Threats: Devil Facial Tumour Disease (DFTD)
General Threats:
The Tasmanian Devils were originally hunted and killed by the European settlers in the 18th and early 19th century, because they thought that the Devils would eat their animals on their farms. The population decreased rapidly until in 1941 when the Devils became protected by the law.
There became some hope for the Devils, and gradually the population increased without the settlers trapping them. But now a more serious new threat has emerged: Devil Facial Tumour Disease (DFTD), and this is threatening them with extinction. DFTD is a serious cancer which kills devils six months from the time they contract the disease. This cancer was initially discovered in 1996 in the north-east region of Tasmania. Since then it has spread and scientists think as much as 60% of the state could be infected.
In 2009 the Tasmanian Devil were recognised as Endangered, after the Devil population declined by more than 90%. The average of Tasmanian Devils seen reduced by approximately 95%. Other threats to the Tasmanian Devils include becoming road kill, getting devoured by dogs and foxes, but the main threat is still the DFTD. The trend of the Devil population is decreasing. Scientists think in as little as 40 years' time Tasmanian Devils could be completely wiped out by this disease, if it is not treated or if the Tasmanian Devils are not put into a breeding program.
The Tasmanian Devils were originally hunted and killed by the European settlers in the 18th and early 19th century, because they thought that the Devils would eat their animals on their farms. The population decreased rapidly until in 1941 when the Devils became protected by the law.
There became some hope for the Devils, and gradually the population increased without the settlers trapping them. But now a more serious new threat has emerged: Devil Facial Tumour Disease (DFTD), and this is threatening them with extinction. DFTD is a serious cancer which kills devils six months from the time they contract the disease. This cancer was initially discovered in 1996 in the north-east region of Tasmania. Since then it has spread and scientists think as much as 60% of the state could be infected.
In 2009 the Tasmanian Devil were recognised as Endangered, after the Devil population declined by more than 90%. The average of Tasmanian Devils seen reduced by approximately 95%. Other threats to the Tasmanian Devils include becoming road kill, getting devoured by dogs and foxes, but the main threat is still the DFTD. The trend of the Devil population is decreasing. Scientists think in as little as 40 years' time Tasmanian Devils could be completely wiped out by this disease, if it is not treated or if the Tasmanian Devils are not put into a breeding program.
What is Devil Facial Tumour Disease?
Devil Facial Tumour Disease is a term used to describe a catastrophic condition in Tasmanian devils, symptoms of the disease showing in obvious facial tumours.
The Devil Facial Tumour Disease is a transmittable cancer, a virus only able to survive in the population of the Tasmanian devil. The virus that causes the cancer is passed onto each Tasmanian devil through, biting, mating and breeding, or through the saliva of the Devil. The journey of the cancer cell is difficult to avoid, as it is a natural instinct for all Tasmanian Devils to bite and fight over food, mates, and breeding ground. When a Tasmanian Devil gets this disease, it will certainly face death, as the disease takes its toll to lead to a death due to lack of food, water, and lack of bodily functions.
What are the characteristics of the DFTD?
Once a Devil has the disease, it will begin to take its effect after a few, short months. Signs will begin to appear in or around the mouth, usually in small lesions, or pimple like bumps. These miniscule disfigurements will then rapidly expand to become extensive tumours, which grossly distort the face and neck and sometimes other areas. The devils will then find it extremely difficult to eat and drink, leading then to death from starvation, dehydration and the breakdown of body functions, usually within three months of the first appearance of the lesions or bumps. In the later stages of the disease, the cancer will typically take over vital organs such as the lungs, heart and brain.
Devil Facial Tumour Disease is a term used to describe a catastrophic condition in Tasmanian devils, symptoms of the disease showing in obvious facial tumours.
The Devil Facial Tumour Disease is a transmittable cancer, a virus only able to survive in the population of the Tasmanian devil. The virus that causes the cancer is passed onto each Tasmanian devil through, biting, mating and breeding, or through the saliva of the Devil. The journey of the cancer cell is difficult to avoid, as it is a natural instinct for all Tasmanian Devils to bite and fight over food, mates, and breeding ground. When a Tasmanian Devil gets this disease, it will certainly face death, as the disease takes its toll to lead to a death due to lack of food, water, and lack of bodily functions.
What are the characteristics of the DFTD?
Once a Devil has the disease, it will begin to take its effect after a few, short months. Signs will begin to appear in or around the mouth, usually in small lesions, or pimple like bumps. These miniscule disfigurements will then rapidly expand to become extensive tumours, which grossly distort the face and neck and sometimes other areas. The devils will then find it extremely difficult to eat and drink, leading then to death from starvation, dehydration and the breakdown of body functions, usually within three months of the first appearance of the lesions or bumps. In the later stages of the disease, the cancer will typically take over vital organs such as the lungs, heart and brain.
What is unusual about this disease, and can other animals be affected by it?
The DFTD is unusual in several ways. Firstly, it is a cancer. Cancers as we know it are not transmittable, and they cannot be passed on in any way. Viruses can though, and they are usually spread through bodily fluids. The DFTD has both characteristics, which make it tricky to fight. The DFTD is also extremely rare, because it is one of the only three contagious cancers ever recorded.
Also, when an animal like the Tasmanian Devil can pass a cancer cell as easily as the DFTD, other species sharing similar characteristics usually get it. However, the DFTD, is found to only reside in Tasmanian Devils.
The virus would not be able to survive or multiply in any other animal because their immune system would immediately recognise the cell as harmful, and banish or harm the living cell before it does any damage to the body of the animal.
If it is a virus, why can’t the immune system react to it?
After the Tasmanian Devils received the cancer, questions were raised as to why the immune system didn’t recognise the cancer cells like any other animal immune system presented with the cells.
Scientists further investigated as to whether or not the Tasmanian Devil had the correct genes to allow the immune system to recognise and banish the foreign cancer cells. They did this by mixing the lymphocytes (the key cell in the immune system) from many different Devils from all over Tasmania, to see if the cells reacted to each other. The results showed that Tasmanian Devils failed to differentiate the cells from other Devils from their own. This conclusion pointed to the fact that the scarcity of genetic diversity of the Tasmanian devils contributed greatly to the cancer cell being able to travel undetected by the immune system through healthier devils, and allowing the cancer to become contagious. When a Devil receives the cancer cell, the lack of genetic diversity accept the cancer cells as its own, and therefore fail to reject them, allowing the cancer to take hold of the devil entirely with months.
However, there is another component of the virus that helps it pass by the immune system of a Tasmanian Devil without getting detected. It down regulates MHC cells, so that antigens are not shown to the immune system, therefore letting them thrive in the body of the Tasmanian Devil.
The DFTD is unusual in several ways. Firstly, it is a cancer. Cancers as we know it are not transmittable, and they cannot be passed on in any way. Viruses can though, and they are usually spread through bodily fluids. The DFTD has both characteristics, which make it tricky to fight. The DFTD is also extremely rare, because it is one of the only three contagious cancers ever recorded.
Also, when an animal like the Tasmanian Devil can pass a cancer cell as easily as the DFTD, other species sharing similar characteristics usually get it. However, the DFTD, is found to only reside in Tasmanian Devils.
The virus would not be able to survive or multiply in any other animal because their immune system would immediately recognise the cell as harmful, and banish or harm the living cell before it does any damage to the body of the animal.
If it is a virus, why can’t the immune system react to it?
After the Tasmanian Devils received the cancer, questions were raised as to why the immune system didn’t recognise the cancer cells like any other animal immune system presented with the cells.
Scientists further investigated as to whether or not the Tasmanian Devil had the correct genes to allow the immune system to recognise and banish the foreign cancer cells. They did this by mixing the lymphocytes (the key cell in the immune system) from many different Devils from all over Tasmania, to see if the cells reacted to each other. The results showed that Tasmanian Devils failed to differentiate the cells from other Devils from their own. This conclusion pointed to the fact that the scarcity of genetic diversity of the Tasmanian devils contributed greatly to the cancer cell being able to travel undetected by the immune system through healthier devils, and allowing the cancer to become contagious. When a Devil receives the cancer cell, the lack of genetic diversity accept the cancer cells as its own, and therefore fail to reject them, allowing the cancer to take hold of the devil entirely with months.
However, there is another component of the virus that helps it pass by the immune system of a Tasmanian Devil without getting detected. It down regulates MHC cells, so that antigens are not shown to the immune system, therefore letting them thrive in the body of the Tasmanian Devil.
What are MHC molecules?
Major histocompatibility complex or MHC molecules, are a group of genes that cipher for proteins found on the surface of a cell that guide the immune system to perceive any unfamiliar substances. MHC cells are found in all complex vertebrates. In human beings, the MHC cells are also named human leukocyte antigen (HLA) system.
There are two major types of MHC molecules, sorted into two classes, class I and class II. Class I molecules span the membrane of almost every cell of any living, multicellular organism. However, class II molecules are confined to the cells of the immune system, named macrophages and lymphocytes.
MHC molecules are incredibly important factor of the immune system as they allow for the T lymphocytes to detect cells such as macrophages that could have consumed virulent micro-organisms.
When a macrophage consumes a micro-organism, it partially digests it. It then presents peptide fragments (or antigens) of the micro-organism on the membrane of its cell, bound to MHC molecules. The T lymphocyte should recognise the foreign substance secured to the MHC molecule, and attaches to it, then stimulating an immune response. In uninfected cells, the MHC molecule will just present a sample of peptide from its own cell, which the lymphocyte will recognise as ‘self’ and not react to.
MHC molecules help the immune system recognise any substance by presenting small fragments of the molecule, known as antigens, on the surface of the cell.
These molecules indicate to the immune system whether or not it is ‘self’ (one of their own cells), or ‘non-self’ (a foreign substance). After studying the cancer cell, it was found that the genes required to stimulate the MHC molecules to be expressed on the surface of the cell had been abolished.
It has been established from these conclusions that the tumour has evolved a way to hide from the immune system of the Tasmanian Devils. The cell down regulates the MHC, tricking the immune system into thinking that it is a ‘self’ cell, as it is not presenting any tumour antigens for the immune system to analyse.
Conclusion:
The virus dampens the ability of the MHC cells in helping the immune system recognise any foreign substances.
Major histocompatibility complex or MHC molecules, are a group of genes that cipher for proteins found on the surface of a cell that guide the immune system to perceive any unfamiliar substances. MHC cells are found in all complex vertebrates. In human beings, the MHC cells are also named human leukocyte antigen (HLA) system.
There are two major types of MHC molecules, sorted into two classes, class I and class II. Class I molecules span the membrane of almost every cell of any living, multicellular organism. However, class II molecules are confined to the cells of the immune system, named macrophages and lymphocytes.
MHC molecules are incredibly important factor of the immune system as they allow for the T lymphocytes to detect cells such as macrophages that could have consumed virulent micro-organisms.
When a macrophage consumes a micro-organism, it partially digests it. It then presents peptide fragments (or antigens) of the micro-organism on the membrane of its cell, bound to MHC molecules. The T lymphocyte should recognise the foreign substance secured to the MHC molecule, and attaches to it, then stimulating an immune response. In uninfected cells, the MHC molecule will just present a sample of peptide from its own cell, which the lymphocyte will recognise as ‘self’ and not react to.
MHC molecules help the immune system recognise any substance by presenting small fragments of the molecule, known as antigens, on the surface of the cell.
These molecules indicate to the immune system whether or not it is ‘self’ (one of their own cells), or ‘non-self’ (a foreign substance). After studying the cancer cell, it was found that the genes required to stimulate the MHC molecules to be expressed on the surface of the cell had been abolished.
It has been established from these conclusions that the tumour has evolved a way to hide from the immune system of the Tasmanian Devils. The cell down regulates the MHC, tricking the immune system into thinking that it is a ‘self’ cell, as it is not presenting any tumour antigens for the immune system to analyse.
Conclusion:
The virus dampens the ability of the MHC cells in helping the immune system recognise any foreign substances.