LADoc00

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This is crazy:

Devil facial tumour disease (DFTD) is a fatal disease of the Tasmanian Devil. First seen in 1999, the disease has ravaged Tasmania's wild devils, and estimates of the impact range from 20% to as much as a 50% decline in the devil population with over 65% of the State affected.[1][2] Affected high-density populations suffer up to 100% mortality in 12–18 months.[3] The disease has mainly been concentrated in the State’s eastern half, although in early 2005, three cases were confirmed in South Tasmania.[citation needed]

DFTD begins as lesions and lumps around the mouth. The lesions and lumps develop into cancerous tumours that spread from the face to the entire body. The tumours interfere with feeding, and the affected animal may starve to death.

Using cultures of the cancerous tissue to study the condition, researchers have identified the cancer as neuroendocrine in nature, and all cancer cells have identical chromosomal rearrangements.[4] A virus was initially thought to be the cause of DFTD, but no evidence of such a virus could be detected in the cancer cells. The cancer cells themselves are an infective agent, with transmission of the disease occurring by biting, feeding on the same material, and aggressive mating. Final confirmation of this came when researcher Anne-Maree Pearse and colleagues found an infected animal that had a chromosomal abnormality in its non-tumourous cells that did not appear in its tumour cells, proving that the tumour cells could not be descended from the animal's own cells

 

djmd

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yaah said:
Is that from the Weekly World News? It sounds a bit odd.

It at least possible. Think about transplant organs containing neoplasia.
I would wonder if the neoplastic cell can "infect" any T.Devil, or if it has HLA limits? I wonder how much immuno-variation there is between T.Devils?
Maybe the tumor is very primiative and manages to express almost no antigen-profile?
 
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Matte Kudesai

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djmd said:
It at least possible. Think about transplant organs containing neoplasia.
I would wonder if the neoplastic cell can "infect" any T.Devil, or if it has HLA limits? I wonder how much immuno-variation there is between T.Devils?
Maybe the tumor is very primiative and manages to express almost no antigen-profile?
I think a recent nature paper also reported that it could be due to... "low genetic diversity and high degree of kinship among devils might help to reduce their immune response to implanted cancer cells."


Allograft theory: transmission of devil facial-tumour disease.
Pearse AM, Swift K.
[size=-1]Nature. 2006 Feb 2;439(7076):549.
PMID: 16452970
[/size]
 

djmd

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Aubrey said:
It could even be prion-based. Funky funky.
LADoc00 said:
an infected animal that had a chromosomal abnormality in its non-tumourous cells that did not appear in its tumour cells, proving that the tumour cells could not be descended from the animal's own cells
That aint no Prion!

Matte Kudesai's article link is what I was talking about.

Those cancer cells really did figure out a path to immortality... (till they kill the last T.Devil.)
:smuggrin:
 

RyMcQ

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The easiest unknown at our yearly vet path resident conference was canine transmissible verereal tumor.

Not that we had any practical experience with it, but it is such an oddball entity that it was always included in the unknowns.
 

Cabbage Head

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Matte Kudesai said:
"low genetic diversity and high degree of kinship among devils might help to reduce their immune response to implanted cancer cells."

High degree of kinship. Heheh.
 

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All the world's troubles can be traced to aggressive mating.
 
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LADoc00

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Contagious Canine Cancer Spread by Parasites Charles Q. Choi
Special to LiveScience
LiveScience.com
2 hours, 35 minutes ago



Dogs have a form of sexually transmitted cancer that for 200 to 2,500 years has apparently spread via contagious tumor cells that escaped from their original body and now travel around the world as parasites.


These cells are the oldest cancers known to science thus far, and could shed light on how cancers survive and evade the immune system.


The researchers investigated canine transmissible venereal tumor, a cancer found in the domestic dog and potentially in relatives such as the gray wolf and coyote. It is spread through sex and licking, biting and sniffing cancerous areas. The tumors usually regress three to nine months after their appearance, leaving the dogs immune to reinfection, although providing enough time for dogs to pass the disease on.


Some human cancers, such as cervical cancer, are caused by viruses.


What is unique about this dog cancer is that, for 30 years, scientists have suggested it was caused by spreading the tumor cells themselves rather than a virus or other contagious agent. Prior research showed, for instance, the disease could not spread from tumor cell extracts or dead tumor cells, but only via living tumor cells. Still, virus-like particles seen in the tumor cells clouded the issue.


Cancer researcher Robin Weiss at University College London and his colleagues analyzed genetic markers in recently collected and archived tissue from dogs spanning five continents, from locales in Italy, India, Kenya, Brazil, the United States, Turkey and Spain. They found the tumor cells did not actually belong to the dogs they were in. Rather, the cells were all genetically nearly identical, apparently stemming from a wolf or a closely related ancient dog breed from China or Siberia.


The tumor cells themselves act as parasites, the new study concludes.


The researchers found the cancer secretes compounds that inhibit facets of the immune systems of their hosts, allowing them to avoid detection. At the same time, the immune inhibition they cause rarely results in death of the infected animal, to help guarantee the host passes the disease on.


Judging by the number of mutations the cancer's DNA accumulated, the researchers estimate it emerged 200 to 2,500 years ago. Instead of becoming progressively more genetically unstable over time, as scientists widely supposed happens to cancer, these cancer cells "do not go on getting more and more genetically unstable," Weiss told LiveScience.


The study is detailed in the Aug. 11 issue of the journal Cell.
 
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