The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform
Peter Timms - One of the best experts on this subject based on the ideXlab platform.
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Koala immunology and infectious Diseases: How much can the koala bear?
Developmental and comparative immunology, 2018Co-Authors: Danielle Madden, Peter Timms, Alessandra D. Whaite, Elizabeth A. Jones, Katherine Belov, Adam PolkinghorneAbstract:Infectious Diseases are contributing to the decline of the iconic Australian marsupial, the koala (Phascolarctos cinereus). Infections with the obligate intracellular bacteria, Chlamydia pecorum, cause debilitating ocular and Urogenital-Tract Disease while the koala-retrovirus (KoRV) has been implicated in host immunosuppression and exacerbation of chlamydial pathogenesis. Although histological studies have provided insight into the basic architecture of koala immune tissues, our understanding of the koala immune response to infectious Disease has been limited, until recently, by a lack of species-specific immune reagents. Recent advances in the characterisation of key immune genes have focused on advancing our understanding of the immune response to Chlamydia infection, revealing commonalities in Disease pathologies and immunity between koalas and other hosts and paving the way for the development of a koala Chlamydia vaccine. This review summarises these recent findings and highlights key aspects of the koala immune system requiring further attention with particular regard to their most prominent infectious Diseases.
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Epidemiology of chlamydial infection and Disease in a free-ranging koala (Phascolarctos cinereus) population
PloS one, 2017Co-Authors: Sharon Nyari, Adam Polkinghorne, Courtney A. Waugh, Jianbao Dong, Bonnie L. Quigley, J. Hanger, Joanne Loader, Peter TimmsAbstract:Chlamydial Disease continues to be one of the main factors threatening the long-term survival of the koala (Phascolarctos cinereus). Despite this, large epidemiological studies of chlamydial infection and Disease in wild koala populations are lacking. A better understanding of the prevalence, transmission and pathogenesis is needed to improve control measures, such as the development of vaccines. We investigated the prevalence of Chlamydia pecorum infection and Disease in 160 koalas in a peri-urban wild population in Queensland, Australia and found that 31% of koalas were Chlamydia PCR positive and 28% had clinically detectable chlamydial Disease. Most infections were at the Urogenital site (27%; both males and females) with only 14% at the ocular site. Interestingly, we found that 27% (4/15) of koalas considered to be sexually immature (9–13 months) were already infected with C. pecorum, suggesting that a significant percentage of animals are infected directly from their mother. Ocular infection levels were less prevalent with increasing age (8% in koalas older than 4 years), whereas the prevalence of Urogenital Tract infections remained high into older age (26% in koalas older than 4 years), suggesting that, after mother-to-young transmission, C. pecorum is predominantly a sexually transmitted infection. While 28% of koalas in this population had clinically detectable chlamydial Disease (primarily Urogenital Tract Disease), many PCR positive koalas had no detectable Disease and importantly, not all Diseased animals were PCR positive. We also observed higher chlamydial loads in koalas who were C. pecorum infected without clinical Disease than in koalas who were C. pecorum infected with clinical Disease. These results shed light on the potential mechanisms of transmission of C. pecorum in koalas and also guide future control measures, such as vaccination.
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PREVALENCE AND PATHOLOGIC FEATURES OF CHLAMYDIA PECORUM INFECTIONS IN SOUTH AUSTRALIAN KOALAS (PHASCOLARCTOS CINEREUS)
Journal of wildlife diseases, 2016Co-Authors: K. Natasha Speight, Peter Timms, Adam Polkinghorne, Rachel Penn, Wayne Boardman, Tamieka A. Fraser, Kathryn Johnson, Rachel Faull, Sarah Bate, Lucy WoolfordAbstract:Chlamydia pecorum infection is highly prevalent in many koala ( Phascolarctos cinereus ) populations in the eastern states of Australia, causing ocular and Urogenital Tract Disease. In contrast, the current prevalence of chlamydiosis in South Australian (SA) koalas is largely unknown, with few reports of clinical cases. We examined 65 SA rescued wild koalas at necropsy and collected ocular and Urogenital swabs for the detection of C. pecorum by PCR. We detected C. pecorum in ocular or Urogenital swabs from 57 koalas (88%), and 34 koalas were positive at both ocular and Urogenital sites. Clinically overt chlamydial Disease was present in only 12 (21%) positive koalas. Gross lesions were often externally inapparent as they affected the Urogenital Tract (n=5), and 24 infected koalas had microscopically evident lesions only. Lesions were predominantly mild and included conjunctivitis, cystitis, and urethritis. Reproductive Tract Disease was infrequently observed. We detected C. pecorum in 16 (28%) koalas with no evidence of chlamydial Disease, suggesting the presence of subclinical carriers in this population. Based on these findings, chlamydiosis has a higher occurrence in SA koala populations than previously thought, but is most often mild and does not always result in overt clinical Disease; inapparent and subclinical infections appear common. Further studies of the prevalence in wild-caught SA koalas are needed along with research into the host and bacterial factors that may influence Disease outcome in these animals.
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using quantitative polymerase chain reaction to correlate chlamydia pecorum infectious load with ocular urinary and reproductive Tract Disease in the koala phascolarctos cinereus
Australian Veterinary Journal, 2011Co-Authors: Charles Wan, Jon Hanger, Jo Loader, Kenneth W Beagley, Peter Timms, Adam PolkinghorneAbstract:Complex interactions between Chlamydia pecorum infection, the immune response and Disease exist in the koala. We used quantitative polymerase chain reaction to investigate the relationship between C. pecorum infectious load and ocular and Urogenital Tract Disease. Chlamydia pecorum shedding was generally higher in animals with chronic, active Disease than in animals with inactive Disease. The absence of ocular Disease was generally associated with low levels of shedding, but relatively high levels of shedding in the Urogenital Tract were detected in some koalas without clinical Disease signs. These results suggest a complex Disease pathogenesis and clinical course in C. pecorum-infected koalas.
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Characterization of the koala biovar of Chlamydia pneumoniae at four gene loci--ompAVD4, ompB, 16S rRNA, groESL spacer region.
Systematic and applied microbiology, 1999Co-Authors: Stacey Wardrop, Anthony Fowler, Paul O'callaghan, Phillip Giffard, Peter TimmsAbstract:Koalas are infected with two species of Chlamydia, C. pecorum and C. pneumoniae. While it is known that significant generic diversity occurs in the C. pecorum strains infecting koalas, very little is known about the C. pneumoniae strains that infect this host. In the current study, 10 isolates of koala C. pneumoniae were analysed at four gene loci and found to be different to both the human and horse C. pneumoniae strains at all loci (biovar differences ranging from 0.3% at groESL up to 9.0% at ompAVD4). All koala biovar isolates studied were found to be 100% identical at ompAVD4 (all 10 isolates) and at ompB (all three isolates) genes. This lack of allelic polymorphisms at ompAVD4 has now been observed for koala C. pneumoniae, human C. pneumoniae, guinea pig inclusion conjuctivitis C. psittaci and feline conjuctivitis C. psittaci and may be correlated to a lack of antibody response to the chlamydial major outer membrane protein (MOMP) in these same strain/host combinations. This study also provides the first documented case of natural C. pneumoniae infection causing a severe and extended respiratory episode in a caprice koala population. This captive episode is in contrast to most free-range observations in which koala C. pneumoniae is rarely documented as causing respiratory, ocular or Urogenital Tract Disease.
Mary B Brown - One of the best experts on this subject based on the ideXlab platform.
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different inflammatory responses are associated with ureaplasma parvum induced uti and urolith formation
BMC Infectious Diseases, 2009Co-Authors: Leticia Reyes, Mary K Reinhard, Mary B BrownAbstract:Background Epidemiologic studies show a strong association between Ureaplasmas and Urogenital Tract Disease in humans. Since healthy humans can be colonized with Ureaplasmas, its role as a pathogen remains controversial. In order to begin to define the role of the host in Disease, we developed a rodent model of urinary Tract infection (UTI) using Fischer 344 (F344) rats. Animals were inoculated with sterile broth, 101, 103, 105, 107, or 109 log CFU of a rat-adapted strain of Ureaplasma parvum.
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Different inflammatory responses are associated with Ureaplasma parvum-induced UTI and urolith formation
BMC Infectious Diseases, 2009Co-Authors: Leticia Reyes, Mary Reinhard, Mary B BrownAbstract:Background Epidemiologic studies show a strong association between Ureaplasmas and Urogenital Tract Disease in humans. Since healthy humans can be colonized with Ureaplasmas , its role as a pathogen remains controversial. In order to begin to define the role of the host in Disease, we developed a rodent model of urinary Tract infection (UTI) using Fischer 344 (F344) rats. Animals were inoculated with sterile broth, 10^1, 10^3, 10^5, 10^7, or 10^9 log CFU of a rat-adapted strain of Ureaplasma parvum . Results Infected animals exhibited two distinct profiles, asymptomatic UTI and UTI complicated with struvite urolithiasis. Inoculum dose of U. parvum affected the incidence of UTI, and 50% to 57% of animals inoculated with ≥ 10^7 CFU of U. parvum remained infected (p < 0.04). However, inoculum dose did not influence immune response to U. parvum . Asymptomatic UTI was characterized by a minimal immune response that was predominantly monocytic and lymphocytic, with limited lesions, and elevated urinary levels of IFN-γ, IL-18 and MCP-1 (P ≤ 0.02). UTI complicated with struvite formation was characterized by an exaggerated immune response that was mostly neutrophilic (P ≤ 0.0001), with lesions that showed extensive uroepithelial hyperplasia (P ≤ 0.0001), and a predominance of IL-1α, IL-1β, and GRO/KC in the urine (P ≤ 0.02). Animals with asymptomatic UTI also had a significantly high rate of kidney infection (P ≤ 0.0005). Conclusion Complications associated with U. parvum infection are primarily dependent upon host-specific factors rather than Ureaplasma microbial load. The immune response in F344 rats is similar to that which occurs in humans with ureaplasmal associated Disease. Therefore, this model of infection is a useful tool for elucidating U. parvum -host interactions that confer UTI and Disease.
Adam Polkinghorne - One of the best experts on this subject based on the ideXlab platform.
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Koala immunology and infectious Diseases: How much can the koala bear?
Developmental and comparative immunology, 2018Co-Authors: Danielle Madden, Peter Timms, Alessandra D. Whaite, Elizabeth A. Jones, Katherine Belov, Adam PolkinghorneAbstract:Infectious Diseases are contributing to the decline of the iconic Australian marsupial, the koala (Phascolarctos cinereus). Infections with the obligate intracellular bacteria, Chlamydia pecorum, cause debilitating ocular and Urogenital-Tract Disease while the koala-retrovirus (KoRV) has been implicated in host immunosuppression and exacerbation of chlamydial pathogenesis. Although histological studies have provided insight into the basic architecture of koala immune tissues, our understanding of the koala immune response to infectious Disease has been limited, until recently, by a lack of species-specific immune reagents. Recent advances in the characterisation of key immune genes have focused on advancing our understanding of the immune response to Chlamydia infection, revealing commonalities in Disease pathologies and immunity between koalas and other hosts and paving the way for the development of a koala Chlamydia vaccine. This review summarises these recent findings and highlights key aspects of the koala immune system requiring further attention with particular regard to their most prominent infectious Diseases.
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Epidemiology of chlamydial infection and Disease in a free-ranging koala (Phascolarctos cinereus) population
PloS one, 2017Co-Authors: Sharon Nyari, Adam Polkinghorne, Courtney A. Waugh, Jianbao Dong, Bonnie L. Quigley, J. Hanger, Joanne Loader, Peter TimmsAbstract:Chlamydial Disease continues to be one of the main factors threatening the long-term survival of the koala (Phascolarctos cinereus). Despite this, large epidemiological studies of chlamydial infection and Disease in wild koala populations are lacking. A better understanding of the prevalence, transmission and pathogenesis is needed to improve control measures, such as the development of vaccines. We investigated the prevalence of Chlamydia pecorum infection and Disease in 160 koalas in a peri-urban wild population in Queensland, Australia and found that 31% of koalas were Chlamydia PCR positive and 28% had clinically detectable chlamydial Disease. Most infections were at the Urogenital site (27%; both males and females) with only 14% at the ocular site. Interestingly, we found that 27% (4/15) of koalas considered to be sexually immature (9–13 months) were already infected with C. pecorum, suggesting that a significant percentage of animals are infected directly from their mother. Ocular infection levels were less prevalent with increasing age (8% in koalas older than 4 years), whereas the prevalence of Urogenital Tract infections remained high into older age (26% in koalas older than 4 years), suggesting that, after mother-to-young transmission, C. pecorum is predominantly a sexually transmitted infection. While 28% of koalas in this population had clinically detectable chlamydial Disease (primarily Urogenital Tract Disease), many PCR positive koalas had no detectable Disease and importantly, not all Diseased animals were PCR positive. We also observed higher chlamydial loads in koalas who were C. pecorum infected without clinical Disease than in koalas who were C. pecorum infected with clinical Disease. These results shed light on the potential mechanisms of transmission of C. pecorum in koalas and also guide future control measures, such as vaccination.
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Chlamydia pecorum: successful pathogen of koalas or Australian livestock?
Microbiology Australia, 2017Co-Authors: Martina Jelocnik, Adam PolkinghorneAbstract:In Australia, the obligate intracellular bacterium Chlamydia pecorum is best known as the notorious koala pathogen that causes debilitating ocular and Urogenital Tract Disease. While globally published data suggests that this species is essentially ubiquitous in livestock, little is known about the epidemiology of livestock C. pecorum infections here in Australia. My research is focused on investigating the genetic diversity and transmission patterns of C. pecorum, and why it causes Disease. Using our newly developed C. pecorum-specific molecular epidemiology typing scheme we provided the first epidemiological data on infections in sheep and cattle in Australia, identifying strains associated with a range of Diseases in livestock, and uncovering an unexpected level of diversity for this pathogen. Most importantly, we observed that the same strain can infect koala and sheep, indicating on ongoing cross-host transmission and ‘spill-over' risks to wildlife. Further, by dissecting koala, sheep, cattle and pig C. pecorum strains genomes, we have also identified novel virulence-associated factors that could be explored as vaccine candidates for both livestock and koala infections.
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PREVALENCE AND PATHOLOGIC FEATURES OF CHLAMYDIA PECORUM INFECTIONS IN SOUTH AUSTRALIAN KOALAS (PHASCOLARCTOS CINEREUS)
Journal of wildlife diseases, 2016Co-Authors: K. Natasha Speight, Peter Timms, Adam Polkinghorne, Rachel Penn, Wayne Boardman, Tamieka A. Fraser, Kathryn Johnson, Rachel Faull, Sarah Bate, Lucy WoolfordAbstract:Chlamydia pecorum infection is highly prevalent in many koala ( Phascolarctos cinereus ) populations in the eastern states of Australia, causing ocular and Urogenital Tract Disease. In contrast, the current prevalence of chlamydiosis in South Australian (SA) koalas is largely unknown, with few reports of clinical cases. We examined 65 SA rescued wild koalas at necropsy and collected ocular and Urogenital swabs for the detection of C. pecorum by PCR. We detected C. pecorum in ocular or Urogenital swabs from 57 koalas (88%), and 34 koalas were positive at both ocular and Urogenital sites. Clinically overt chlamydial Disease was present in only 12 (21%) positive koalas. Gross lesions were often externally inapparent as they affected the Urogenital Tract (n=5), and 24 infected koalas had microscopically evident lesions only. Lesions were predominantly mild and included conjunctivitis, cystitis, and urethritis. Reproductive Tract Disease was infrequently observed. We detected C. pecorum in 16 (28%) koalas with no evidence of chlamydial Disease, suggesting the presence of subclinical carriers in this population. Based on these findings, chlamydiosis has a higher occurrence in SA koala populations than previously thought, but is most often mild and does not always result in overt clinical Disease; inapparent and subclinical infections appear common. Further studies of the prevalence in wild-caught SA koalas are needed along with research into the host and bacterial factors that may influence Disease outcome in these animals.
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using quantitative polymerase chain reaction to correlate chlamydia pecorum infectious load with ocular urinary and reproductive Tract Disease in the koala phascolarctos cinereus
Australian Veterinary Journal, 2011Co-Authors: Charles Wan, Jon Hanger, Jo Loader, Kenneth W Beagley, Peter Timms, Adam PolkinghorneAbstract:Complex interactions between Chlamydia pecorum infection, the immune response and Disease exist in the koala. We used quantitative polymerase chain reaction to investigate the relationship between C. pecorum infectious load and ocular and Urogenital Tract Disease. Chlamydia pecorum shedding was generally higher in animals with chronic, active Disease than in animals with inactive Disease. The absence of ocular Disease was generally associated with low levels of shedding, but relatively high levels of shedding in the Urogenital Tract were detected in some koalas without clinical Disease signs. These results suggest a complex Disease pathogenesis and clinical course in C. pecorum-infected koalas.
Leticia Reyes - One of the best experts on this subject based on the ideXlab platform.
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different inflammatory responses are associated with ureaplasma parvum induced uti and urolith formation
BMC Infectious Diseases, 2009Co-Authors: Leticia Reyes, Mary K Reinhard, Mary B BrownAbstract:Background Epidemiologic studies show a strong association between Ureaplasmas and Urogenital Tract Disease in humans. Since healthy humans can be colonized with Ureaplasmas, its role as a pathogen remains controversial. In order to begin to define the role of the host in Disease, we developed a rodent model of urinary Tract infection (UTI) using Fischer 344 (F344) rats. Animals were inoculated with sterile broth, 101, 103, 105, 107, or 109 log CFU of a rat-adapted strain of Ureaplasma parvum.
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Different inflammatory responses are associated with Ureaplasma parvum-induced UTI and urolith formation
BMC Infectious Diseases, 2009Co-Authors: Leticia Reyes, Mary Reinhard, Mary B BrownAbstract:Background Epidemiologic studies show a strong association between Ureaplasmas and Urogenital Tract Disease in humans. Since healthy humans can be colonized with Ureaplasmas , its role as a pathogen remains controversial. In order to begin to define the role of the host in Disease, we developed a rodent model of urinary Tract infection (UTI) using Fischer 344 (F344) rats. Animals were inoculated with sterile broth, 10^1, 10^3, 10^5, 10^7, or 10^9 log CFU of a rat-adapted strain of Ureaplasma parvum . Results Infected animals exhibited two distinct profiles, asymptomatic UTI and UTI complicated with struvite urolithiasis. Inoculum dose of U. parvum affected the incidence of UTI, and 50% to 57% of animals inoculated with ≥ 10^7 CFU of U. parvum remained infected (p < 0.04). However, inoculum dose did not influence immune response to U. parvum . Asymptomatic UTI was characterized by a minimal immune response that was predominantly monocytic and lymphocytic, with limited lesions, and elevated urinary levels of IFN-γ, IL-18 and MCP-1 (P ≤ 0.02). UTI complicated with struvite formation was characterized by an exaggerated immune response that was mostly neutrophilic (P ≤ 0.0001), with lesions that showed extensive uroepithelial hyperplasia (P ≤ 0.0001), and a predominance of IL-1α, IL-1β, and GRO/KC in the urine (P ≤ 0.02). Animals with asymptomatic UTI also had a significantly high rate of kidney infection (P ≤ 0.0005). Conclusion Complications associated with U. parvum infection are primarily dependent upon host-specific factors rather than Ureaplasma microbial load. The immune response in F344 rats is similar to that which occurs in humans with ureaplasmal associated Disease. Therefore, this model of infection is a useful tool for elucidating U. parvum -host interactions that confer UTI and Disease.
Celine H. Frère - One of the best experts on this subject based on the ideXlab platform.
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Developing noninvasive methodologies to assess koala population health through detecting Chlamydia from scats.
Molecular Ecology Resources, 2019Co-Authors: Romane H. Cristescu, Russell L. Miller, Anthony J. Schultz, L. Hulse, Damian Jaccoud, Stephen D. Johnston, Jon Hanger, Rosie Booth, Celine H. FrèreAbstract:Wildlife Diseases are a recognized driver of global biodiversity loss, have substantial economic impacts, and are increasingly becoming a threat to human health. Disease surveillance is critical but remains difficult in the wild due to the substantial costs and potential biases associated with most Disease detection methods. Noninvasive scat surveys have been proposed as a health monitoring methodology to overcome some of these limitations. Here, we use the known threat of Chlamydia Disease to the iconic, yet vulnerable, koala Phascolarctos cinereus to compare three methods for Chlamydia detection in scats: multiplex quantitative PCR, next generation sequencing, and a detection dog specifically trained on scats from Chlamydia-infected koalas. All three methods demonstrated 100% specificity, while sensitivity was variable. Of particular interest is the variable sensitivity of these diagnostic tests to detect sick individuals (i.e., not only infection as confirmed by Chlamydia-positive swabs, but with observable clinical signs of the Disease); for koalas with Urogenital Tract Disease signs, sensitivity was 78% with quantitative PCR, 50% with next generation genotyping and 100% with the detection dog method. This may be due to molecular methods having to rely on high-quality DNA whereas the dog most likely detects volatile organic compounds. The most appropriate diagnostic test will vary with Disease prevalence and the specific aims of Disease surveillance. Acknowledging that detection dogs might not be easily accessible to all, the future development of affordable and portable "artificial noses" to detect Diseases from scats in the field might enable cost-effective, rapid and large-scale Disease surveillance.