Molecular and pathological insights into Chlamydia pecorum-associated sporadic bovine encephalomyelitis (SBE) in Western Australia

Jelocnik, Martina; Forshaw, D.; Cotter, Jennifer; Roberts, Danny

doi:10.1186/1746-6148-10-121

Cited by 29 publications

(45 citation statements)

References 30 publications

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“…4). Our group previously provided evidence to suggest that genetically similar, if not identical, strains of C. pecorum can be found in Australian sheep, cattle, and koalas (6,8,39). The whole-genome phylogenies constructed for the strains sequenced from northern New South Wales (Gun/koa1/Ure) and South Australian koalas (SA/k2/UTG) appear to confirm this finding.…”

Section: Discussionsupporting

confidence: 62%

“…In the case of C. pecorum specifically, a previous MLST study on livestock C. pecorum strains showed that a single animal could be infected by multiple strains at different anatomical sites, with speculation only on shedding multiple strains from the same site (8,39). However, this is the first study to reveal the presence of multiple C. pecorum strains at the same anatomical site in both koalas and sheep.…”

Section: Discussionmentioning

confidence: 46%

“…The most likely explanation for this is that the C. pecorum NSW/Bov/SBE isolate cultured was the dominant strain found in the clinical sample at the time of culturing, and its growth was favored to the exclusion of others through subsequent passaging. Alternatively, since this was a brain isolate, it also might reflect the success of this strain in invading the central nervous system over other strains infecting the animal at the same time, a possibility given our recent observation of genetically distinct strains present in the gastrointestinal tract versus central nervous system tissues of calves with SBE (39).…”

Section: Discussionmentioning

confidence: 99%

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Culture-Independent Genome Sequencing of Clinical Samples Reveals an Unexpected Heterogeneity of Infections by Chlamydia pecorum

et al. 2015

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bChlamydia pecorum is an important global pathogen of livestock, and it is also a significant threat to the long-term survival of Australia's koala populations. This study employed a culture-independent DNA capture approach to sequence C. pecorum genomes directly from clinical swab samples collected from koalas with chlamydial disease as well as from sheep with arthritis and conjunctivitis. Investigations into single-nucleotide polymorphisms within each of the swab samples revealed that a portion of the reads in each sample belonged to separate C. pecorum strains, suggesting that all of the clinical samples analyzed contained mixed populations of genetically distinct C. pecorum isolates. This observation was independent of the anatomical site sampled and the host species. Using the genomes of strains identified in each of these samples, whole-genome phylogenetic analysis revealed that a clade containing a bovine and a koala isolate is distinct from other clades comprised of livestock or koala C. pecorum strains. Providing additional evidence to support exposure of koalas to Australian livestock strains, two minor strains assembled from the koala swab samples clustered with livestock strains rather than koala strains. Culture-independent probebased genome capture and sequencing of clinical samples provides the strongest evidence yet to suggest that naturally occurring chlamydial infections are comprised of multiple genetically distinct strains. Chlamydia pecorum is a widespread pathogen of economically important livestock species, such as cattle and sheep. In cattle, C. pecorum is associated with sporadic bovine encephalomyelitis (SBE), which presents as a fever followed by limb stiffness and staggering (1). In sheep, C. pecorum infections commonly are linked to polyarthritis and conjunctivitis, which can spread rapidly in a flock (2, 3). While these infections are economically relevant to producers, most C. pecorum infections in ruminants appear to be asymptomatic or subclinical, characterized by a consistent presence in the gastrointestinal tract (4, 5). While questions remain over the impact of these infections in livestock globally, the best example of the pathogenic potential of this obligate intracellular bacterium actually is found in koalas, a native Australian marsupial that continues to experience localized extinctions. C. pecorum infections in koalas can cause debilitating ocular and urogenital tract diseases (6, 7). Epidemiological questions have been raised about the relationships between C. pecorum strains infecting domesticated animals and the koala, with a recent C. pecorum multilocus sequence typing (MLST) study revealing the presence of identical sequence types in samples collected from each host (8). As a follow-up to these studies, we recently sequenced the genomes of several cultured koala C. pecorum isolates, revealing a high degree of synteny and sequence identity (98.5 to 98.8%) with C. pecorum genomes from European and U.S. cattle and sheep (9).High-throughput comparative genome sequencin...

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Section: Discussionsupporting

confidence: 62%

Section: Discussionmentioning

confidence: 46%

Section: Discussionmentioning

confidence: 99%

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Culture-Independent Genome Sequencing of Clinical Samples Reveals an Unexpected Heterogeneity of Infections by Chlamydia pecorum

et al. 2015

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“…65 By IHC, chlamydial antigen can be demonstrated in the cytoplasm of the endothelium and macrophages of brain, spleen and lung and in the mesothelium. 72 Typing of C. pecorum strains revealed differences between strains detected in brain, heart, lung, liver and the intestine, suggesting that different strains may have different pathogenic potential, an observation that was previously also suggested from studies of sheep. 73 Associations between C. pecorum infection and enteritis or reproductive diseases such as placentitis and abortion, vaginitis, endometritis, mastitis, and orchitis have been reported with shedding of the organism through the fecal or vaginal route.…”

Section: Chlamydia Pecorum In Ruminantsmentioning

confidence: 63%

A Review on Chlamydial Diseases in Animals: Still a Challenge for Pathologists?

2018

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Chlamydiae have a worldwide distribution causing a wide range of diseases in human hosts, livestock, and companion animals as well as in wildlife and exotic species. Moreover, they can persist in their hosts as asymptomatic infections for extended periods of time. The introduction of molecular techniques has revolutionized the Chlamydia field by expanding the host range of known chlamydial species but also by discovering new species and even new families of bacteria in the broader order Chlamydiales. The wide range of hosts, diseases, and tissues affected by chlamydiae complicate the diagnosis such that standard diagnostic approaches for these bacteria are rare. Bacteria of the Chlamydiales order are small and their inclusions are difficult to detect by standard microscopy. With the exception of avian and ovine chlamydiosis, macroscopic and/or histologic changes might not be pathognomic or indicative for a chlamydial infection or even not present at all. Moreover, detection of chlamydial DNA in specimens in the absence of other methods or related pathological lesions questions the significance of such findings. The pathogenic potential of the majority of recently identified Chlamydia-related bacteria remains largely unknown and awaits investigation through experimental or natural infection models including histomorphological characterization of associated lesions. This review aims to summarize the historical background and the most important developments in the field of animal chlamydial research in the past 5 years with a special focus on pathology. It will summarize the current nomenclature, present critical thoughts about diagnostics, and give an update on chlamydial infections in domesticated animals such as livestock, companion animals and birds, as well as free-ranging and captive wild animals such as reptiles, fish, and marsupials.

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“…Even today, with whole genome sequencing readily available, MLST is still often used as the first point to barcode a strain 13 . In an effort to evaluate the overall genetic diversity and relationships between Australian koala, sheep and cattle C. pecorum strains, we developed and applied a C. pecorum-specific MLST to a range of isolates and C. pecorum-positive clinical samples from koalas, Australian sheep and cattle [14][15][16] .…”

Section: Pecorum Molecular Epidemiologymentioning

confidence: 99%

Chlamydia pecorum: successful pathogen of koalas or Australian livestock?

Jelocnik

2017

Microbiol. Aust.

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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.Chlamydiae, known for their obligatory parasitic lifestyle and distinct biphasic life-cycle 1 , are diverse and enigmatic bacteria that infect an astonishing range of hosts 2 . This phylum includes Chlamydia pecorum, a species that constantly remains in the spotlight due to its role as a major threat to the survival of the iconic koalas. In koalas, highly prevalent C. pecorum infections cause ocular disease that can eventually lead to blindness, and urogenital disease that can lead to infertility 3,4 . The pathogenic potential of C. pecorum in economically significant livestock species (cattle, sheep, goats and pigs) has been well documented in Europe and USA, and to a lesser degree elsewhere including The curious case of Chlamydia pecorum infections in AustraliaWhile the koala chlamydial infections are easily the most intensively studied of any wildlife species, almost nothing is known about the prevalence and epidemiology of C. pecorum infections in Australian livestock. Veterinarians from agriculturally productive areas throughout Australia regularly report cases of chlamydiosis in sheep and cattle 8,9 , but the information about the genetic diversity of strains infecting livestock is lacking. A range of previous molecular studies suggested that C. pecorum strains infecting koala are genetically diverse 10,11 ; however, none of the studies investigated how and whether these strains are related to livestock strains. It has been hypothesised that the origin of koala C. pecorum infections is associated with the import of 'presumably C. pecorum infected' livestock in the late 1780s 3 . The encroachment of koala habitats by sheep and cattle farming along the east coast of Australia is common and raises serious questions over the relationships and potential role that cross-host transmission may have in the epidemiology and origin of chlamydial di...

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Molecular and pathological insights into Chlamydia pecorum-associated sporadic bovine encephalomyelitis (SBE) in Western Australia

Cited by 29 publications

References 30 publications

Culture-Independent Genome Sequencing of Clinical Samples Reveals an Unexpected Heterogeneity of Infections by Chlamydia pecorum

Culture-Independent Genome Sequencing of Clinical Samples Reveals an Unexpected Heterogeneity of Infections by Chlamydia pecorum

A Review on Chlamydial Diseases in Animals: Still a Challenge for Pathologists?

Chlamydia pecorum: successful pathogen of koalas or Australian livestock?

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