ABSTRACT
Devil facial tumour 1 (DFT1) is a transmissible cancer clone endangering the Tasmanian devil. The expansion of DFT1 across Tasmania has been documented, but little is known of its evolutionary history. We analysed genomes of 648 DFT1 tumours collected throughout the disease range between 2003 and 2018. DFT1 diverged early into five clades, three spreading widely and two failing to persist. One clade has replaced others at several sites, and rates of DFT1 coinfection are high. DFT1 gradually accumulates copy number variants (CNVs), and its telomere lengths are short but constant. Recurrent CNVs reveal genes under positive selection, sites of genome instability, and repeated loss of a small derived chromosome. Cultured DFT1 cell lines have increased CNV frequency and undergo highly reproducible convergent evolution. Overall, DFT1 is a remarkably stable lineage whose genome illustrates how cancer cells adapt to diverse environments and persist in a parasitic niche.
Subject(s)
Facial Neoplasms/veterinary , Marsupialia/genetics , Animal Diseases/epidemiology , Animal Diseases/genetics , Animal Diseases/transmission , Animals , DNA Copy Number Variations , Evolution, Molecular , Facial Neoplasms/epidemiology , Facial Neoplasms/genetics , Female , Genomic Instability , Male , Phylogeny , Tasmania/epidemiology , Telomere Shortening/genetics , Tumor Cells, CulturedABSTRACT
OBJECTIVE: To evaluate the feasibility of testing and treating people who inject drugs at a supervised injecting facility for hepatitis C virus (HCV) infection. DESIGN: Retrospective cohort study. SETTING, PARTICIPANTS: People who inject drugs who attended the Melbourne supervised injecting facility, 30 June 2018 - 30 June 2020. MAIN OUTCOME MEASURES: Proportion of people tested for hepatitis C; proportions of people positive for anti-HCV antibody and HCV RNA, and of eligible people prescribed direct-acting antiviral (DAA) treatment; sustained virological response twelve weeks or more after treatment completion. RESULTS: Of 4649 people who attended the supervised injecting facility during 2018-20, 321 were tested for hepatitis C (7%); 279 were anti-HCV antibody-positive (87%), of whom 143 (51%) were also HCV RNA-positive. Sixty-four of 321 had previously been treated for hepatitis C (20%), 21 had clinically identified cirrhosis (7%), eight had hepatitis B infections (2%), and four had human immunodeficiency virus infections (1%). In multivariate analyses, people tested for hepatitis C were more likely than untested clients to report psychiatric illness (adjusted odds ratio [aOR], 9.65; 95% confidence interval [CI], 7.26-12.8), not have a fixed address (aOR, 1.59; 95% CI, 1.18-2.14), and to report significant alcohol use (aOR, 1.57; 95% CI, 1.06-2.32). The median number of injecting facility visits was larger for those tested for hepatitis C (101; interquartile range [IQR], 31-236) than for those not tested (20; IQR, 3-90). DAA treatment was prescribed for 126 of 143 HCV RNA-positive clients (88%); 41 of 54 with complete follow-up data were cured (76%). CONCLUSIONS: People who attend supervised injecting facilities can be tested and treated for hepatitis C on site. Models that provide streamlined, convenient hepatitis C care promote engagement with treatment in a group in which the prevalence of hepatitis C is high.
Subject(s)
Drug Users , Hepatitis C, Chronic , Hepatitis C , Substance Abuse, Intravenous , Humans , Antiviral Agents/therapeutic use , Hepacivirus/genetics , Needle-Exchange Programs , Retrospective Studies , Hepatitis C, Chronic/drug therapy , Substance Abuse, Intravenous/complications , Substance Abuse, Intravenous/epidemiology , Hepatitis C/diagnosis , Hepatitis C/drug therapy , Hepatitis C/epidemiology , Australia/epidemiology , RNA/therapeutic useABSTRACT
Clonally transmissible cancers are somatic cell lineages that are spread between individuals via the transfer of living cancer cells. There are only three known naturally occurring transmissible cancers, and these affect dogs, soft-shell clams, and Tasmanian devils, respectively. The Tasmanian devil transmissible facial cancer was first observed in 1996, and is threatening its host species with extinction. Until now, this disease has been consistently associated with a single aneuploid cancer cell lineage that we refer to as DFT1. Here we describe a second transmissible cancer, DFT2, in five devils located in southern Tasmania in 2014 and 2015. DFT2 causes facial tumors that are grossly indistinguishable but histologically distinct from those caused by DFT1. DFT2 bears no detectable cytogenetic similarity to DFT1 and carries a Y chromosome, which contrasts with the female origin of DFT1. DFT2 shows different alleles to both its hosts and DFT1 at microsatellite, structural variant, and major histocompatibility complex (MHC) loci, confirming that it is a second cancer that can be transmitted between devils as an allogeneic, MHC-discordant graft. These findings indicate that Tasmanian devils have spawned at least two distinct transmissible cancer lineages and suggest that transmissible cancers may arise more frequently in nature than previously considered. The discovery of DFT2 presents important challenges for the conservation of Tasmanian devils and raises the possibility that this species is particularly prone to the emergence of transmissible cancers. More generally, our findings highlight the potential for cancer cells to depart from their hosts and become dangerous transmissible pathogens.
Subject(s)
Marsupialia/physiology , Neoplasms/veterinary , Alleles , Animals , Chromosome Breakage , Cytogenetic Analysis , Exons/genetics , Genome , Geography , Haplotypes/genetics , Karyotyping , Microsatellite Repeats/genetics , Molecular Sequence Data , Neoplasms/genetics , Neoplasms/pathology , Polymorphism, Single Nucleotide/genetics , Tasmania , X Chromosome/geneticsABSTRACT
BACKGROUND: To achieve hepatitis C virus (HCV) elimination targets, simplified care engaging people who inject drugs is required. We evaluated whether fingerstick HCV RNA point-of-care testing (PoCT) increased the proportion of clients attending a supervised injecting facility who were tested for hepatitis C. METHODS: Prospective single-arm study with recruitment between 9 November 2020 and 28 January 2021 and follow-up to 31 July 2021. Clients attending the supervised injecting facility were offered HCV RNA testing using the Xpert® HCV Viral Load Fingerstick (Cepheid, Sunnyvale, CA) PoCT. Participants with a positive HCV RNA test were prescribed direct acting antiviral (DAA) therapy. The primary endpoint was the proportion of clients who engaged in HCV RNA PoCT, compared to a historical comparator group when venepuncture-based hepatitis C testing was standard of care. RESULTS: Among 1618 clients who attended the supervised injecting facility during the study period, 228 (14%) engaged in PoCT. This was significantly higher than that observed in the historical comparator group (61/1,775, 3%; p < 0.001). Sixty-five (28%) participants were HCV RNA positive, with 40/65 (62%) receiving their result on the same day as testing. Sixty-one (94%) HCV RNA positive participants were commenced on DAA therapy; 14/61 (23%) started treatment on the same day as diagnosis. There was no difference in the proportion of HCV RNA positive participants commenced on treatment with DAA therapy when compared to the historical comparator group (61/65, 94% vs 22/26, 85%; p = 0.153). However, the median time to treatment initiation was significantly shorter in the PoCT cohort (2 days (IQR 1-20) vs 41 days (IQR 22-76), p < 0.001). Among participants who commenced treatment and had complete follow-up data available, 27/36 (75%) achieved hepatitis C cure. CONCLUSIONS: HCV RNA PoCT led to a significantly higher proportion of clients attending a supervised injecting facility engaging in hepatitis C testing, whilst also reducing the time to treatment initiation.
Subject(s)
Drug Users , Hepatitis C, Chronic , Hepatitis C , Substance Abuse, Intravenous , Humans , Antiviral Agents , Needle-Exchange Programs , Point-of-Care Systems , Prospective Studies , Hepatitis C, Chronic/drug therapy , Hepatitis C/diagnosis , Hepatitis C/drug therapy , Hepatitis C/epidemiology , Point-of-Care Testing , Hepacivirus/genetics , RNA, ViralABSTRACT
The iForma ConforMIS Interpositional knee device is a recently developed patient specific implant used for the treatment of mild to moderate uni-compartmental osteoarthritis. The benefits over traditional methods of surgical management are: it is less invasive, can be performed as a day procedure and does not limit future options. Bespoke implants are produced from data extracted from MRIs. Twenty-six patients with the iForma ConforMIS interpositional knee implant from November 2007 were retrospectively reviewed. The average age was 54.7 years, The average pre-operative WOMAC score was 37.8 improving to 67.6 post-operatively. Five patients required revision. No dislocations were reported. Our early experience suggests this device is a viable and safe treatment option. However, patient selection plays an important role in the outcome following surgery and long term results should be awaited.
Subject(s)
Arthroplasty, Replacement, Knee/methods , Knee Joint/surgery , Knee Prosthesis , Osteoarthritis, Knee/surgery , Prosthesis Design , Adult , Aged , Arthroplasty, Replacement, Knee/instrumentation , Female , Humans , Male , Middle Aged , Retrospective Studies , Treatment OutcomeABSTRACT
According to the national joint registry, patello-femoral joint (PFJ) replacement accounts for 1% of all knee arthroplasty procedures in the UK, 1014 of which were performed in 2018. The femoro-patella vialla (FPV) implant by MicroPort orthopaedics has a high reported rate of revision, more than four times that of other knee replacements. The mechanisms of failure are usually loss of fixation at the bone-implant interface. We observe a rare and unusual case form of patella component failure whereby the facets of the implant remain imbedded within the patella as a result of shear force, leaving a loose patella button within the knee. A literature review was conducted of reported modes of failure of the FPV implant and retrospective analysis of our units' results looking into rate of revision, modes of failure, and assessment of a single surgeon's patient outcome measure (Knee Society Scores). Retrospective analysis of our hospital's data revealed that 11% of FPV implants were revised in our unit, a large percentage of which were due to pain and progressive osteoarthritis. We observed revision rates of 5.84% at 3 years, 10.21% at 5 years, and 13.13% at 10 years, which is favourable to national joint registry revision estimates of 6.99%, 10.13%, and 19.10%, respectively. Knee Society Scores reveal a mean improvement of 39.65 (-38 to 100) at follow-up following FPV unicompartmental knee arthroplasty surgery. Our unit demonstrated better results from patient outcome measures when compared to literature and a lower rate of revision when compared to national figures.
ABSTRACT
Changes in life history are expected when new sources of extrinsic mortality impact on natural populations. We report a new disease, devil facial tumor disease, causing an abrupt transition from iteroparity toward single breeding in the largest extant carnivorous marsupial, the Tasmanian devil (Sarcophilus harrisii), in which males can weigh as much as 14 kg and females 9 kg. This change in life history is associated with almost complete mortality of individuals from this infectious cancer past their first year of adult life. Devils have shown their capacity to respond to this disease-induced increased adult mortality with a 16-fold increase in the proportion of individuals exhibiting precocious sexual maturity. These patterns are documented in five populations where there are data from before and after disease arrival and subsequent population impacts. To our knowledge, this is the first known case of infectious disease leading to increased early reproduction in a mammal. The persistence of both this disease and the associated life-history changes pose questions about longer-term evolutionary responses and conservation prospects for this iconic species.
Subject(s)
Marsupialia/growth & development , Adaptation, Physiological , Age Factors , Animals , Ecosystem , Female , Male , Marsupialia/physiology , Neoplasms/etiology , Neoplasms/physiopathology , Neoplasms/veterinary , Population Dynamics , Reproduction , Sexual Maturation , TasmaniaABSTRACT
BACKGROUND: Vulnerable species experiencing inbreeding depression are prone to localised extinctions because of their reduced fitness. For Tasmanian devils, the rapid spread of devil facial tumour disease (DFTD) has led to population declines and fragmentation across the species' range. Here we show that one of the few remaining DFTD-free populations of Tasmanian devils is experiencing inbreeding depression. Moreover, this population has experienced a significant reduction in reproductive success over recent years. METHODS: We used 32 microsatellite loci to examine changes in genetic diversity and inbreeding in the wild population at Woolnorth, alongside field data on breeding success from females to test for inbreeding depression. RESULTS: Wefound that maternal internal relatedness has a negative impact on litter sizes. The results of this study imply that this population may be entering an extinction vortex and that to protect the population genetic rescue should be considered. This study provides conservation managers with useful information for managing wild devils and provides support for the "Wild Devil Recovery Program", which is currently augmenting small, isolated populations.
ABSTRACT
Introduction: The Tasmanian devil (Sarcophilus harrisii) is the largest extant carnivorous marsupial. Since 1996, its population has declined by 77% primarily due to a clonal transmissible tumor, known as devil facial tumor (DFT1) disease. In 2014, a second transmissible devil facial tumor (DFT2) was discovered. DFT1 and DFT2 are nearly 100% fatal.Areas covered: We review DFT control approaches and propose a rabies-style oral bait vaccine (OBV) platform for DFTs. This approach has an extensive safety record and was a primary tool in large-scale rabies virus elimination from wild carnivores across diverse landscapes. Like rabies virus, DFTs are transmitted by oral contact, so immunizing the oral cavity and stimulating resident memory cells could be advantageous. Additionally, exposing infected devils that already have tumors to OBVs could serve as an oncolytic virus immunotherapy. The primary challenges may be identifying appropriate DFT-specific antigens and optimization of field delivery methods.Expert opinion: DFT2 is currently found on a peninsula in southern Tasmania, so an OBV that could eliminate DFT2 should be the priority for this vaccine approach. Translation of an OBV approach to control DFTs will be challenging, but the approach is feasible for combatting ongoing and future disease threats.
Subject(s)
Cancer Vaccines/administration & dosage , Facial Neoplasms/prevention & control , Vaccination/methods , Administration, Oral , Animals , Cancer Vaccines/immunology , Facial Neoplasms/immunology , Facial Neoplasms/veterinary , Humans , Immunotherapy/methods , Marsupialia/immunology , Oncolytic Virotherapy/methods , Tasmania , Vaccination/veterinaryABSTRACT
For bottlenecked populations of threatened species, supplementation often leads to improved population metrics (genetic rescue), provided that guidelines can be followed to avoid negative outcomes. In cases where no "ideal" source populations exist, or there are other complicating factors such as prevailing disease, the benefit of supplementation becomes uncertain. Bringing multiple data and analysis types together to plan genetic management activities can help. Here, we consider three populations of Tasmanian devil, Sarcophilus harrisii, as candidates for genetic rescue. Since 1996, devil populations have been severely impacted by devil facial tumour disease (DFTD), causing significant population decline and fragmentation. Like many threatened species, the key threatening process for devils cannot currently be fully mitigated, so species management requires a multifaceted approach. We examined diversity of 31 putatively neutral and 11 MHC-linked microsatellite loci of three remnant wild devil populations (one sampled at two time-points), alongside computational diversity projections, parameterized by field data from DFTD-present and DFTD-absent sites. Results showed that populations had low diversity, connectivity was poor, and diversity has likely decreased over the last decade. Stochastic simulations projected further diversity losses. For a given population size, the effects of DFTD on population demography (including earlier age at death and increased female productivity) did not impact diversity retention, which was largely driven by final population size. Population sizes ≥500 (depending on the number of founders) were necessary for maintaining diversity in otherwise unmanaged populations, even if DFTD is present. Models indicated that smaller populations could maintain diversity with ongoing immigration. Taken together, our results illustrate how multiple analysis types can be combined to address complex population genetic challenges.
ABSTRACT
BACKGROUND: The prevalence of hepatitis C virus (HCV) has been reported to be high among people experiencing homelessness. People who are homeless often have multiple needs that may take precedence over HCV testing and treatment. We quantitatively evaluated the outcomes of a service providing HCV treatment to people attending homeless services. METHODS: Clients attending homeless services were referred to a nurse specialising in HCV-related care. The nurse provided HCV testing, education and case-management while prescriptions were provided by an affiliated doctor. Logistic regression was used to explore factors associated with treatment commencement. RESULTS: Fifty-two clients referred (78%) underwent testing, thirty-nine were HCV-RNA positive among whom 18 (46%) reported sleeping rough and 29 (74%) reported injecting drug use; 66% had injected less than three months ago. Twenty-four (62%) clients commenced treatment, of whom thirteen (54%) had a sustained virological response test; all were cured. Treatment commencement was lower among people who reported sleeping rough (aOR 0.15, 95%CI 0.029-0.73). There was no difference in treatment commencement based on injecting drugs (aOR 1.06, 95%CI 0.21-5.2). CONCLUSION: Most clients' commenced treatment and the majority were successfully cured using a dedicated nursing service. Clients who reported sleeping rough may still face personal and/or system level barriers to HCV treatment.
Subject(s)
Delivery of Health Care/organization & administration , Hepatitis C/nursing , Ill-Housed Persons , Substance Abuse, Intravenous/epidemiology , Adult , Aged , Australia , Drug Users/statistics & numerical data , Female , Hepatitis C/diagnosis , Hepatitis C/epidemiology , Humans , Male , Middle Aged , RNA, Viral/isolation & purification , Sustained Virologic Response , Young AdultABSTRACT
Emerging infectious diseases are rising globally and understanding host-pathogen interactions during the initial stages of disease emergence is essential for assessing potential evolutionary dynamics and designing novel management strategies. Tasmanian devils (Sarcophilus harrisii) are endangered due to a transmissible cancer-devil facial tumour disease (DFTD)-that since its emergence in the 1990s, has affected most populations throughout Tasmania. Recent studies suggest that devils are adapting to the DFTD epidemic and that disease-induced extinction is unlikely. However, in 2014, a second and independently evolved transmissible cancer-devil facial tumour 2 (DFT2)-was discovered at the d'Entrecasteaux peninsula, in south-east Tasmania, suggesting that the species is prone to transmissible cancers. To date, there is little information about the distribution, epidemiology and effects of DFT2 and its interaction with DFTD. Here, we use data from monitoring surveys and roadkills found within and adjacent to the d'Entrecasteaux peninsula to determine the distribution of both cancers and to compare their epidemiological patterns. Since 2012, a total of 51 DFTD tumours have been confirmed among 26 individuals inside the peninsula and its surroundings, while 40 DFT2 tumours have been confirmed among 23 individuals, and two individuals co-infected with both tumours. All devils with DFT2 were found within the d'Entrecasteaux peninsula, suggesting that this new transmissible cancer is geographically confined to this area. We found significant differences in tumour bodily location in DFTD and DFT2, with non-facial tumours more commonly found in DFT2. There was a significant sex bias in DFT2, with most cases reported in males, suggesting that since DFT2 originated from a male host, females might be less susceptible to this cancer. We discuss the implications of our results for understanding the epidemiological and evolutionary interactions of these two contemporary transmissible cancers and evaluating the effectiveness of potential management strategies.
ABSTRACT
The Tasmanian devil, a marsupial carnivore, has been restricted to the island state of Tasmania since its extinction on the Australian mainland about 3000 years ago. In the past two decades, this species has experienced severe population decline due to the emergence of devil facial tumor disease (DFTD), a transmissible cancer. During these 20 years, scientists have puzzled over the immunological and evolutionary responses by the Tasmanian devil to this transmissible cancer. Targeted strategies in population management and disease control have been developed as well as comparative processes to identify variation in tumor and host genetics. A multi-disciplinary approach with multi-institutional teams has produced considerable advances over the last decade. This has led to a greater understanding of the molecular pathogenesis and genomic classification of this cancer. New and promising developments in the Tasmanian devil's story include evidence that most immunized, and some wild devils, can produce an immune response to DFTD. Furthermore, epidemiology combined with genomic studies suggest a rapid evolution to the disease and that DFTD will become an endemic disease. Since 1998 there have been more than 350 publications, distributed over 37 Web of Science categories. A unique endemic island species has become an international curiosity that is in the spotlight of integrative and comparative biology research.
Subject(s)
Disease Transmission, Infectious/veterinary , Facial Neoplasms/veterinary , Animals , Disease Transmission, Infectious/prevention & control , Facial Neoplasms/immunology , Facial Neoplasms/pathology , Facial Neoplasms/prevention & control , Marsupialia , TasmaniaABSTRACT
1. Monitoring the response of wild mammal populations to threatening processes is fundamental to effective conservation management. This is especially true for infectious diseases, which may have dynamic and therefore unpredictable interactions with their host. 2. We investigate the long-term impact of a transmissible cancer, devil facial tumour disease (DFTD), on the endemic Tasmanian devil. We analyse trends in devil spot-light counts and density across the area impacted by the disease. We investigate the demographic parameters which might be driving these trends, and use spatial capture-recapture models to examine whether DFTD has affected home range size. 3. We found that devils have declined by an average of 77% in areas affected by DFTD, and that there is a congruent trend of ongoing small decline in spotlight counts and density estimates. Despite this, devils have persisted to date within each of nine monitoring sites. One site is showing as yet unexplained small increases in density 8-10 years after the emergence of DFTD. 4. We also found the prevalence of DFTD has not abated despite large declines in density and that diseased sites continue to be dominated by young devils. The long-term impact of the disease has been partially offset by increased fecundity in the form of precocial breeding in 1-year-old females, and more pouch young per female in diseased sites. The lower densities resulting from DFTD did not affect home range size. 5. Synthesis and applications. Transmission of devil facial tumour disease continues despite large declines in devil density over multiple generations. Plasticity in life history traits has ameliorated the impact of devil facial tumour disease, however broad-scale trends in density show ongoing decline. In light of this, devil facial tumour disease and the impact of stochastic events on the reduced densities wrought by the disease, continue to threaten devils. In the absence of methods to manage disease in wild populations, we advocate managing the low population densities resulting from disease rather than disease per se.
ABSTRACT
Tasmanian devils have spawned two transmissible cancer clones, known as devil facial tumour 1 (DFT1) and devil facial tumour 2 (DFT2). DFT1 and DFT2 are transmitted between animals by the transfer of allogeneic contagious cancer cells by biting, and both cause facial tumours. DFT1 and DFT2 tumours are grossly indistinguishable, but can be differentiated using histopathology, cytogenetics or genotyping of polymorphic markers. However, standard diagnostic methods require specialist skills and equipment and entail long processing times. Here, we describe Tasman-PCR: a simple polymerase chain reaction (PCR)-based diagnostic assay that identifies and distinguishes DFT1 and DFT2 by amplification of DNA spanning tumour-specific interchromosomal translocations. We demonstrate the high sensitivity and specificity of this assay by testing DNA from 546 tumours and 804 normal devils. A temporal-spatial screen confirmed the reported geographic ranges of DFT1 and DFT2 and did not provide evidence of additional DFT clones. DFT2 affects disproportionately more males than females, and devils can be co-infected with DFT1 and DFT2. Overall, we present a PCR-based assay that delivers rapid, accurate and high-throughput diagnosis of DFT1 and DFT2. This tool provides an additional resource for devil disease management and may assist with ongoing conservation efforts.
ABSTRACT
Devil facial tumor disease (DFTD) is renowned for its successful evasion of the host immune system. Down regulation of the major histocompatabilty complex class I molecule (MHC-I) on the DFTD cells is a primary mechanism of immune escape. Immunization trials on captive Tasmanian devils have previously demonstrated that an immune response against DFTD can be induced, and that immune-mediated tumor regression can occur. However, these trials were limited by their small sample sizes. Here, we describe the results of two DFTD immunization trials on cohorts of devils prior to their wild release as part of the Tasmanian Government's Wild Devil Recovery project. 95% of the devils developed anti-DFTD antibody responses. Given the relatively large sample sizes of the trials (N = 19 and N = 33), these responses are likely to reflect those of the general devil population. DFTD cells manipulated to express MHC-I were used as the antigenic basis of the immunizations in both trials. Although the adjuvant composition and number of immunizations differed between trials, similar anti-DFTD antibody levels were obtained. The first trial comprised DFTD cells and the adjuvant combination of ISCOMATRIX™, polyIC, and CpG with up to four immunizations given at monthly intervals. This compared to the second trial whereby two immunizations comprising DFTD cells and the adjuvant combination ISCOMATRIX™, polyICLC (Hiltonol®) and imiquimod were given a month apart, providing a shorter and, therefore, more practical protocol. Both trials incorporated a booster immunization given up to 5 months after the primary course. A key finding was that devils in the second trial responded more quickly and maintained their antibody levels for longer compared to devils in the first trial. The different adjuvant combination incorporating the RNAase resistant polyICLC and imiquimod used in the second trial is likely to be responsible. The seroconversion in the majority of devils in these anti-DFTD immunization trials was remarkable, especially as DFTD is hallmarked by its immune evasion mechanisms. Microsatellite analyzes of MHC revealed that some MHC-I microsatellites correlated to stronger immune responses. These trials signify the first step in the long-term objective of releasing devils with immunity to DFTD into the wild.
Subject(s)
Adjuvants, Immunologic , Cancer Vaccines/immunology , Facial Neoplasms/immunology , Immunotherapy/methods , Marsupialia/immunology , Animals , Carboxymethylcellulose Sodium/analogs & derivatives , Female , Histocompatibility Antigens Class I/genetics , Histocompatibility Antigens Class I/metabolism , Imiquimod/immunology , Immunity, Humoral , Immunization, Secondary , Immunoglobulin G/blood , Male , Poly I-C/immunology , Polylysine/analogs & derivatives , Polylysine/immunology , Tumor EscapeABSTRACT
Captive breeding of threatened species, for release to the wild, is critical for conservation. This strategy, however, risks producing captive-raised animals with traits poorly suited to the wild. We describe the first study to characterise accumulated consequences of long-term captive breeding on behaviour, by following the release of Tasmanian devils to the wild. We test the impact of prolonged captive breeding on the probability that captive-raised animals are fatally struck by vehicles. Multiple generations of captive breeding increased the probability that individuals were fatally struck, a pattern that could not be explained by other confounding factors (e.g. age or release site). Our results imply that long-term captive breeding programs may produce animals that are naïve to the risks of the post-release environment. Our analyses have already induced changes in management policy of this endangered species, and serve as model of productive synergy between ecological monitoring and conservation strategy.
Subject(s)
Conservation of Natural Resources , Marsupialia , Animals , Breeding , Endangered Species , Female , MaleABSTRACT
Immunoglobulins such as IgG and IgM have been shown to induce anti-tumour cytotoxic activity. In the present study we therefore explore total serum IgG and IgM expression dynamics in 23 known-aged Tasmanian devils (Sarcophilus harrisii) of which 9 where affected by Devil Facial Tumour Disease (DFTD). DFTD is clonally transmissible cancer that has caused massive declines in devil numbers. Our analyses revealed that IgM and IgG expression levels as well as IgM/IgG ratios decreased with increasing devil age. Neither age, sex, IgM nor IgG expression levels affected devil DFTD status in our analyses. However, devils with increased IgM relative to IgG expression levels had significantly lower DFTD prevalence. Our results therefore suggest that IgM/IgG ratios may play an important role in determining devil susceptibility to DFTD. We consequently propose that our findings warrant further studies to elucidate the underpinning(s) of devil IgM/IgG ratios and DFTD status.
Subject(s)
Facial Neoplasms/epidemiology , Immunoglobulin G/genetics , Immunoglobulin M/genetics , Marsupialia/immunology , Age Factors , Animals , Disease Susceptibility , Facial Neoplasms/immunology , Facial Neoplasms/veterinary , Female , Male , Marsupialia/blood , Marsupialia/classification , Marsupialia/genetics , PrevalenceABSTRACT
BACKGROUND: The Tasmanian devil, the world's largest carnivorous marsupial, is at risk of extinction due to devil facial tumour disease (DFTD), a fatal contagious cancer. The Save the Tasmanian Devil Program has established an insurance population, which currently holds over 600 devils in captive facilities across Australia. Microbes are known to play a crucial role in the health and well-being of humans and other animals, and increasing evidence suggests that changes in the microbiota can influence various aspects of host physiology and development. To improve our understanding of devils and facilitate management and conservation of the species, we characterised the microbiome of wild devils and investigated differences in the composition of microbial community between captive and wild individuals. RESULTS: A total of 1,223,550 bacterial 16S ribosomal RNA (rRNA) sequences were generated via Roche 454 sequencing from 56 samples, including 17 gut, 15 skin, 18 pouch and 6 oral samples. The devil's gut microbiome was dominated by Firmicutes and showed a high Firmicutes-to-Bacteroidetes ratio, which appears to be a common feature of many carnivorous mammals. Metabolisms of carbohydrates, amino acids, energy, cofactors and vitamins, nucleotides and lipids were predicted as the most prominent metabolic pathways that the devil's gut flora contributed to. The microbiota inside the female's pouch outside lactation was highly similar to that of the skin, both co-dominated by Firmicutes and Proteobacteria. The oral microbiome had similar proportions of Proteobacteria, Bacteroidetes, Firmicutes and Fusobacteria. CONCLUSIONS: Compositional differences were observed in all four types of microbiota between devils from captive and wild populations. Certain captive devils had significantly lower levels of gut bacterial diversity than wild individuals, and the two groups differed in the proportion of gut bacteria accounting for the metabolism of glycan, amino acids and cofactors and vitamins. Further studies are underway to investigate whether alterations in the microbiome of captive devils can have impacts on their ability to adapt and survive following re-introduction to the wild.