process to determine covariates to include in four-level Bayesian logistic regression models. Mixing, group size and timing of the animal's move to the feedlot were important predictors of BRD. Animals not mixed with cattle from other farms prior to 12 days before induction and then exposed to a high level of mixing (≥4 groups of animals mixed) had the highest risk of developing BRD (OR 3.7) compared to animals mixed at least 4 weeks before induction with less than 4 groups forming the cohort. Animals in groups formed at least 13 days before induction comprising 100 or more (OR 0.5) or 50-99 (OR 0.8) were at reduced risk compared to those in groups of less than 50 cattle. Animals moved to the vicinity of the feedlot at least 27 days before induction were at reduced risk (OR 0.4) compared to cattle undergoing short-haul transportation (<6h) to the feedlot within a day of induction, while those experiencing longer transportation durations (6h or more) within a day of induction were at slightly increased risk (OR 1.2). Knowledge of these risk factors could potentially be used to inform management decisions to reduce the risk of BRD in feedlot cattle.

Is Mycoplasma bovis a missing component of the bovine respiratory disease complex in Australia?

BACKGROUND: Bovine respiratory disease complex (BRDC) is a multi-factorial disease in which numerous factors, such as animal management, pathogen exposure and environmental conditions, contribute to the development of acute respiratory illness in feedlot cattle. The role of specific pathogens in the development of BRDC has been difficult to define because of the complex nature of the disease and the presence of implicated bacterial pathogens in the upper respiratory tract of healthy animals. Mycoplasma bovis is an important pathogen of cattle and recognised as a major contributor to cases of mastitis, caseonecrotic bronchopneumonia, arthritis and otitis media. To date, the role of M. bovis in the development of BRDC of Australian feeder cattle has not been investigated. METHODS: In this review, the current literature pertaining to the role of M. bovis in BRDC is evaluated. In addition, preliminary data are presented that identify M. bovis as a potential contributor to BRDC in Australian feedlots, which has not been considered previously. RESULTS AND CONCLUSION: The preliminary results demonstrate detection of M. bovis in samples from all feedlots studied. When considered in the context of the reviewed literature, they support the inclusion of M. bovis on the list of pathogens to be considered during investigations into BRDC in Australia.

In vivo delivery of bovine viral diahorrea virus, E2 protein using hollow mesoporous silica nanoparticles.

Our work focuses on the application of mesoporous silica nanoparticles as a combined delivery vehicle and adjuvant for vaccine applications. Here we present results using the viral protein, E2, from bovine viral diarrhoea virus (BVDV). BVDV infection occurs in the target species of cattle and sheep herds worldwide and is therefore of economic importance. E2 is a major immunogenic determinant of BVDV and is an ideal candidate for the development of a subunit based nanovaccine using mesoporous silica nanoparticles. Hollow type mesoporous silica nanoparticles with surface amino functionalisation (termed HMSA) were characterised and assessed for adsorption and desorption of E2. A codon-optimised version of the E2 protein (termed Opti-E2) was produced in Escherichia coli. HMSA (120 nm) had an adsorption capacity of 80 µg Opti-E2 per mg HMSA and once bound E2 did not dissociate from the HMSA. Immunisation studies in mice with a 20 µg dose of E2 adsorbed to 250 µg HMSA was compared to immunisation with Opti-E2 (50 µg) together with the traditional adjuvant Quillaja saponaria Molina tree saponins (QuilA, 10 µg). The humoral responses with the Opti-E2/HMSA nanovaccine although slightly lower than those obtained for the Opti-E2 + QuilA group demonstrated that HMSA particles are an effective adjuvant that stimulated E2-specific antibody responses. Importantly the cell-mediated immune responses were consistently high in all mice immunised with Opti-E2/HMSA nanovaccine formulation. Therefore we have shown the Opti-E2/HMSA nanoformulation acts as an excellent adjuvant that gives both T-helper 1 and T-helper 2 mediated responses in a small animal model. This study has provided proof-of-concept towards the development of an E2 subunit nanoparticle based vaccine.

The hydrolysis and biogas production of complex cellulosic substrates using three anaerobic biomass sources.

In this study, the ability of various sludges to digest a diverse range of cellulose and cellulose-derived substrates was assessed at different temperatures to elucidate the factors affecting hydrolysis. For this purpose, the biogas production was monitored and the specific biogas activity (SBA) of the sludges was employed to compare the performance of three anaerobic sludges on the degradation of a variety of complex cellulose sources, across a range of temperatures. The sludge with the highest performance on complex substrates was derived from a full-scale bioreactor treating sewage at 37 °C. Hydrolysis was the rate-limiting step during the degradation of complex substrates. No activity was recorded for the synthetic cellulose compound carboxymethylcellulose (CMC) using any of the sludges tested. Increased temperature led to an increase in hydrolysis rates and thus SBA values. The non-granular nature of the mesophilic sludge played a positive role in the hydrolysis of solid substrates, while the granular sludges proved more effective on the degradation of soluble compounds.

Temperature effects on the trophic stages of perennial rye grass anaerobic digestion.

Continuous Stirred Tank Reactors (CSTRs), operated in batch mode, were used to evaluate the feasibility of psychrophilic (low temperature) digestion of perennial rye grass in a long term experiment (150 days) for the first time. The reactors were operated in parallel at 3 different temperatures, 10, 15 and 37 degrees C. Hydrolysis, acidification and methanogenesis were assessed by VS degradation, by soluble chemical oxygen demand (SCOD) and volatile fatty acids (VFA) production, and by methane production, respectively. Hydrolysis was the rate-limiting step at all temperatures and the rates and extent of hydrolysis were considerably lower at 15 and 10 degrees C, than at 37 degrees C. The total VS degradation was 53%, 34% and 19% at 37, 15 and 10 degrees C, respectively. Acidification was not affected by temperature and VFA production and consumption was balanced in all cases, except at 10 degrees C. Methane yields were 0.215 m3 CH4 kg(-1) VS(-1) added, 0.160 m3 CH4 kg(-1) VS(-1) added and 0.125 m3 CH4 kg(-1) VS(-1) added at 37, 15 and 10 degrees C, respectively. Methanogenesis was not strongly affected at 15 C but it became rate-limiting at 10 degrees C. Overall, the solid degradation and methane production performance under psychrophilic conditions was encouraging and greater than previously reported. Considering the non-acclimated, mesophilic nature of the inoculum, there are grounds to believe that low-temperature anaerobic digestion of grass could be feasible if coupled to efficient hydrolysis of the biomass.

A Lucilia cuprina excretory-secretory protein inhibits the early phase of lymphocyte activation and subsequent proliferation.

The development of a protective immune response in sheep towards the presence of the larval stage of Lucilia cuprina has not been reported in the field. Upon investigation of the effects of larval excretory/secretory material on ovine T lymphocyte proliferation, we isolated a 56 kDa protein capable of inhibiting lymphocyte proliferation by at least 70%, compared with that in the presence of mitogen alone. This protein inhibited proliferation induced through cross-linking of the T-cell receptor as well as proliferation induced pharmacologically through the stimulation of the protein kinase C (PKC) pathway. The protein, named blowfly larval immunosuppressive protein (BLIP), was shown to bind directly to lymphocytes. Further investigation revealed that the BLIP prevented a proportion of lymphocytes from entering the first division following stimulation, by affecting the early events in lymphocyte activation. Subsequently, the BLIP reduced CD25 expression on T lymphocytes, reduced IL-2 mRNA expression, in addition to IFN-gamma, IL-4, IL-10 and IL-13 mRNA expression. Conversely, TNF-alpha and TGF-beta gene expression was up-regulated in response to the BLIP. These effects suggest suboptimal activation of T lymphocytes in the presence of the BLIP, and we propose that the BLIP presents an effective immune evasion tactic for the larvae of L. cuprina.

Cultivation of low-temperature (15 degrees C), anaerobic, wastewater treatment granules.

AIMS: Anaerobic sludge granules underpin high-rate waste-to-energy bioreactors. Granulation is a microbiological phenomenon involving the self-immobilization of several trophic groups. Low-temperature anaerobic digestion of wastes is of intense interest because of the economic advantages of unheated bioenergy production technologies. However, low-temperature granulation of anaerobic sludge has not yet been demonstrated. The aims of this study were to (i) investigate the feasibility of anaerobic sludge granulation in cold (15 degrees C) bioreactors and (ii) observe the development of methanogenic activity and microbial community structure in developing cold granules. METHODS AND RESULTS: One mesophilic (R1; 37 degrees C) and two low-temperature (R2 and R3, 15 degrees C) laboratory-scale, expanded granular sludge bed bioreactors were seeded with crushed (diameter <0.4 mm) granules and were fed a glucose-based wastewater for 194 days. Bioreactor performance was assessed by chemical oxygen demand removal, biogas production, granule growth and temporal methanogenic activity. Granulation was observed in R2 and R3 (up to 33% of the sludge). Elevated hydrogenotrophic methanogenesis was observed in psychrophilically cultivated biomass, but acetoclastic methanogenic activity was also retained. Denaturing gradient gel electrophoresis of archaeal 16S rRNA gene fragments indicated that a distinct community was associated with developing and mature granules in the low-temperature (LT) bioreactors. CONCLUSIONS: Granulation was observed at 15 degrees C in anaerobic bioreactors and was associated with H(2)/CO(2)-mediated methanogenesis and distinct community structure development. SIGNIFICANCE AND IMPACT OF THE STUDY: Granulation underpins high-rate anaerobic waste treatment bioreactors. Most LT bioreactor trials have employed mesophilic seed sludge, and granulation <20 degrees C was not previously documented.