J Meers

University of Queensland, Brisbane, Queensland, Australia

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Publications (135)191.85 Total impact

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    ABSTRACT: There is a long-standing and increasing need to understand the immune system of the koala (Phascolarctos cinereus), an iconic marsupial species that is facing many threats to its survival. Koala retrovirus (KoRV) is thought to be a contributor to this ongoing decline. KoRV infection occurs with 100% prevalence in Queensland (QLD) but has a lower prevalence in South Australia (SA) and KoRV infection is associated with neoplastic and immunosuppressive diseases in koalas. There is anecdotal evidence that the picture of population disease associated with KoRV infection differs between these two geographic areas, however the source and relevance of these differences are unknown. The aim of this project is to characterise and to explore possible reasons for these differences, whether they are host or viral factors. We are investigating host factors as contributors to disease pathogenesis by performing studies comparing the immune response in QLD KoRV infected animals with that in SA KoRV infected and also uninfected animals. We plan to further investigate host immune response to infection by sequencing the transcriptome analysis of submandibular lymph nodes from KoRV positive and negative animals. Bioinformatics techniques will be used to identify any differences in the expression of genes associated with the innate and adaptive immune response between the koala populations. It is anticipated that this information will identify factors that influence development of KoRV associated disease, information that can hopefully be used to design koala management programs and disease prevention measures.
    No preview · Conference Paper · Nov 2015
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    ABSTRACT: Oropharyngeal and cloacal swabs have been widely used for the detection of H5N1 highly pathogenic avian Influenza A virus (HPAI virus) in birds. Previous studies have shown that the feather calamus is a site of H5N1 virus replication and therefore has potential for diagnosis of avian influenza. However, studies characterizing the value of feathers for this purpose are not available, to our knowledge; herein we present a study investigating feathers for detection of H5N1 virus. Ducks and chickens were experimentally infected with H5N1 HPAI virus belonging to 1 of 3 clades (Indonesian clades 2.1.1 and 2.1.3, Vietnamese clade 1). Different types of feathers and oropharyngeal and cloacal swab samples were compared by virus isolation. In chickens, virus was detected from all sample types: oral and cloacal swabs, and immature pectorosternal, flight, and tail feathers. During clinical disease, the viral titers were higher in feathers than swabs. In ducks, the proportion of virus-positive samples was variable depending on viral strain and time from challenge; cloacal swabs and mature pectorosternal feathers were clearly inferior to oral swabs and immature pectorosternal, tail, and flight feathers. In ducks infected with Indonesian strains, in which most birds did not develop clinical signs, all sampling methods gave intermittent positive results; 3–23% of immature pectorosternal feathers were positive during the acute infection period; oropharyngeal swabs had slightly higher positivity during early infection, while feathers performed better during late infection. Our results indicate that immature feathers are an alternative sample for the diagnosis of HPAI in chickens and ducks.
    No preview · Article · Oct 2015 · Journal of veterinary diagnostic investigation: official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc
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    ABSTRACT: Highly pathogenic avian influenza (HPAI) causes significant economic loss, reduced food security and poses an ongoing pandemic threat. Poultry vaccination significantly decreases these problems and recognizes that the health of humans, animals and ecosystems are connected. Low-cost manufacture of poultry vaccine matched quickly to the ever-changing circulating strain is needed for effective vaccination. Here, we re-engineered the process to manufacture bacterially synthesized modular capsomere comprising influenza M2e, previously shown to confer complete protection in challenged mice, for application in poultry. Modular capsomere was prepared using a simplified non-chromatographic salting-out precipitation method and its immunogenicity tested in vivo in poultry. Modular capsomere crudely purified by precipitation (pCapM2e) contained more contaminants than equivalent product purified by chromatography (cCapM2e). Unadjuvanted pCapM2e containing 80EU of endotoxin per dose was inferior to highly purified and adjuvanted cCapM2e (2EU per dose). However, addition of adjuvant to pCapM2e resulting in high immunogenicity after only a single dose of vaccination, yet without any local adverse reaction. This finding suggests a strong synergy between adjuvant, antigen and contaminants, and the possible existence of a "Goldilocks" level of contaminants, where high immunogenicity and low reactogenicity can be obtained in a single-shot vaccination. The simplified process offers potential cost and speed advantages to address the needs in influenza poultry vaccination in low-cost veterinary markets.
    No preview · Article · Sep 2015 · Vaccine
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    ABSTRACT: Meleagrid herpesvirus 1 (MeHV-1) infectious bacterial artificial chromosomes (iBACs) are ideal vectors for the development of recombinant vaccines for the poultry industry. However, the full potential of iBACS as vectors can only be realised after thorough genetic characterisation, including identification of those genetic locations that are non-essential for virus replication. Generally, transposition has proven to be a highly effective strategy for rapid and efficient mutagenesis of iBAC clones. The current study describes the characterisation of 34 MeHV-1 mutants containing transposon insertions within the pMeHV1-C18 iBAC genome. Tn5 and MuA transposition methods were used to generate a library of 76 MeHV-1 insertion mutants. The capacity of each mutant to facilitate the recovery of infectious MeHV-1 was determined by the transfection of clone DNA into chicken embryo fibroblasts. Attempts to recover infectious virus from the modified clones identified 14 genetic locations that were essential for MeHV-1 replication in cell culture. Infectious MeHV-1 was recovered from the remaining 14 intragenic insertion mutants and six intergenic insertion mutants, suggesting that the respective insertion locations are non-essential for MeHV-1 replication in cell culture. The essential and non-essential designations for those MeHV-1 genes characterised in this study were generally in agreement with previous reports for other herpesviruses homologues. However, the requirement for the mardivirus-specific genes LORF4A and LORF5 are reported for the first time. These findings will help direct future work on the development of recombinant poultry vaccines using MeHV-1 as a vector by identifying potential transgene insertion sites within the viral genome.
    Full-text · Article · Aug 2015 · Virology Journal
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    ABSTRACT: Retroviral particles were first identified in tissues from a leukaemic koala in 1988. The virus was successfully isolated from Queensland (QLD) koalas and the full genome was sequenced in 2000. Koala retrovirus (KoRV) is the only known exogenous retrovirus undergoing a process of active endogenisation in its host at the present time. KoRV is 100% prevalent within QLD koalas and the virus has endogenised in that population, with high proviral (DNA) loads reported. These populations also have high levels of chlamydiosis (40%) and neoplasia. The scenario is different in South Australia (SA) where KoRV-free animals are present, and apparently both endogenous and exogenous forms of the virus exist. There is anecdotal evidence that the picture of population disease associated with KoRV infection differs between these two geographic areas however the source and relevance of these differences is unknown. The aim of this project is to characterise these differences and to explore possible reasons, whether they are host or viral factors. Viruses from both areas will be characterised, proviral and viral (RNA) load will be quantified and compared to pathology and the host response to infection will be characterised using transcriptome analysis. It is hypothesised that high viral load is associated with disease advancement because, as the viral load becomes high, the chance of insertional mutagenesis and subsequent tumour induction increases. Virus will be cultured to investigate any sequence variation between virus isolates from SA and QLD koalas. Transcriptome analysis will identify differences in expression of genes associated with the immune response between QLD and SA populations and between KoRV-infected and uninfected koalas. The transcriptome study may also provide information about characteristics of KoRV in the koala genome. It is anticipated that this information will identify factors that influence development of KoRV associated disease, information that can hopefully be used to design koala management programs and disease prevention measures.
    No preview · Conference Paper · Jul 2015
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    ABSTRACT: Meleagrid herpesvirus 1 (MeHV-1 or turkey herpesvirus) has been widely used as a vaccine in commercial poultry. Initially, these vaccine applications were for the prevention of Marek's disease resulting from Gallid herpesvirus 2 infections, while more recently MeHV-1 has been used as recombinant vector for other poultry infections. The construction of herpesvirus infectious clones that permit propagation and manipulation of the viral genome in bacterial hosts has advanced the studies of herpesviral genetics. The current study reports the construction of five MeHV-1 infectious clones. The in vitro properties of viruses recovered from these clones were indistinguishable from the parental MeHV-1. In contrast, the rescued MeHV-1 viruses were significantly attenuated when used in vivo. Complete sequencing of the infectious clones identified the absence of two regions of the MeHV-1 genome compared to the MeHV-1 reference sequence. These analyses determined the rescued viruses have seven genes, UL43, UL44, UL45, UL56, HVT071, sorf3 and US2 either partially or completely deleted. In addition, single nucleotide polymorphisms were identified in all clones compared with the MeHV-1 reference sequence. As a consequence of one of the polymorphisms identified in the UL13 gene, four of the rescued viruses were predicted to encode a serine/threonine protein kinase lacking two of three domains required for activity. Thus four of the recovered viruses have a total of eight missing or defective genes. The implications of these findings in the context of herpesvirus biology and infectious clone construction are discussed.
    No preview · Article · Jul 2015 · Virus Genes
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    ABSTRACT: This paper establishes reference ranges for hematologic and plasma biochemistry values in wild Black flying-foxes (Pteropus alecto) captured in South East Queensland, Australia. Values were found to be consistent with those of other Pteropus species. Four hundred and forty-seven animals were sampled over 12 months and significant differences were found between age, sex, reproductive and body condition cohorts in the sample population. Mean values for each cohort fell within the determined normal adult reference range, with the exception of elevated levels of alkaline phosphatase in juvenile animals. Hematologic and biochemistry parameters of injured animals showed little or no deviation from the normal reference values for minor injuries, while two animals with more severe injury or abscessation showed leucocytosis, anaemia, thrombocytosis, hyperglobulinemia and hypoalbuminemia.
    Full-text · Article · May 2015 · PLoS ONE
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    Joerg Henning · Than Hla · Joanne Meers
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    ABSTRACT: Improvement in animal disease control and prevention is dependent on several factors including farmers' uptake of new technologies and skills, particularly in developing countries. Extension is the means by which information about these technologies and skills is delivered to farmers, in order that they can use this knowledge to improve farming practices and their quality of life. This implies a shift from traditional methods to new science-based methods of production. However, in many developing countries farmers are illiterate and unable to understand written outcomes of scientific research. This paper summarizes approaches to communicate epidemiological findings and reports on experiences obtained from a research project in Myanmar, where results from epidemiological field investigations and intervention studies were 'translated' in an understandable manner to village communities. Rural chicken farmers were the central focus of this extension work and simple and sustainable methods to improve the health and production of scavenging chicken flocks were promoted. Unique extension materials transformed scientific outputs published in international journals into clear pictographic messages comprehendible by villagers, while maintaining country-specific, traditional, religious and public perspectives. Benefits, difficulties and pitfalls in using extension methods to communicate advice on preventive veterinary medicine measures in different cross-cultural settings are discussed and guidelines on how to distribute epidemiological research results to illiterate farmers are provided.
    Preview · Article · Dec 2014 · SpringerPlus
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    Greg Simmons · Daniel Clarke · Jeff McKee · Paul Young · Joanne Meers
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    ABSTRACT: Gibbon ape leukaemia virus (GALV) and koala retrovirus (KoRV) share a remarkably close sequence identity despite the fact that they occur in distantly related mammals on different continents. It has previously been suggested that infection of their respective hosts may have occurred as a result of a species jump from another, as yet unidentified vertebrate host. To investigate possible sources of these retroviruses in the Australian context, DNA samples were obtained from 42 vertebrate species and screened using PCR in order to detect proviral sequences closely related to KoRV and GALV. Four proviral partial sequences totalling 2880 bases which share a strong similarity with KoRV and GALV were detected in DNA from a native Australian rodent, the grassland melomys, Melomys burtoni. We have designated this novel gammaretrovirus Melomys burtoni retrovirus (MbRV). The concatenated nucleotide sequence of MbRV shares 93% identity with the corresponding sequence from GALV-SEATO and 83% identity with KoRV. The geographic ranges of the grassland melomys and of the koala partially overlap. Thus a species jump by MbRV from melomys to koalas is conceivable. However the genus Melomys does not occur in mainland South East Asia and so it appears most likely that another as yet unidentified host was the source of GALV.
    Preview · Article · Sep 2014 · PLoS ONE
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    ABSTRACT: Veterinarians have few tools to predict the rate of disease progression in FIV-infected cats. In contrast, in HIV infection plasma viral RNA load and acute phase protein concentrations are commonly used as predictors of disease progression. This study evaluated these predictors in cats naturally infected with FIV. In older cats (> 5 years), log10 FIV RNA load was higher in the terminal stages of disease compared to the asymptomatic stage. There was a significant association between log10 FIV RNA load and both log10 serum amyloid A concentration and age in unwell FIV-infected cats. This study suggests that viral RNA load and serum amyloid A warrant further investigation as predictors of disease status and prognosis in FIV-infected cats.
    No preview · Article · Aug 2014 · The Veterinary Journal

  • No preview · Article · May 2014

  • No preview · Article · May 2014
  • S E Roche · S Costard · J Meers · H E Field · A C Breed
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    ABSTRACT: Nipah virus (NiV) is a recently emerged zoonotic virus that causes severe disease in humans. The reservoir hosts for NiV, bats of the genus Pteropus (known as flying-foxes) are found across the Asia-Pacific including Australia. While NiV has not been detected in Australia, evidence for NiV infection has been found in flying-foxes in some of Australia's closest neighbours. A qualitative risk assessment was undertaken to assess the risk of NiV establishing in Australian flying-foxes through flying-fox movements from nearby regions. Events surrounding the emergence of new diseases are typically uncertain and in this study an expert opinion workshop was used to address gaps in knowledge. Given the difficulties in combining expert opinion, five different combination methods were analysed to assess their influence on the risk outcome. Under the baseline scenario where the median was used to combine opinions, the risk was estimated to be very low. However, this risk increased when the mean and linear opinion pooling combination methods were used. This assessment highlights the effects that different methods for combining expert opinion have on final risk estimates and the caution needed when interpreting these outcomes given the high degree of uncertainty in expert opinion. This work has provided a flexible model framework for assessing the risk of NiV establishment in Australian flying-foxes through bat movements which can be updated when new data become available.
    No preview · Article · Feb 2014 · Epidemiology and Infection
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    ABSTRACT: Ducks are important maintenance hosts for avian influenza, including H5N1 highly pathogenic avian influenza viruses. A previous study indicated that persistence of H5N1 viruses in ducks after the development of humoral immunity may drive viral evolution following immune selection. As H5N1 HPAI is endemic in Indonesia, this mechanism may be important in understanding H5N1 evolution in that region. To determine the capability of domestic ducks to maintain prolonged shedding of Indonesian clade 2.1 H5N1 virus, two groups of Pekin ducks were inoculated through the eyes, nostrils and oropharynx and viral shedding and transmission investigated. Inoculated ducks (n = 15), which were mostly asymptomatic, shed infectious virus from the oral route from 1 to 8 days post inoculation, and from the cloacal route from 2-8 dpi. Viral ribonucleic acid was detected from 1-15 days post inoculation from the oral route and 1-24 days post inoculation from the cloacal route (cycle threshold <40). Most ducks seroconverted in a range of serological tests by 15 days post inoculation. Virus was efficiently transmitted during acute infection (5 inoculation-infected to all 5 contact ducks). However, no evidence for transmission, as determined by seroconversion and viral shedding, was found between an inoculation-infected group (n = 10) and contact ducks (n = 9) when the two groups only had contact after 10 days post inoculation. Clinical disease was more frequent and more severe in contact-infected (2 of 5) than inoculation-infected ducks (1 of 15). We conclude that Indonesian clade 2.1 H5N1 highly pathogenic avian influenza virus does not persist in individual ducks after acute infection.
    Full-text · Article · Jan 2014 · PLoS ONE
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    ABSTRACT: Ducks are important maintenance hosts for avian influenza, including H5N1 highly pathogenic avian influenza viruses. A previous study indicated that persistence of H5N1 viruses in ducks after the development of humoral immunity may drive viral evolution following immune selection. As H5N1 HPAI is endemic in Indonesia, this mechanism may be important in understanding H5N1 evolution in that region. To determine the capability of domestic ducks to maintain prolonged shedding of Indonesian clade 2.1 H5N1 virus, two groups of Pekin ducks were inoculated through the eyes, nostrils and oropharynx and viral shedding and transmission investigated. Inoculated ducks (n = 15), which were mostly asymptomatic, shed infectious virus from the oral route from 1 to 8 days post inoculation, and from the cloacal route from 2-8 dpi. Viral ribonucleic acid was detected from 1-15 days post inoculation from the oral route and 1-24 days post inoculation from the cloacal route (cycle threshold <40). Most ducks seroconverted in a range of serological tests by 15 days post inoculation. Virus was efficiently transmitted during acute infection (5 inoculation-infected to all 5 contact ducks). However, no evidence for transmission, as determined by seroconversion and viral shedding, was found between an inoculation-infected group (n = 10) and contact ducks (n = 9) when the two groups only had contact after 10 days post inoculation. Clinical disease was more frequent and more severe in contact-infected (2 of 5) than inoculation-infected ducks (1 of 15). We conclude that Indonesian clade 2.1 H5N1 highly pathogenic avian influenza virus does not persist in individual ducks after acute infection.
    Full-text · Article · Jan 2014 · PLoS ONE
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    ABSTRACT: The propagation of herpesvirus genomes as infectious bacterial artificial chromosomes (iBAC) has enabled the application of highly efficient strategies to investigate gene function across the genome. One of these strategies, transposition, has been used successfully on a number of herpesvirus iBACs to generate libraries of gene disruption mutants. Gene deletion studies aimed at determining the dispensable gene repertoire of the Meleagrid herpesvirus 1 (MeHV-1) genome to enhance the utility of this virus as a vaccine vector have been conducted in this report. A MeHV-1 iBAC was used in combination with the Tn5 and MuA transposition systems in an attempt to generate MeHV-1 gene interruption libraries. However, these studies demonstrated that Tn5 transposition events into the MeHV-1 genome occurred at unexpectedly low frequencies. Furthermore, characterization of genomic locations of the rare Tn5 transposon insertion events indicated a nonrandom distribution within the viral genome, with seven of the 24 insertions occurring within the gene encoding infected cell protein 4. Although insertion events with the MuA system occurred at higher frequency compared with the Tn5 system, fewer insertion events were generated than has previously been reported with this system. The characterization and distribution of these MeHV-1 iBAC transposed mutants is discussed at both the nucleotide and genomic level, and the properties of the MeHV-1 genome that could influence transposition frequency are discussed.
    No preview · Article · Jun 2013 · Avian Diseases
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    ABSTRACT: Nipah virus (NiV) (Genus Henipavirus) is a recently emerged zoonotic virus that causes severe disease in humans and has been found in bats of the genus Pteropus. Whilst NiV has not been detected in Australia, evidence for NiV-infection has been found in pteropid bats in some of Australia's closest neighbours. The aim of this study was to determine the occurrence of henipaviruses in fruit bat (Family Pteropodidae) populations to the north of Australia. In particular we tested the hypothesis that Nipah virus is restricted to west of Wallace's Line. Fruit bats from Australia, Papua New Guinea, East Timor and Indonesia were tested for the presence of antibodies to Hendra virus (HeV) and Nipah virus, and tested for the presence of HeV, NiV or henipavirus RNA by PCR. Evidence was found for the presence of Nipah virus in both Pteropus vampyrus and Rousettus amplexicaudatus populations from East Timor. Serology and PCR also suggested the presence of a henipavirus that was neither HeV nor NiV in Pteropus alecto and Acerodon celebensis. The results demonstrate the presence of NiV in the fruit bat populations on the eastern side of Wallace's Line and within 500 km of Australia. They indicate the presence of non-NiV, non-HeV henipaviruses in fruit bat populations of Sulawesi and Sumba and possibly in Papua New Guinea. It appears that NiV is present where P. vampyrus occurs, such as in the fruit bat populations of Timor, but where this bat species is absent other henipaviruses may be present, as on Sulawesi and Sumba. Evidence was obtained for the presence henipaviruses in the non-Pteropid species R. amplexicaudatus and in A. celebensis. The findings of this work fill some gaps in knowledge in geographical and species distribution of henipaviruses in Australasia which will contribute to planning of risk management and surveillance activities.
    Full-text · Article · Apr 2013 · PLoS ONE
  • J Henning · J Morton · R Pym · T Hla · K Sunn · J Meers
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    ABSTRACT: A cost-benefit analysis using deterministic and stochastic modelling was conducted to identify the net benefits for households that adopt (1) vaccination of individual birds against Newcastle disease (ND) or (2) improved management of chick rearing by providing coops for the protection of chicks from predation and chick starter feed inside a creep feeder to support chicks' nutrition in village chicken flocks in Myanmar. Partial budgeting was used to assess the additional costs and benefits associated with each of the two interventions tested relative to neither strategy. In the deterministic model, over the first 3 years after the introduction of the interventions, the cumulative sum of the net differences from neither strategy was 13,189Kyat for ND vaccination and 77,645Kyat for improved chick management (effective exchange rate in 2005: 1000Kyat=1$US). Both interventions were also profitable after discounting over a 10-year period; Net Present Values for ND vaccination and improved chick management were 30,791 and 167,825Kyat, respectively. The Benefit-Cost Ratio for ND vaccination was very high (28.8). This was lower for improved chick management, due to greater costs of the intervention, but still favourable at 4.7. Using both interventions concurrently yielded a Net Present Value of 470,543Kyat and a Benefit-Cost Ratio of 11.2 over the 10-year period in the deterministic model. Using the stochastic model, for the first 3 years following the introduction of the interventions, the mean cumulative sums of the net difference were similar to those values obtained from the deterministic model. Sensitivity analysis indicated that the cumulative net differences were strongly influenced by grower bird sale income, particularly under improved chick management. The effects of the strategies on odds of households selling and consuming birds after 7 months, and numbers of birds being sold or consumed after this period also influenced profitability. Cost variations for equipment used under improved chick management were not markedly associated with profitability. Net Present Values and Benefit-Cost Ratios discounted over a 10-year period were also similar to the deterministic model when mean values obtained through stochastic modelling were used. In summary, the study showed that ND vaccination and improved chick management can improve the viability and profitability of village chicken production in Myanmar.
    No preview · Article · Feb 2013 · Preventive Veterinary Medicine
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    ABSTRACT: To determine the pathobiology of Indonesian H5N1 highly pathogenic avian influenza, two viruses representing clades 2.1.1 and 2.1.3 were inoculated into broiler chickens and Pekin ducks via the eyes, nostrils and oropharynx. In chickens, both viruses produced fulminant disease; tissue tropism was broad but predominantly endothelial and viral loads in tissues were high. Except for one case of meningoencephalitis, the infection in ducks was sub-clinical, leading only to seroconversion. In these ducks, virus and viral antigen occurred in lower amounts, mainly in the respiratory tract (airsac and sinuses), prior to day 7 after inoculation. During clinical disease, chickens shed high virus titres orally and cloacally. Ducks intermittently shed low virus titres from the oral route for up to 8 days post-inoculation. We discuss the significance of the data for understanding the pathogenesis and pathobiology of Indonesian H5N1 in chickens and ducks.
    Full-text · Article · Jan 2013 · Comparative immunology, microbiology and infectious diseases

  • No preview · Article · Dec 2012

Publication Stats

1k Citations
191.85 Total Impact Points

Institutions

  • 2002-2015
    • University of Queensland
      • School of Veterinary Science
      Brisbane, Queensland, Australia
  • 2009
    • SciQuest
      North Carolina, United States
  • 1997-2002
    • Massey University
      • Institute of Veterinary, Animal and Biomedical Sciences
      Palmerston North, Manawatu-Wanganui, New Zealand