Veterinary Science - Research Publications
Now showing items 1-12 of 176
Capturing the Meaning of Free Range: The Contest between Producers, Supermarkets and Consumers for the Higher Welfare Egg Label
(Pergamon Press Ltd., 2017)
This paper shows how the Australian egg industry maintained its preferred deﬁnition of “free range” eggs in the face of a powerful consumer-oriented challenge to its labelling practices. We show how a consumer law initiative intended to enhance consumer conﬁdence and address misleading labelling of industrial-scale egg production as “free range”, was reframed through the policy consultation process, so that the primary policy problem became one of assuring industry certainty in a volatile contest for control over the governance of “free range” labelling.
Proteogenomic analysis of the total and surface-exposed proteomes of Plasmodium vivax salivary gland sporozoites
(PUBLIC LIBRARY SCIENCE, 2017-07-01)
Plasmodium falciparum and Plasmodium vivax cause the majority of human malaria cases. Research efforts predominantly focus on P. falciparum because of the clinical severity of infection and associated mortality rates. However, P. vivax malaria affects more people in a wider global range. Furthermore, unlike P. falciparum, P. vivax can persist in the liver as dormant hypnozoites that can be activated weeks to years after primary infection, causing relapse of symptomatic blood stages. This feature makes P. vivax unique and difficult to eliminate with the standard tools of vector control and treatment of symptomatic blood stage infection with antimalarial drugs. Infection by Plasmodium is initiated by the mosquito-transmitted sporozoite stage, a highly motile invasive cell that targets hepatocytes in the liver. The most advanced malaria vaccine for P. falciparum (RTS,S, a subunit vaccine containing of a portion of the major sporozoite surface protein) conferred limited protection in Phase III trials, falling short of WHO-established vaccine efficacy goals. However, blocking the sporozoite stage of infection in P. vivax, before the establishment of the chronic liver infection, might be an effective malaria vaccine strategy to reduce the occurrence of relapsing blood stages. It is also thought that a multivalent vaccine comprising multiple sporozoite surface antigens will provide better protection, but a comprehensive analysis of proteins in P. vivax sporozoites is not available. To inform sporozoite-based vaccine development, we employed mass spectrometry-based proteomics to identify nearly 2,000 proteins present in P. vivax salivary gland sporozoites. Analysis of protein post-translational modifications revealed extensive phosphorylation of glideosome proteins as well as regulators of transcription and translation. Additionally, the sporozoite surface proteins CSP and TRAP, which were recently discovered to be glycosylated in P. falciparum salivary gland sporozoites, were also observed to be similarly modified in P. vivax sporozoites. Quantitative comparison of the P. vivax and P. falciparum salivary gland sporozoite proteomes revealed a high degree of similarity in protein expression levels, including among invasion-related proteins. Nevertheless, orthologs with significantly different expression levels between the two species could be identified, as well as highly abundant, species-specific proteins with no known orthologs. Finally, we employed chemical labeling of live sporozoites to isolate and identify 36 proteins that are putatively surface-exposed on P. vivax salivary gland sporozoites. In addition to identifying conserved sporozoite surface proteins identified by similar analyses of other Plasmodium species, our analysis identified several as-yet uncharacterized proteins, including a putative 6-Cys protein with no known ortholog in P. falciparum.
Screening of the 'Stasis Box' identifies two kinase inhibitors under pharmaceutical development with activity against Haemonchus contortus
BACKGROUND: In partnership with the Medicines for Malaria Venture (MMV), we screened a collection ('Stasis Box') of 400 compounds (which have been in clinical development but have not been approved for illnesses other than neglected infectious diseases) for inhibitory activity against Haemonchus contortus, in order to attempt to repurpose some of the compounds to parasitic nematodes. METHODS: We assessed the inhibition of compounds on the motility and/or development of exsheathed third-stage (xL3s) and fourth-stage (L4) larvae of H. contortus using a whole-organism screening assay. RESULTS: In the primary screen, we identified compound MMV690767 (also known as SNS-032) that inhibited xL3 motility by ~70% at a concentration of 20 μM after 72 h as well as compound MMV079840 (also known as AG-1295), which induced a coiled xL3 phenotype, with ~50% inhibition on xL3 motility. Subsequently, we showed that SNS-032 (IC50 = 12.4 μM) and AG-1295 (IC50 = 9.92 ± 1.86 μM) had a similar potency to inhibit xL3 motility. Although neither SNS-032 nor AG-1295 had a detectable inhibitory activity on L4 motility, both compounds inhibited L4 development (IC50 values = 41.24 μM and 7.75 ± 0.94 μM for SNS-032 and AG-1295, respectively). The assessment of the two compounds for toxic effects on normal human breast epithelial (MCF10A) cells revealed that AG-1295 had limited cytotoxicity (IC50 > 100 μM), whereas SNS-032 was quite toxic to the epithelial cells (IC50 = 1.27 μM). CONCLUSIONS: Although the two kinase inhibitors, SNS-032 and AG-1295, had moderate inhibitory activity on the motility or development of xL3s or L4s of H. contortus in vitro, further work needs to be undertaken to chemically alter these entities to achieve the potency and selectivity required for them to become nematocidal or nematostatic candidates.
Ascaris phylogeny based on multiple whole mtDNA genomes
Ascaris lumbricoides and A. suum are two parasitic nematodes infecting humans and pigs, respectively. There has been considerable debate as to whether Ascaris in the two hosts should be considered a single or two separate species. Previous studies identified at least three major clusters (A, B and C) of human and pig Ascaris based on partial cox1 sequences. In the present study, we selected major haplotypes from these different clusters to characterize their whole mitochondrial genomes for phylogenetic analysis. We also undertook coalescent simulations to investigate the evolutionary history of the different Ascaris haplotypes. The topology of the phylogenetic tree based on complete mitochondrial genomic sequences was found to be similar to partial cox1 sequencing, but the support at internal nodes was higher in the former. Coalescent simulations suggested the presence of at least two divergence events: the first one occurring early in the Neolithic period which resulted in a differentiated population of Ascaris in pigs (cluster C), the second occurring more recently (~900 generations ago), resulting in clusters A and B which might have been spread worldwide by human activities.
Histochemical and morphometric characterization of broncho-pneumonia in calves caused by infection with Mycoplasma bovis
The aim of this study was to identify morphometric histological features of pneumonia caused by Mycoplasma bovis in calves. Eight three-month-old calves were infected with M. bovis and samples of their lung tissue, three weeks after exposure, compared to samples from four uninfected calves. In the uninfected animals the goblet cells were clustered in the crypt area of the epithelial folds, while in the infected calves they had migrated towards the tips of the folds and were distributed evenly throughout the folds. In infected lung tissue there was goblet cell hyperplasia and metaplasia in the bronchioles and an increased epithelial height. Goblet cell mucin in uninfected calves was acidic, but in infected calves most goblet cells contained neutral mucins. These morphometric and histochemical bronco-epithelial changes may be able to be used as markers of the severity of bovine respiratory mycoplasmosis. © 2012 Elsevier B.V.
Antimicrobials used for surgical prophylaxis by companion animal veterinarians in Australia
(ELSEVIER SCIENCE BV, 2017-05-01)
Antimicrobials are widely used in veterinary practices, but there has been no investigation into the classes of antimicrobials used or the appropriateness of their use in surgical prophylaxis. Antimicrobial usage guidelines were published by the Australian Infectious Disease Advisory Panel (AIDAP) in 2013, but there has been no investigation of compliance with them. This study aimed to investigate antimicrobial use for surgical prophylaxis in companion animal practice and assess compliance with AIDAP guidelines for selected conditions by conducting a cross-sectional study of antimicrobial usage patterns of Australian veterinarians using an online questionnaire. Information solicited included: details of the respondent, the frequency with which antimicrobials were used for specific surgical conditions (including dose and duration) and practice antimicrobial use policies and sources of information about antimicrobial drugs and their uses. A total of 886 members of the Australian veterinary profession completed the survey. Few (22%) reported that their practice that had an antimicrobial use policy. Generally, the choice of antimicrobial drug was appropriate for the given surgical conditions. There was poor compliance with AIDAP guidelines for non-use of antimicrobials for routine neutering. Veterinarians caring solely for companion animals had higher odds of optimal compliance with guidelines than veterinarians in mixed species practices (OR 1.4, 95%CI 1.1-1.9). Recent graduates (>2011) had lower odds of compliance than older graduates (OR 0.8, 95%CI 0.6-0.9). The findings suggest that antimicrobial use guidelines need to be expanded and promoted to improve the responsible use of antimicrobials in small animal practice in Australia.
Evaluation of the Biocompatibility of Polypyrrole Implanted Subdurally in GAERS
(WILEY-V C H VERLAG GMBH, 2017-05-01)
This blinded controlled prospective randomized study investigates the biocompatibility of polypyrrole (PPy) polymer that will be used for intracranial triggered release of anti-epileptic drugs (AEDs). Three by three millimeters PPy are implanted subdurally in six adult female genetic absence epilepsy rats from Strasbourg. Each rat has a polymer implanted on one side of the cortex and a sham craniotomy performed on the other side. After a period of seven weeks, rats are euthanized and parallel series of coronal sections are cut throughout the implant site. Four series of 15 sections are histological (hematoxylin and eosin) and immunohistochemically (neuron-specific nuclear protein, glial fibrillary acidic protein, and anti-CD68 antibody) stained and evaluated by three investigators. The results show that implanted PPy mats do not induce obvious inflammation, trauma, gliosis, and neuronal toxicity. Therefore the authors conclude the PPy used offer good histocompatibility with central nervous system cells and that PPy sheets can be used as intracranial, AED delivery implant.
Mitochondrial genomic comparison of Clonorchis sinensis from South Korea with other isolates of this species
(ELSEVIER SCIENCE BV, 2017-07-01)
Clonorchiasis is a neglected tropical disease that affects >35 million people mainly in China, Vietnam, South Korea and some parts of Russia. The disease-causing agent, Clonorchis sinensis, is a liver fluke of humans and other piscivorous animals, and has a complex aquatic life cycle involving snails and fish intermediate hosts. Chronic infection in humans causes liver disease and associated complications including malignant bile duct cancer. Central to control and to understanding the epidemiology of this disease is knowledge of the specific identity of the causative agent as well as genetic variation within and among populations of this parasite. Although most published molecular studies seem to suggest that C. sinensis represents a single species and that genetic variation within the species is limited, karyotypic variation within C. sinensis among China, Korea (2n=56) and Russian Far East (2n=14) suggests that this taxon might contain sibling species. Here, we assessed and applied a deep sequencing-bioinformatic approach to sequence and define a reference mitochondrial (mt) genome for a particular isolate of C. sinensis from Korea (Cs-k2), to confirm its specific identity, and compared this mt genome with homologous data sets available for this species. Comparative analyses revealed consistency in the number and structure of genes as well as in the lengths of protein-coding genes, and limited genetic variation among isolates of C. sinensis. Phylogenetic analyses of amino acid sequences predicted from mt genes showed that representatives of C. sinensis clustered together, with absolute nodal support, to the exclusion of other liver fluke representatives, but sub-structuring within C. sinensis was not well supported. The plan now is to proceed with the sequencing, assembly and annotation of a high quality draft nuclear genome of this defined isolate (Cs-k2) as a basis for a detailed investigation of molecular variation within C. sinensis from disparate geographical locations in parts of Asia and to prospect for cryptic species.
Genetic diversity in the C-terminus of merozoite surface protein 1 among Plasmodium knowlesi isolates from Selangor and Sabah Borneo, Malaysia
Plasmodium knowlesi, a malaria parasite of macaques, has emerged as an important parasite of humans. Despite the significance of P. knowlesi malaria in parts of Southeast Asia, very little is known about the genetic variation in this parasite. Our aim here was to explore sequence variation in a molecule called the 42kDa merozoite surface protein-1 (MSP-1), which is found on the surface of blood stages of Plasmodium spp. and plays a key role in erythrocyte invasion. Several studies of P. falciparum have reported that the C-terminus (a 42kDa fragment) of merozoite surface protein-1 (MSP-142; consisting of MSP-119 and MSP-133) is a potential candidate for a malaria vaccine. However, to date, no study has yet investigated the sequence diversity of the gene encoding P. knowlesi MSP-142 (comprising Pk-msp-119 and Pk-msp-133) among isolates in Malaysia. The present study explored this aspect. Twelve P. knowlesi isolates were collected from patients from hospitals in Selangor and Sabah Borneo, Malaysia, between 2012 and 2014. The Pk-msp-142 gene was amplified by PCR and directly sequenced. Haplotype diversity (Hd) and nucleotide diversity (л) were studied among the isolates. There was relatively high genetic variation among P. knowlesi isolates; overall Hd and л were 1±0.034 and 0.01132±0.00124, respectively. A total of nine different haplotypes related to amino acid alterations at 13 positions, and the Pk-MSP-119 sequence was found to be more conserved than Pk-msp-133. We have found evidence for negative selection in Pk-msp-42 as well as the 33kDa and 19kDa fragments by comparing the rate of non-synonymous versus synonymous substitutions. Future investigations should study large numbers of samples from disparate geographical locations to critically assess whether this molecule might be a potential vaccine target for P. knowlesi.
An automated, multiplex-tandem PCR platform for the diagnosis of gastrointestinal nematode infections in cattle: An Australian-European validation study
(ELSEVIER SCIENCE BV, 2017-05-30)
Detecting the genera and species of gastrointestinal (GI) nematode infections in faecal samples obtained from cattle requires the incubation of faeces ('larval culture') followed by identification of the third-stage larvae that are harvested after 10-14days. Substantial research in the development of PCR-based methods for the rapid and specific identification GI nematodes has been conducted for small ruminants, whilst only few such assays have been developed for cattle. In the present paper we describe the development of an automated, robotic PCR platform for the detection and genus and/or species-specific identification of GI nematodes from bovine faecal samples. This test was then validated using samples from different regions of three countries (Australia, Belgium and Scotland). The PCR platform was found to be highly sensitive and specific for the identification of the important GI nematodes in naturally infected cattle (both estimates >90%). The PCR platform can also estimate the percentage of genera or species present in a mixed-species infection, and was found superior to larval culture in terms of speed (1-2days versus 1-2 weeks for culture), sensitivity and specificity. The PCR was simple to use and the operator requires no knowledge or experience to identify the nematodes present, compared to larval culture where even experienced operators can make substantial errors due to considerable overlap in the published characteristics of key species.