Publications by authors named "Thi T H Van"

Article Synopsis
  • The study investigated how geography affects the cloacal microbiota of two Australian freshwater turtle species, Chelodina longicollis and Emydura macquarii, based on the anthropogenic impact of their environments.
  • Using 16S rRNA gene amplicon sequencing, the researchers assessed the microbiota composition, structure, and diversity in 93 turtles from five different locations.
  • Results indicated that C. longicollis from disturbed areas had lower microbial diversity compared to those from less affected environments, while E. macquarii showed consistent microbiota across locations, highlighting the impact of environmental factors on microbial communities.
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Chickens in Australia have recently been identified with symptoms and morphological findings including spondylitis attributed to pathogenic Enterococcus cecorum. Notably, there is limited information on clinical E. cecorum strains in Australia.

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Article Synopsis
  • Various species of campylobacters, including one causing spotty liver disease (SLD) in poultry, pose significant health and economic challenges, leading to high mortality and decreased egg production.
  • Innovative genetic tools and methods were developed for manipulating the pathogen, including novel plasmid vectors and techniques for mutagenesis, which allowed for the study of important virulence factors.
  • The study successfully inactivated a critical gene involved in glycosylation, demonstrating a powerful approach to further investigate the pathogen's virulence and potentially reduce reliance on antibiotics for disease control.
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Role of dust in Salmonella transmission on chicken farms is not well characterised. Salmonella Typhimurium (ST) infection of commercial layer chickens was investigated using a novel sprinkling method of chicken dust spiked with ST and the uptake compared to a conventional oral infection. While both inoculation methods resulted in colonisation of the intestines, the Salmonella load in liver samples was significantly higher at 7 dpi after exposing chicks to sprinkled dust compared to the oral infection group.

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Article Synopsis
  • The study investigates the effectiveness of a live attenuated vaccine (Vaxsafe ST) in reducing the shedding of harmful bacteria in layer poultry by altering gut microbiota through oral vaccination at different doses and diluents.
  • Results show that while the vaccine minimally affected overall gut microbiota diversity, significant differences in microbial community composition were observed between vaccinated and unvaccinated chickens.
  • Chicken age had a more pronounced impact on gut microbiota changes compared to the vaccine dosage or diluent, with older chicks exhibiting higher microbial diversity and changes in specific bacterial genera.
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Nanoparticles show great promise as a platform for developing vaccines for the prevention of infectious disease. We have been investigating a method whereby nanocapsules can be formulated from protein, such that the final capsules contain only the cross-linked protein itself. Such nanocapsules are made using a silica templating system and can be customised in terms of size and porosity.

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The supplementation of antimicrobial growth promoters (AGPs) has been banned in many countries because of the emergence of antimicrobial-resistant pathogens in poultry products and the environment. Probiotics have been broadly studied and demonstrated as a promising AGP substitute. Our study is centred on the effects of a multi-strain -based probiotic product on broiler production performance and gut microbial profile in a dexamethasone-induced leaky gut challenge.

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Background: The gut microbiota influences chicken health, welfare, and productivity. A diverse and balanced microbiota has been associated with improved growth, efficient feed utilisation, a well-developed immune system, disease resistance, and stress tolerance in chickens. Previous studies on chicken gut microbiota have predominantly focused on broiler chickens and have usually been limited to one or two sections of the digestive system, under controlled research environments, and often sampled at a single time point.

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This research investigates the effects of phytogenic feed additives (PFAs) on the growth performance, gut microbial community, and microbial metabolic functions in weaned piglets via a combined 16S rRNA gene amplicon and shotgun metagenomics approach. A controlled trial was conducted using 200 pigs to highlight the significant influence of PFAs on gut microbiota dynamics. Notably, the treatment group revealed an increased gut microbiota diversity, as measured with the Shannon and Simpson indices.

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Antimicrobial peptides have the potential to be used in a range of applications, including as an alternative to conventional antibiotics for the treatment of bacterial infections of humans and animals. Therefore, there is interest in identifying novel bacteriocins which have desirable physico-chemical properties or antimicrobial activities. #23, isolated from a marine sponge, has wide spectrum antimicrobial activity against Gram-negative and Gram-positive bacteria.

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The microbiota of the gastrointestinal tract influences gut health, which in turn strongly impacts the general health and productivity of laying hens. It is essential to characterise the composition and temporal development of the gut microbiota in healthy layers raised under different management systems, to understand the variations in typical healthy microbiota structure, so that deviations from this might be recognised and correlated with production and health issues when they arise. The present investigation aimed to study the temporal development and phylogenetic composition of the gut microbiota of four commercially raised layer flocks from hatch to end of the production cycle.

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Hospital-acquired diarrhoea (HAD) is common, and often associated with gut microbiota and metabolome dysbiosis following antibiotic administration. Clostridioides difficile is the most significant antibiotic-associated diarrhoeal (AAD) pathogen, but less is known about the microbiota and metabolome associated with AAD and C. difficile infection (CDI) with contrasting antibiotic treatment.

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is the aetiological agent of Spotty Liver Disease (SLD). SLD can cause significant production loss and mortalities among layer hens at and around peak of lay. We previously developed an enzyme linked immunosorbent assay (ELISA), SLD-ELISA1, to detect specific antibodies from bird sera using total proteins and sera pre-absorbed with proteins.

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Background: Bacteriophages are viral predators of bacteria and are common in nature. Their host-specific infections against specific bacteria make them an attractive natural agent to control bacterial pathogens. Interest in the potential of bacteriophages as antibacterial agents in the production animal industries has increased.

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Campylobacter hepaticus is an important pathogen which causes Spotty Liver Disease (SLD) in layer chickens. SLD results in an increase in mortality and a significant decrease in egg production and therefore is an important economic concern of the global poultry industry. The human pathogen Campylobacter jejuni encodes an N-linked glycosylation system that plays fundamental roles in host colonization and pathogenicity.

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The concept of designer microbiota in chicken is focused on early exposure of the hatchlings to pathogen-free microbiota inoculum, limiting the early access to harmful and pathogenic microorganisms, thus promoting colonisation of the gut with beneficial and natural poultry microbiota. In this study, we controlled colonisation of the intestine in broiler chickens in a large-scale industrial setting via at-hatch administration of a commercial product containing a highly diverse microbiota originating from the chicken caecum. The treatment significantly transformed the microbiota membership in the crop, proventriculus, jejunum and caecum and significantly altered the taxa abundance in the jejunum, jejunum mucosa, and caecum estimated using PERMANOVA and unweighted and weighted UniFrac distances, respectively.

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Spotty liver disease (SLD) caused by affects the health and productivity of layer hens and is a disease of concern in poultry. In this study, blood and cloacal swab samples were collected from 709 birds across 11 free-range layer farms from different regions of Australia. The prevalence of specific antibodies and DNA was assessed using a specific ELISA and PCR and its correlation with mortalities and changes in egg production was analyzed to better understand the seroprevalence of in Australian free-range layer farms.

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Spotty Liver Disease (SLD) is a significant disease of commercial layer hens. It can cause up to 10 % flock mortalities and reduce egg production by 25 %. Campylobacter hepaticus has been identified as the main cause of the disease, although it also appears that predisposing factors, such as some form of stress, may increase the likelihood of clinical disease occurring.

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Spotty liver disease (SLD) causes substantial egg production losses and chicken mortality; therefore, it is a disease that concerns Australian egg farmers. Over the last few decades, much research has been conducted to determine the etiologic agents of SLD and to develop potential therapeutics; however, SLD still remains a major issue for the chicken industries globally and remained without the elucidation of potentially multiple pathogens involved. To help fill this gap, this study was aimed at understanding the viral diversity of bile samples from which the SLD-causing bacterium, , has been isolated and characterised.

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Spotty Liver Disease (SLD) is a serious infectious disease which occurs mainly in laying chickens in free range production systems. SLD outbreaks can increase mortality and decrease egg production of chickens, adversely impact welfare and cause economic hardship for poultry producers. The bacterium is the primary cause of the disease.

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Poultry production is among the most challenging industries for pathogen control. High animal density and abundance of faecal material demand strict biosecurity measures and continual vigilance in monitoring animal health parameters. Despite this vigilance, dealing with disease outbreaks is a part of farmers' routines.

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A novel species of was isolated from bile samples of chickens with spotty liver disease in Australia, making it the second novel species isolated from chickens with the disease, after was isolated and described in 2016. Six independently derived isolates were obtained. They were Gram-stain-negative, microaerobic, catalase-positive, oxidase-positive and urease-negative.

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Campylobacter hepaticus causes Spotty Liver Disease (SLD) in layer hens, resulting in mortality and productivity losses. Like other Campylobacter species, C. hepaticus is a fastidious organism that requires microaerobic conditions to grow and efficiently replicate.

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