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1.  Immunology of naturally transmissible tumours 
Immunology  2014;144(1):11-20.
Naturally transmissible tumours can emerge when a tumour cell gains the ability to pass as an infectious allograft between individuals. The ability of these tumours to colonize a new host and to cross histocompatibility barriers contradicts our understanding of the vertebrate immune response to allografts. Two naturally occurring contagious cancers are currently active in the animal kingdom, canine transmissible venereal tumour (CTVT), which spreads among dogs, and devil facial tumour disease (DFTD), among Tasmanian devils. CTVT are generally not fatal as a tumour-specific host immune response controls or clears the tumours after transmission and a period of growth. In contrast, the growth of DFTD tumours is not controlled by the Tasmanian devil's immune system and the disease causes close to 100% mortality, severely impacting the devil population. To avoid the immune response of the host both DFTD and CTVT use a variety of immune escape strategies that have similarities to many single organism tumours, including MHC loss and the expression of immunosuppressive cytokines. However, both tumours appear to have a complex interaction with the immune system of their respective host, which has evolved over the relatively long life of these tumours. The Tasmanian devil is struggling to survive with the burden of this disease and it is only with an understanding of how DFTD passes between individuals that a vaccine might be developed. Further, an understanding of how these tumours achieve natural transmissibility should provide insights into general mechanisms of immune escape that emerge during tumour evolution.
doi:10.1111/imm.12377
PMCID: PMC4264906  PMID: 25187312
cancer; comparative immunology/evolution; MHC; transplantation; tumour immunology
2.  Immunology of naturally transmissible tumours 
Immunology  2014;144(1):11-20.
Naturally transmissible tumours can emerge when a tumour cell gains the ability to pass as an infectious allograft between individuals. The ability of these tumours to colonize a new host and to cross histocompatibility barriers contradicts our understanding of the vertebrate immune response to allografts. Two naturally occurring contagious cancers are currently active in the animal kingdom, canine transmissible venereal tumour (CTVT), which spreads among dogs, and devil facial tumour disease (DFTD), among Tasmanian devils. CTVT are generally not fatal as a tumour-specific host immune response controls or clears the tumours after transmission and a period of growth. In contrast, the growth of DFTD tumours is not controlled by the Tasmanian devil's immune system and the disease causes close to 100% mortality, severely impacting the devil population. To avoid the immune response of the host both DFTD and CTVT use a variety of immune escape strategies that have similarities to many single organism tumours, including MHC loss and the expression of immunosuppressive cytokines. However, both tumours appear to have a complex interaction with the immune system of their respective host, which has evolved over the relatively long life of these tumours. The Tasmanian devil is struggling to survive with the burden of this disease and it is only with an understanding of how DFTD passes between individuals that a vaccine might be developed. Further, an understanding of how these tumours achieve natural transmissibility should provide insights into general mechanisms of immune escape that emerge during tumour evolution.
doi:10.1111/imm.12377
PMCID: PMC4264906  PMID: 25187312
cancer; comparative immunology/evolution; MHC; transplantation; tumour immunology
3.  A tale of two tumours: Comparison of the immune escape strategies of contagious cancers☆ 
Molecular Immunology  2013;55(2):190-193.
Highlights
► There are two naturally occurring contagious cancers, Devil Facial Tumour Disease (DFTD) and Canine Transmissible Venereal Tumour (CTVT). ► Both contagious cancers share mechanisms of immune evasion. ► These mechanisms of immune evasion provide insights into how contagious cancers can emerge.
The adaptive immune system should prevent cancer cells passing from one individual to another, in much the same way that it protects against pathogens. However, in rare cases cancer cells do not die within a single individual, but successfully pass between individuals, escaping the adaptive immune response and becoming a contagious cancer. There are two naturally occurring contagious cancers, Devil Facial Tumour Disease (DFTD), found in Tasmanian devils, and Canine Transmissible Venereal Tumour (CTVT), found in dogs. Despite sharing an ability to pass as allografts, these cancers have a very different impact on their hosts. While DFTD causes 100% mortality among infected devils and has had a devastating impact on the devil population, CTVT co-exists with its host in a manner that does not usually cause death of the dog. Although immune evasion strategies for CTVT have been defined, why DFTD is not rejected as an allograft is not understood. We have made progress in revealing mechanisms of immune evasion for DFTD both in vitro and in vivo, and here we compare how DFTD and CTVT interact with their respective hosts and avoid rejection. Our findings highlight factors that may be important for the evolution of contagious cancers and cancer more generally. Perhaps most importantly, this work has opened up important areas for future research, including the effect of epigenetic factors on immune escape mechanisms and the basis of a vaccine strategy that may protect Tasmanian devils against DFTD.
doi:10.1016/j.molimm.2012.10.017
PMCID: PMC3878782  PMID: 23200636
Contagious cancer; Immune evasion; MHC; Tasmanian devil; Devil facial tumour disease; Canine transmissible venereal tumour; Cancer
4.  How the devil facial tumor disease escapes host immune responses 
Oncoimmunology  2013;2(8):e25235.
The devil facial tumor disease (DFTD) is a contagious cancer that has recently emerged among Tasmanian devils, rapidly decimating the population. We have recently discovered that DFTD cells lose the expression MHC molecules on the cell surface, explaining how this tumor avoids recognition by host CD8+ T cells.
doi:10.4161/onci.25235
PMCID: PMC3782528  PMID: 24083079
contagious cancer; transmissible tumor; Tasmanian devil; DFTD; CTVT; MHC; epigenetics; interferon; extinction; conservation
5.  The tammar wallaby major histocompatibility complex shows evidence of past genomic instability 
BMC Genomics  2011;12:421.
Background
The major histocompatibility complex (MHC) is a group of genes with a variety of roles in the innate and adaptive immune responses. MHC genes form a genetically linked cluster in eutherian mammals, an organization that is thought to confer functional and evolutionary advantages to the immune system. The tammar wallaby (Macropus eugenii), an Australian marsupial, provides a unique model for understanding MHC gene evolution, as many of its antigen presenting genes are not linked to the MHC, but are scattered around the genome.
Results
Here we describe the 'core' tammar wallaby MHC region on chromosome 2q by ordering and sequencing 33 BAC clones, covering over 4.5 MB and containing 129 genes. When compared to the MHC region of the South American opossum, eutherian mammals and non-mammals, the wallaby MHC has a novel gene organization. The wallaby has undergone an expansion of MHC class II genes, which are separated into two clusters by the class III genes. The antigen processing genes have undergone duplication, resulting in two copies of TAP1 and three copies of TAP2. Notably, Kangaroo Endogenous Retroviral Elements are present within the region and may have contributed to the genomic instability.
Conclusions
The wallaby MHC has been extensively remodeled since the American and Australian marsupials last shared a common ancestor. The instability is characterized by the movement of antigen presenting genes away from the core MHC, most likely via the presence and activity of retroviral elements. We propose that the movement of class II genes away from the ancestral class II region has allowed this gene family to expand and diversify in the wallaby. The duplication of TAP genes in the wallaby MHC makes this species a unique model organism for studying the relationship between MHC gene organization and function.
doi:10.1186/1471-2164-12-421
PMCID: PMC3179965  PMID: 21854592
6.  Genome sequence of an Australian kangaroo, Macropus eugenii, provides insight into the evolution of mammalian reproduction and development 
Renfree, Marilyn B | Papenfuss, Anthony T | Deakin, Janine E | Lindsay, James | Heider, Thomas | Belov, Katherine | Rens, Willem | Waters, Paul D | Pharo, Elizabeth A | Shaw, Geoff | Wong, Emily SW | Lefèvre, Christophe M | Nicholas, Kevin R | Kuroki, Yoko | Wakefield, Matthew J | Zenger, Kyall R | Wang, Chenwei | Ferguson-Smith, Malcolm | Nicholas, Frank W | Hickford, Danielle | Yu, Hongshi | Short, Kirsty R | Siddle, Hannah V | Frankenberg, Stephen R | Chew, Keng Yih | Menzies, Brandon R | Stringer, Jessica M | Suzuki, Shunsuke | Hore, Timothy A | Delbridge, Margaret L | Mohammadi, Amir | Schneider, Nanette Y | Hu, Yanqiu | O'Hara, William | Al Nadaf, Shafagh | Wu, Chen | Feng, Zhi-Ping | Cocks, Benjamin G | Wang, Jianghui | Flicek, Paul | Searle, Stephen MJ | Fairley, Susan | Beal, Kathryn | Herrero, Javier | Carone, Dawn M | Suzuki, Yutaka | Sugano, Sumio | Toyoda, Atsushi | Sakaki, Yoshiyuki | Kondo, Shinji | Nishida, Yuichiro | Tatsumoto, Shoji | Mandiou, Ion | Hsu, Arthur | McColl, Kaighin A | Lansdell, Benjamin | Weinstock, George | Kuczek, Elizabeth | McGrath, Annette | Wilson, Peter | Men, Artem | Hazar-Rethinam, Mehlika | Hall, Allison | Davis, John | Wood, David | Williams, Sarah | Sundaravadanam, Yogi | Muzny, Donna M | Jhangiani, Shalini N | Lewis, Lora R | Morgan, Margaret B | Okwuonu, Geoffrey O | Ruiz, San Juana | Santibanez, Jireh | Nazareth, Lynne | Cree, Andrew | Fowler, Gerald | Kovar, Christie L | Dinh, Huyen H | Joshi, Vandita | Jing, Chyn | Lara, Fremiet | Thornton, Rebecca | Chen, Lei | Deng, Jixin | Liu, Yue | Shen, Joshua Y | Song, Xing-Zhi | Edson, Janette | Troon, Carmen | Thomas, Daniel | Stephens, Amber | Yapa, Lankesha | Levchenko, Tanya | Gibbs, Richard A | Cooper, Desmond W | Speed, Terence P | Fujiyama, Asao | M Graves, Jennifer A | O'Neill, Rachel J | Pask, Andrew J | Forrest, Susan M | Worley, Kim C
Genome Biology  2011;12(8):R81.
Background
We present the genome sequence of the tammar wallaby, Macropus eugenii, which is a member of the kangaroo family and the first representative of the iconic hopping mammals that symbolize Australia to be sequenced. The tammar has many unusual biological characteristics, including the longest period of embryonic diapause of any mammal, extremely synchronized seasonal breeding and prolonged and sophisticated lactation within a well-defined pouch. Like other marsupials, it gives birth to highly altricial young, and has a small number of very large chromosomes, making it a valuable model for genomics, reproduction and development.
Results
The genome has been sequenced to 2 × coverage using Sanger sequencing, enhanced with additional next generation sequencing and the integration of extensive physical and linkage maps to build the genome assembly. We also sequenced the tammar transcriptome across many tissues and developmental time points. Our analyses of these data shed light on mammalian reproduction, development and genome evolution: there is innovation in reproductive and lactational genes, rapid evolution of germ cell genes, and incomplete, locus-specific X inactivation. We also observe novel retrotransposons and a highly rearranged major histocompatibility complex, with many class I genes located outside the complex. Novel microRNAs in the tammar HOX clusters uncover new potential mammalian HOX regulatory elements.
Conclusions
Analyses of these resources enhance our understanding of marsupial gene evolution, identify marsupial-specific conserved non-coding elements and critical genes across a range of biological systems, including reproduction, development and immunity, and provide new insight into marsupial and mammalian biology and genome evolution.
doi:10.1186/gb-2011-12-8-r81
PMCID: PMC3277949  PMID: 21854559
7.  MHC gene copy number variation in Tasmanian devils: implications for the spread of a contagious cancer 
Tasmanian devils face extinction owing to the emergence of a contagious cancer. Devil facial tumour disease (DFTD) is a clonal cancer spread owing to a lack of major histocompatibility complex (MHC) barriers in Tasmanian devil populations. We present a comprehensive screen of MHC diversity in devils and identify 25 MHC types and 53 novel sequences, but conclude that overall levels of MHC diversity at the sequence level are low. The majority of MHC Class I variation can be explained by allelic copy number variation with two to seven sequence variants identified per individual. MHC sequences are divided into two distinct groups based on sequence similarity. DFTD cells and most devils have sequences from both groups. Twenty per cent of individuals have a restricted MHC repertoire and contain only group I or only group II sequences. Counterintuitively, we postulate that the immune system of individuals with a restricted MHC repertoire may recognize foreign MHC antigens on the surface of the DFTD cell. The implication of these results for management of DFTD and this endangered species are discussed.
doi:10.1098/rspb.2009.2362
PMCID: PMC2880097  PMID: 20219742
Tasmanian devil; MHC; devil facial tumour disease; marsupial; cancer
8.  MHC-linked and un-linked class I genes in the wallaby 
BMC Genomics  2009;10:310.
Background
MHC class I antigens are encoded by a rapidly evolving gene family comprising classical and non-classical genes that are found in all vertebrates and involved in diverse immune functions. However, there is a fundamental difference between the organization of class I genes in mammals and non-mammals. Non-mammals have a single classical gene responsible for antigen presentation, which is linked to the antigen processing genes, including TAP. This organization allows co-evolution of advantageous class Ia/TAP haplotypes. In contrast, mammals have multiple classical genes within the MHC, which are separated from the antigen processing genes by class III genes. It has been hypothesized that separation of classical class I genes from antigen processing genes in mammals allowed them to duplicate. We investigated this hypothesis by characterizing the class I genes of the tammar wallaby, a model marsupial that has a novel MHC organization, with class I genes located within the MHC and 10 other chromosomal locations.
Results
Sequence analysis of 14 BACs containing 15 class I genes revealed that nine class I genes, including one to three classical class I, are not linked to the MHC but are scattered throughout the genome. Kangaroo Endogenous Retroviruses (KERVs) were identified flanking the MHC un-linked class I. The wallaby MHC contains four non-classical class I, interspersed with antigen processing genes. Clear orthologs of non-classical class I are conserved in distant marsupial lineages.
Conclusion
We demonstrate that classical class I genes are not linked to antigen processing genes in the wallaby and provide evidence that retroviral elements were involved in their movement. The presence of retroviral elements most likely facilitated the formation of recombination hotspots and subsequent diversification of class I genes. The classical class I have moved away from antigen processing genes in eutherian mammals and the wallaby independently, but both lineages appear to have benefited from this loss of linkage by increasing the number of classical genes, perhaps enabling response to a wider range of pathogens. The discovery of non-classical orthologs between distantly related marsupial species is unusual for the rapidly evolving class I genes and may indicate an important marsupial specific function.
doi:10.1186/1471-2164-10-310
PMCID: PMC2719672  PMID: 19602235
9.  Reconstructing an Ancestral Mammalian Immune Supercomplex from a Marsupial Major Histocompatibility Complex 
PLoS Biology  2006;4(3):e46.
The first sequenced marsupial genome promises to reveal unparalleled insights into mammalian evolution. We have used theMonodelphis domestica (gray short-tailed opossum) sequence to construct the first map of a marsupial major histocompatibility complex (MHC). The MHC is the most gene-dense region of the mammalian genome and is critical to immunity and reproductive success. The marsupial MHC bridges the phylogenetic gap between the complex MHC of eutherian mammals and the minimal essential MHC of birds. Here we show that the opossum MHC is gene dense and complex, as in humans, but shares more organizational features with non-mammals. The Class I genes have amplified within the Class II region, resulting in a unique Class I/II region. We present a model of the organization of the MHC in ancestral mammals and its elaboration during mammalian evolution. The opossum genome, together with other extant genomes, reveals the existence of an ancestral “immune supercomplex” that contained genes of both types of natural killer receptors together with antigen processing genes and MHC genes.
Opossum genomic sequence data permit researchers to fill gaps in our knowledge of how the Major Histocompatibility Complex evolved within the mammalian lineage.
doi:10.1371/journal.pbio.0040046
PMCID: PMC1351924  PMID: 16435885
10.  Genome sequence of an Australian kangaroo, Macropus eugenii, provides insight into the evolution of mammalian reproduction and development 
Renfree, Marilyn B | Papenfuss, Anthony T | Deakin, Janine E | Lindsay, James | Heider, Thomas | Belov, Katherine | Rens, Willem | Waters, Paul D | Pharo, Elizabeth A | Shaw, Geoff | Wong, Emily SW | Lefèvre, Christophe M | Nicholas, Kevin R | Kuroki, Yoko | Wakefield, Matthew J | Zenger, Kyall R | Wang, Chenwei | Ferguson-Smith, Malcolm | Nicholas, Frank W | Hickford, Danielle | Yu, Hongshi | Short, Kirsty R | Siddle, Hannah V | Frankenberg, Stephen R | Chew, Keng Y | Menzies, Brandon R | Stringer, Jessica M | Suzuki, Shunsuke | Hore, Timothy A | Delbridge, Margaret L | Patel, Hardip | Mohammadi, Amir | Schneider, Nanette Y | Hu, Yanqiu | O'Hara, William | Al Nadaf, Shafagh | Wu, Chen | Feng, Zhi-Ping | Cocks, Benjamin G | Wang, Jianghui | Flicek, Paul | Searle, Stephen MJ | Fairley, Susan | Beal, Kathryn | Herrero, Javier | Carone, Dawn M | Suzuki, Yutaka | Sugano, Sumio | Toyoda, Atsushi | Sakaki, Yoshiyuki | Kondo, Shinji | Nishida, Yuichiro | Tatsumoto, Shoji | Mandiou, Ion | Hsu, Arthur | McColl, Kaighin A | Lansdell, Benjamin | Weinstock, George | Kuczek, Elizabeth | McGrath, Annette | Wilson, Peter | Men, Artem | Hazar-Rethinam, Mehlika | Hall, Allison | Davis, John | Wood, David | Williams, Sarah | Sundaravadanam, Yogi | Muzny, Donna M | Jhangiani, Shalini N | Lewis, Lora R | Morgan, Margaret B | Okwuonu, Geoffrey O | Ruiz, San J | Santibanez, Jireh | Nazareth, Lynne | Cree, Andrew | Fowler, Gerald | Kovar, Christie L | Dinh, Huyen H | Joshi, Vandita | Jing, Chyn | Lara, Fremiet | Thornton, Rebecca | Chen, Lei | Deng, Jixin | Liu, Yue | Shen, Joshua Y | Song, Xing-Zhi | Edson, Janette | Troon, Carmen | Thomas, Daniel | Stephens, Amber | Yapa, Lankesha | Levchenko, Tanya | Gibbs, Richard A | Cooper, Desmond W | Speed, Terence P | Fujiyama, Asao | M Graves, Jennifer A | O'Neill, Rachel J | Pask, Andrew J | Forrest, Susan M | Worley, Kim C
Genome Biology  2011;12(12):414.
doi:10.1186/gb-2011-12-12-414
PMCID: PMC3334613

Results 1-10 (10)