Wednesday, March 13, 2013

New findings on how devil facial tumour disease (DFTD) evades the immune system give hope for a potential vaccine.

The Tasmanian devil population is being decimated by a contagious form of cancer. Devils catch the cancer when bitten by an infected devil, causing them to develop facial tumours. These tumours either become so large that the devil cannot eat and drink or they metastasize, spreading to other organs. Since its emergence in 1996, it's estimated DFTD has reduced the devil population by 60% and will drive the species extinct within 20-30 years.

Scientists have long been puzzled by how DFTD escapes the detection of the immune system. Usually the immune system identifies foreign cells using surface proteins called major histocompatibility complexes (MHC). Researchers assumed that, due to devils' low genetic diversity, the immune system didn't recognise the MHCs of tumour cells as foreign.

But new research reveals they are invisible to the immune system for a different reason - tumour cells don't have MHCs at all. The genes that code for MHCs are still present, but have been "switched off".

The good news is that these genes can be turned back on to produce MHCs, as evidenced by lab work. Tumour biopsies also indicate that if this happens spontaneously, the devil's immune system attacks the tumours (though ultimately fails to save the devil). The plan is to develop a vaccine using tumour cells with MHCs, and to administer this to healthy devils. However, this vaccine may be some time away.

"Developing a vaccine based on our research could tip the balance in the favor of the devil and give them a fighting chance,” said lead author Dr. Hannah Siddle (University of Cambridge, UK). “However, we still face some hurdles. The tumor is evolving over time and any vaccine program would have to take this into consideration. Also, because of the difficulties of vaccinating a wild population, it may be more efficient to use a vaccine in the context of returning captive devils to the wild.”

To read the paper: http://bit.ly/13VRg1N

Photo: Tasmanian devil with facial tumours. These tumours get progressively larger and more severe with time (credit to Rodrigue Hamende).

http://www.nature.com/news/vaccine-hope-for-tasmanian-devil-tumour-disease-1.12576

http://www.livescience.com/27804-contagious-devil-tumor-disease.html

http://www.redorbit.com/news/science/1112801177/new-hope-for-a-cure-to-tasmanian-devil-cancer-031213/

http://www.eurekalert.org/pub_releases/2013-03/uoc-hft031113.php
New findings on how devil facial tumour disease (DFTD) evades the immune system give hope for a potential vaccine.

The Tasmanian devil population is being decimated by a contagious form of cancer. Devils catch the cancer when bitten by an infected devil, causing them to develop facial tumours. These tumours either become so large that the devil cannot eat and drink or they metastasize, spreading to other organs. Since its emergence in 1996, it's estimated DFTD has reduced the devil population by 60% and will drive the species extinct within 20-30 years. 

Scientists have long been puzzled by how DFTD escapes the detection of the immune system. Usually the immune system identifies foreign cells using surface proteins called major histocompatibility complexes (MHC). Researchers assumed that, due to devils' low genetic diversity, the immune system didn't recognise the MHCs of tumour cells as foreign.

But new research reveals they are invisible to the immune system for a different reason - tumour cells don't have MHCs at all. The genes that code for MHCs are still present, but have been "switched off".

The good news is that these genes can be turned back on to produce MHCs, as evidenced by lab work. Tumour biopsies also indicate that if this happens spontaneously, the devil's immune system attacks the tumours (though ultimately fails to save the devil). The plan is to develop a vaccine using tumour cells with MHCs, and to administer this to healthy devils. However, this vaccine may be some time away.

"Developing a vaccine based on our research could tip the balance in the favor of the devil and give them a fighting chance,” said lead author Dr. Hannah Siddle (University of Cambridge, UK). “However, we still face some hurdles. The tumor is evolving over time and any vaccine program would have to take this into consideration. Also, because of the difficulties of vaccinating a wild population, it may be more efficient to use a vaccine in the context of returning captive devils to the wild.”

To read the paper: http://bit.ly/13VRg1N

Photo: Tasmanian devil with facial tumours. These tumours get progressively larger and more severe with time (credit to Rodrigue Hamende).

http://www.nature.com/news/vaccine-hope-for-tasmanian-devil-tumour-disease-1.12576

http://www.livescience.com/27804-contagious-devil-tumor-disease.html

http://www.redorbit.com/news/science/1112801177/new-hope-for-a-cure-to-tasmanian-devil-cancer-031213/

http://www.eurekalert.org/pub_releases/2013-03/uoc-hft031113.php

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