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Improved surveillance systems and understanding of the natural transmission cycles of Japanese encephalitis virus in remote communities of the Torres Strait and Cape York Peninsula.
Andrew van den Hurk, Ina Smith, Greg Smith, in collaboration with Sonja Hall-Mendelin, Lydia Hill (UQ), Wai Yuen Cheah (UQ) Dr. Scott Ritchie (TPHU), Professor John Mackenzie (Curtin), Dr. Nigle Beebe (Uni Technology).
This four year AHMRC funded project has entered its forth and final year and can boast a number of sucesses. Among the main findings the project demonstrated that while wild caught mosquitoes can be used to successfully identify the circulation of Japanese encephalitis virus in remote parts of northern Australia the technical difficulties and large numbers of mosquitos requireing processing has made the approach untenerable in the longer term. This has led to laboratory based studies to explore the use of sugar soaked pleaglets upon which field trapped mosquitos feed as an alternative to actual processeing of the individual mosquitos. Early laboratory based results using this alternative approach have proved encourgaing and this is the subject of a recently submitted grant application. The project was able to develop real time PCR (TaqMan) assays for the speciation of wild caught mosquitoes as well as the identification of the vertebrate host upon which they have fed.
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Mechanisms of virus transport in indoor environment.
Greg Smith, in collaboration with Bruce Harrower, Judy Northill (QHSS), Phillipa Perrott, Lidia Morawska, Megean Hargreaves, Zoran Ristosvski, (QUT) and Stephen Corbett (WSAHS).
The unit is collaborating with Researchers at the Queensland University of Technology to investigate the mechanisms of viral transport in indoor environments using influenza as a model organism. This ARC Discovery grant will allow us to investigate for the first time the impact which droplet size, humidity, temperature and other environmental and physiological factors have on the distribution of respiratory viruses in indoor environments. Work has commenced on the development of highly sensitive ‘nested’ TaqMan based assays to detect a range of respiratory viruses while an elaborate respirator chamber designed to measure droplet size and dispersal patterns of respiratory secretions following talking and coughing is nearing completion. It is hoped that the collaboration of virologists and physicists will begin to shed light on factors which affect the dispersal of viruses in indoor environments and eventually lead to improved infection control practices in respiratory wards and hospital environments.
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Assessment of black flying foxes (Pteropus alecto) as potential amplifying hosts of Japanese encephalitis virus.
Andrew van den Hurk, Ina Smith, Greg Smith, Bruce Harrower, Carmel Taylor In collaboration with Hume Field, Craig Smith, (QDPI&F); Prof John Mackenzie, Curtin University.
This AHMRC and AB CRC funded project has concluded and demonstrated that flying foxes can serve as amplifying host of Japanese Encephalitis virus. This raises the possibility that flying foxes flying between Papua New Guinea, the islands of the Torres Strait and the Northern Peninsula Area of far north Queensland could be responsible for the periodic introduction of the virus onto mainland Australia. This finding also raises the possibility that flying foxes could serve to distribute the virus more widely should it become established in far north Queensland. In addition to establishing that the flying fox could serve as an amplifying host for Japanese encephalitis virus the project has clearly demonstrated the value of using mosquitos both to transmit viruses to vertebrate hosts as well as for detecting viremia in infected animals. Although conventional virological approaches (virus isolation, TaqMan) failed to demonstrate viremia in infected flying foxes, mosquitos which fed on infected animals became infected suggesting they are a much more sensitive (and realistic) approach for investigating the transmission of arboviruses.
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Production of a non-infectious Ross river virus that can be used for diagnostic purposes and vaccine applications and to identify portions of the rrv genome that are important as determinants of virus host range and pathogenicity.
Alyssa Pyke, Greg Smith in collaboration with Roy Hall (UQ).
As part of her PhD Alyssa has shown proof-of-concept in the production of a novel trans-complemented Ross River virus which can be used for diagnostic applications without the hazard and inconvenience of chemical inactivation. The virus can be grown safely using traditional cell culture based propagation methods and then used directly in diagnostic assays without the usual requirement for chemical inactivation. The approach uses an E1 defective ‘infectious clone of Ross River Virus’ which when grown in a transgenic cell line expressing E1 results in the formation of fully intact virions which due to the EI deletion cannot replicate in non-complementing cell lines or vertebrate or invertebrate hosts. This trans-complemented infectious clone system will be further evaluated as a potential vaccine while a full-length infectious clone will be used to explore the molecular basis of virus-mosquito adaptation and evolution.
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Australian bat Lyssavirus: host susceptibility, efficacy of current vaccines and development of an ABLV vaccine-vector system.
Greg Smith, Ina Smith, Bruce Harrower, Scott Craig, Peter Moore (UQ), Janine Barrett (QDPI&F)
Work has commenced on establishing whether or not the rabies vaccine and post exposure prophylaxis regimes current used to protect against Australia bat lyssavirus (ABLV) exposure provide an adequate level of protection. This Australian Biosecurity CRC funded research will potentially have profound ramifications for the future management of Australian bat lyssavirus exposures not only in Queensland but throughout Australia. The project will characterise individual ABLV strains in vivo to identify a highly neuroinvasive and neuropathogenic strain which can be used as a challenge strain in vaccine efficacy trials planned for 2007. The project also intends to fully sequence a number of ABLV genomes to determine whether any areas of the genome can be used as a geographic or species-specific marker for individual ABLV strains.
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The application of a reverse genetics approach to determine the genetic basis between australian bat lyssavirus (ABL) isolates with widely varying neurovirulent and neuroinvasive phenotypes.
Ina Smith, Greg Smith, Scott Craig, Bruce Harrower, Peter Moore, Roy Hall (UQ) Janine Barrett (QDPI&F).
Work focusing on Australian bat lyssavirus has gained momentum as we near completion of an infectious clone system which will provided us with an unrivalled opportunity to explore the molecular basis of virulence. The genomic information and phenotypic characterisation of individual ABLV isolates undertaken as part of the rabies vaccine efficacy trial described above will be used in companion studies funded by Queensland Health to investigate the molecular basis of neuroinvasiveness. In addition an infectious clone will provide a platform for the development of a safe and effective vaccine and the development of safe, specific and sensitive diagnostic assays.
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Development of a multiplexed, luminex-based approach for the diagnosis and serological identification of acute human zoonotic and arboviral infections of public health importance to Australia.
Greg Smith, Ina Smith, in collaboration with Alyssa Pyke, Carmel Taylor, (QHSS) Vivienne Irwin and Roy Hall (UQ).
The accurate diagnosis of exotic Flaviviruses (Dengue, Japanese encephalitis, Yellow Fever) is particularly challenging in Australia due to the circulation of a large number of endemic Flavivirus (Stratford, Edge Hill, Kokabera, Kunjin, Alfuy and Murray Valley encephalitis) which produce confounding serological cross reactions. This recently commenced AB-CRC funded project aims to develop multi-anolyte, bead-based (Luminex) assays for the detection of specific serological reactivity to both exotic and endemic Flaviviruses in infected individuals. The Luminex-based approach offers the possibility of performing only one or two individual multiplex assays as opposed to 12 individual ELISA assays with a concomitant reduction in the quantity of serum required. By moving to a recombinant antigen based approach the biosafety risk and expense associated with the production of whole, inactivate viruses would be avoided and the possibility of ‘exporting’ the tests to other laboratories in other states is greatly enhanced. The approach will also be used to develop serological tests for a number of exotic viruses using totally synthetic, recombinant derived proteins.
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Molecular analysis systems for biosecurity.
Greg Smith, Ina Smith, in collaboration with Carmel Taylor, Alyssa Pyke (QHSS), Stephen Prowse (AB-CRC), Andrew Geering, (QDPI&F); Jon Uldridge (UQ).
This Queensland Smart State and AB-CRC funded project will commence shortly and will complement the AB-CRC funded ‘Luminex project’ described above. This units involvement in this multifaceted, multi-organisation project will be to evaluate different serological and molecular applications of a novel multi-anolyte assay system developed at the University of Queensland. The serological assays developed and analysed on the Luminex platform as part of the project described above will also be evaluated on the novel UQ system.
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Is Aedes scutellaris a vector of dengue in the Torres Strait?
Andrew van den Hurk, Greg Smith in collaboration with Petrina Johnson (TPHU) and Peter Moore (Q) and Scott Ritchie, (TPHU).
This AB-CRC funded project was completed this year and demonstrated that a mosquito species not believed to be in Australia until relatively recently, Aedes scutellaris is an efficient vector for Dengue viruses. The demonstration that this mosquito is a very effective vector of dengue in laboratory trials helps explain a large scale Dengue outbreak that occurred in the Torres Strait in 2004 and resulted in 300 dengue cases and two deaths – the first fatalities attributed to dengue in Australia in over 100 years. The outbreak was initially somewhat of a mystery as dengue cases were recorded on several islands which are known to be free of the traditional dengue vector Aedes aegypti. The demonstration that Aedes scutellaris can act as an efficient vector of dengue has forced a revision of the Queensland Health, Dengue management plan and significant changes to vector control procedures in the Torres Strait. These findings and resultant changes in vector control and public health interventions should reduce the severity and magnitude of future dengue outbreaks in this region.
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Studies of the potential colonisation and establishment OF Aedes albopictus as an arbovirus vector in Australia.
Andrew van den Hurk, Greg Smith, in collaboration with Ms Lydia Hill, Jay Nicholson (UQ), Scott Ritchie (TPHU), Richard Russell ICPMR, Nigel Beebe, UTS.
This AB-CRC funded project arose out of the Aedes scutellaris project described above. While undertaking collections in the Torres Strait in order to establish a laboratory colony of Aedes scutellaris for the vector competency studies a widespread infestation of Aedes albopictus was discovered in the Torres Strait. Follow up investigations revealed that ten of seventeen islands in the Torres Strait has Aedes albopictus present. This species was not believed to be present in Australia. Aedes albopictus is recognised as an efficient vector for a number of arboviruses including dengue, Japanese encephalitis and Chikungunya. This recently commenced project aims to determine the potential of the Torres Strait strain of Aedes albopictus to colonise subtropical areas of Australia. In particular its ability to breed efficiently in colder climates and compete successfully for breeding sites with indigenous mosquito species will be investigated.
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