Research, Innovation and Commercialisation - Research Publications
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ItemAnionic Phospholipid Interactions of the Prion Protein N Terminus Are Minimally Perturbing and Not Driven Solely by the Octapeptide Repeat Domain(AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 2010-10-15)Although the N terminus of the prion protein (PrP(C)) has been shown to directly associate with lipid membranes, the precise determinants, biophysical basis, and functional implications of such binding, particularly in relation to endogenously occurring fragments, are unresolved. To better understand these issues, we studied a range of synthetic peptides: specifically those equating to the N1 (residues 23-110) and N2 (23-89) fragments derived from constitutive processing of PrP(C) and including those representing arbitrarily defined component domains of the N terminus of mouse prion protein. Utilizing more physiologically relevant large unilamellar vesicles, fluorescence studies at synaptosomal pH (7.4) showed absent binding of all peptides to lipids containing the zwitterionic headgroup phosphatidylcholine and mixtures containing the anionic headgroups phosphatidylglycerol or phosphatidylserine. At pH 5, typical of early endosomes, quartz crystal microbalance with dissipation showed the highest affinity binding occurred with N1 and N2, selective for anionic lipid species. Of particular note, the absence of binding by individual peptides representing component domains underscored the importance of the combination of the octapeptide repeat and the N-terminal polybasic regions for effective membrane interaction. In addition, using quartz crystal microbalance with dissipation and solid-state NMR, we characterized for the first time that both N1 and N2 deeply insert into the lipid bilayer with minimal disruption. Potential functional implications related to cellular stress responses are discussed.
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ItemRecombinant influenza virus expressing HIV-1 p24 capsid protein induces mucosal HIV-specific CD8 T-cell responses(ELSEVIER SCI LTD, 2016-02-24)Influenza viruses are promising mucosal vaccine vectors for HIV but their use has been limited by difficulties in engineering the expression of large amounts of foreign protein. We developed recombinant influenza viruses incorporating the HIV-1 p24 gag capsid into the NS-segment of PR8 (H1N1) and X31 (H3N2) influenza viruses with the use of multiple 2A ribosomal skip sequences. Despite the insertion of a sizable HIV-1 gene into the influenza genome, recombinant viruses were readily rescued to high titers. Intracellular expression of p24 capsid was confirmed by in vitro infection assays. The recombinant influenza viruses were subsequently tested as mucosal vaccines in BALB/c mice. Recombinant viruses were attenuated and safe in immunized mice. Systemic and mucosal HIV-specific CD8 T-cell responses were elicited in mice that were immunized via intranasal route with a prime-boost regimen. Isolated HIV-specific CD8 T-cells displayed polyfunctional cytokine and degranulation profiles. Mice boosted via intravaginal route induced recall responses from the distal lung mucosa and developed heightened HIV-specific CD8 T-cell responses in the vaginal mucosa. These findings demonstrate the potential utility of recombinant influenza viruses as vaccines for mucosal immunity against HIV-1 infection.
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ItemProteomic analysis reveals novel proteins associated with the Plasmodium protein exporter PTEX and a loss of complex stability upon truncation of the core PTEX component, PTEX150(WILEY-HINDAWI, 2016-11)The Plasmodium translocon for exported proteins (PTEX) has been established as the machinery responsible for the translocation of all classes of exported proteins beyond the parasitophorous vacuolar membrane of the intraerythrocytic malaria parasite. Protein export, particularly in the asexual blood stage, is crucial for parasite survival as exported proteins are involved in remodelling the host cell, an essential process for nutrient uptake, waste removal and immune evasion. Here, we have truncated the conserved C-terminus of one of the essential PTEX components, PTEX150, in Plasmodium falciparum in an attempt to create mutants of reduced functionality. Parasites tolerated C-terminal truncations of up to 125 amino acids with no reduction in growth, protein export or the establishment of new permeability pathways. Quantitative proteomic approaches however revealed a decrease in other PTEX subunits associating with PTEX150 in truncation mutants, suggesting a role for the C-terminus of PTEX150 in regulating PTEX stability. Our analyses also reveal three previously unreported PTEX-associated proteins, namely PV1, Pf113 and Hsp70-x (respective PlasmoDB numbers; PF3D7_1129100, PF3D7_1420700 and PF3D7_0831700) and demonstrate that core PTEX proteins exist in various distinct multimeric forms outside the major complex.
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ItemMale Mating Success and the Effect of Mating History on Ejaculate Traits in a Facultatively Parthenogenic Insect (Extatosoma tiaratum)(WILEY, 2016-07)Abstract Males can typically increase their lifetime reproductive success by mating with multiple females. However, recent studies across a broad range of species have demonstrated physiological constraints on male multiple mating. In this study, we investigate male mating capacity in Extatosoma tiaratum, a facultative parthenogenetic phasmatid. Sperm limitation is thought to be one factor favouring the evolution and maintenance of parthenogenetic reproduction, but studies on male mating ability in facultative parthenogenetic species are extremely rare. To explore whether male mating success varies with mating history, we provided males with weekly mating opportunities with different females throughout their lives. We then observed mating success, and the variation in ejaculate size and quality within each mating. We showed that most, but not all, males can mate multiply, however the amount of ejaculate produced is variable and depends upon male body mass and mating history.
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ItemAdvanced glycation end products (AGEs) are cross-sectionally associated with insulin secretion in healthy subjects(SPRINGER WIEN, 2014-02)It has been postulated that chronic exposure to high levels of advanced glycation end products (AGEs), in particular from dietary sources, can impair insulin secretion. In the present study, we investigated the cross-sectional relationship between AGEs and acute insulin secretion during an intravenous glucose tolerance test (IVGTT) and following a 75 g oral glucose tolerance test (OGTT) in healthy humans. We report the cross-sectional association between circulating AGE concentrations and insulin secretory function in healthy humans (17 F: 27 M, aged 30 ± 10 years) with a wide range of BMI (24.6-31.0 kg/m(2)). Higher circulating concentrations of AGEs were related to increased first phase insulin secretion during IVGTT (r = 0.43; p < 0.05) and lower 2-h glucose concentrations during OGTT (r = -0.31; p < 0.05). In addition, fasting (r = -0.36; p < 0.05) and 2-h glucose concentrations were negatively related to circulating levels of soluble receptor for AGE (RAGE) isoforms (r = -0.39; p < 0.01). In conclusion, in healthy humans, we show a cross-sectional association between advanced glycation end products and acute insulin secretion during glucose tolerance testing.
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ItemSequential Induction of Effector Function, Tissue Migration and Cell Death during Polyclonal Activation of Mouse Regulatory T-Cells(PUBLIC LIBRARY SCIENCE, 2012-11-30)The ability of CD4(+)Foxp3(+) regulatory T-cells (Treg) to produce interleukin (IL)-10 is important for the limitation of inflammation at environmental interfaces like colon or lung. Under steady state conditions, however, few Tregs produce IL-10 ex vivo. To investigate the origin and fate of IL-10 producing Tregs we used a superagonistic mouse anti-mouse CD28 mAb (CD28SA) for polyclonal in vivo stimulation of Tregs, which not only led to their numeric expansion but also to a dramatic increase in IL-10 production. IL-10 secreting Tregs strongly upregulated surface receptors associated with suppressive function as compared to non-producing Tregs. Furthermore, polyclonally expanding Tregs shifted their migration receptor pattern after activation from a CCR7(+)CCR5(-) lymph node-seeking to a CCR7(-)CCR5(+) inflammation-seeking phenotype, explaining the preferential recruitment of IL-10 producers to sites of ongoing immune responses. Finally, we observed that IL-10 producing Tregs from CD28SA stimulated mice were more apoptosis-prone in vitro than their IL-10 negative counterparts. These findings support a model where prolonged activation of Tregs results in terminal differentiation towards an IL-10 producing effector phenotype associated with a limited lifespan, implicating built-in termination of immunosuppression.
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ItemPatents Associated with High-Cost Drugs in Australia(PUBLIC LIBRARY SCIENCE, 2013-04-05)Australia, like most countries, faces high and rapidly-rising drug costs. There are longstanding concerns about pharmaceutical companies inappropriately extending their monopoly position by "evergreening" blockbuster drugs, through misuse of the patent system. There is, however, very little empirical information about this behaviour. We fill the gap by analysing all of the patents associated with 15 of the costliest drugs in Australia over the last 20 years. Specifically, we search the patent register to identify all the granted patents that cover the active pharmaceutical ingredient of the high-cost drugs. Then, we classify the patents by type, and identify their owners. We find a mean of 49 patents associated with each drug. Three-quarters of these patents are owned by companies other than the drug's originator. Surprisingly, the majority of all patents are owned by companies that do not have a record of developing top-selling drugs. Our findings show that a multitude of players seek monopoly control over innovations to blockbuster drugs. Consequently, attempts to control drug costs by mitigating misuse of the patent system are likely to miss the mark if they focus only on the patenting activities of originators.
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ItemBiosecurity interceptions of an invasive lizard: origin of stowaways and human-assisted spread within New Zealand(WILEY, 2013-02)Globalization, and the resultant movement of animals beyond their native range, creates challenges for biosecurity agencies. Limited records of unintentional introductions inhibit our understanding of the trade pathways, transport vectors and mechanisms through which hitchhiker organisms are spread as stowaways. Here, we adopt a phylogeographic approach to determine the source and human-mediated dispersal pathways of New Zealand's only invasive lizard, the delicate skink (Lampropholis delicata), intercepted by biosecurity agencies in New Zealand. Biosecurity agencies correctly predicted the source region of 77% of stowaways, which were usually solitary adults, arriving via air or sea pathways during the cooler months, evading initial border checks and alive when detected. New arrivals from Australia comprised 16% of detections originating from the region between Brisbane and Sydney. Our analyses indicate human-mediated dispersal has driven the post-border spread of L. delicata within New Zealand. Propagule pressure was substantially greater for L. delicata compared with the noninvasive, congeneric Lampropholis guichenoti. Our results highlight the transport pathways, spread mechanisms, and stowaway characteristics of Lampropholis lizards entering New Zealand, which could enhance current biosecurity protocols and prevent the establishment of additional lizard species.
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ItemA clustered randomised trial examining the effect of social marketing and community mobilisation on the age of uptake and levels of alcohol consumption by Australian adolescents(BMJ PUBLISHING GROUP, 2013)INTRODUCTION: Throughout the world, alcohol consumption is common among adolescents. Adolescent alcohol use and misuse have prognostic significance for several adverse long-term outcomes, including alcohol problems, alcohol dependence, school disengagement and illicit drug use. The aim of this study was to evaluate whether randomisation to a community mobilisation and social marketing intervention reduces the proportion of adolescents who initiate alcohol use before the Australian legal age of 18, and the frequency and amount of underage adolescent alcohol consumption. METHOD AND ANALYSIS: The study comprises 14 communities matched with 14 non-contiguous communities on socioeconomic status (SES), location and size. One of each pair was randomly allocated to the intervention. Baseline levels of adolescent alcohol use were estimated through school surveys initiated in 2006 (N=8500). Community mobilisation and social marketing interventions were initiated in 2011 to reduce underage alcohol supply and demand. The setting is communities in three Australian states (Victoria, Queensland and Western Australia). Students (N=2576) will complete school surveys in year 8 in 2013 (average age 12). PRIMARY OUTCOMES: (1) lifetime initiation and (2) monthly frequency of alcohol use. Reports of social marketing and family and community alcohol supply sources will also be assessed. Point estimates with 95% CIs will be compared for student alcohol use in intervention and control communities. Changes from 2006 to 2013 will be examined; multilevel modelling will assess whether random assignment of communities to the intervention reduced 2013 alcohol use, after accounting for community level differences. Analyses will also assess whether exposure to social marketing activities increased the intervention target of reducing alcohol supply by parents and community members. TRIAL REGISTRATION: ACTRN12612000384853.
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ItemGenome-Wide Association Scan Identifies a Risk Locus for Preeclampsia on 2q14, Near the Inhibin, Beta B Gene(PUBLIC LIBRARY SCIENCE, 2012-03-14)Elucidating the genetic architecture of preeclampsia is a major goal in obstetric medicine. We have performed a genome-wide association study (GWAS) for preeclampsia in unrelated Australian individuals of Caucasian ancestry using the Illumina OmniExpress-12 BeadChip to successfully genotype 648,175 SNPs in 538 preeclampsia cases and 540 normal pregnancy controls. Two SNP associations (rs7579169, p = 3.58×10(-7), OR = 1.57; rs12711941, p = 4.26×10(-7), OR = 1.56) satisfied our genome-wide significance threshold (modified Bonferroni p<5.11×10(-7)). These SNPs reside in an intergenic region less than 15 kb downstream from the 3' terminus of the Inhibin, beta B (INHBB) gene on 2q14.2. They are in linkage disequilibrium (LD) with each other (r(2) = 0.92), but not (r(2)<0.80) with any other genotyped SNP ±250 kb. DNA re-sequencing in and around the INHBB structural gene identified an additional 25 variants. Of the 21 variants that we successfully genotyped back in the case-control cohort the most significant association observed was for a third intergenic SNP (rs7576192, p = 1.48×10(-7), OR = 1.59) in strong LD with the two significant GWAS SNPs (r(2)>0.92). We attempted to provide evidence of a putative regulatory role for these SNPs using bioinformatic analyses and found that they all reside within regions of low sequence conservation and/or low complexity, suggesting functional importance is low. We also explored the mRNA expression in decidua of genes ±500 kb of INHBB and found a nominally significant correlation between a transcript encoded by the EPB41L5 gene, ∼250 kb centromeric to INHBB, and preeclampsia (p = 0.03). We were unable to replicate the associations shown by the significant GWAS SNPs in case-control cohorts from Norway and Finland, leading us to conclude that it is more likely that these SNPs are in LD with as yet unidentified causal variant(s).