By ERICA REX

They’re inky black, pointy-eared, furry and, in a fierce sort of way, cute. And in May of this year, they were added to Australia’s endangered species list.

Ordinarily solitary, Tasmanian devils commune only to feast on dead animals and to mate in short-lived passionate couplings during which they tear each other apart. Their cries have evoked satanic visions.

Since 1996, a deadly cancer, devil facial tumor disease, has preyed on the devil. Its population has plummeted to fewer than 50,000 from about 150,000, said Dr. Hamish McCallum, senior scientist with the Devil Facial Tumour Disease Program at the University of Tasmania.

Saving the devil from extinction has become a conservation imperative. According to Dr. McCallum, without major intervention, the devil will be extinct in five years.

The devils’ situation is dire. Yet as more has been learned about the disease, hope has appeared. Scientists have begun an experimental inoculation program, and this year, Dr. Greg Woods, an associate professor of immunology at Menzies Research Institute in Hobart, Tasmania’s capital, identified one devil able to mount an antibody response to the tumor.

The devil, Cedric, is a 3-year-old male from western Tasmania who has been living in captivity for several months. Dr. Woods inoculated Cedric and his halfbrother, Clinky, who was also diseasefree at the time, with irradiated - that is, dead - devil tumor cells. Although they had the same mother, Cedric and Clinky had different fathers.

He then administered live tumor cells to both. Cedric mounted an immune response and lived. Clinky did not develop an immune response, and he succumbed to the cancer. His father’s genetics made Clinky’s immune system more like that of the devils found in eastern Tasmania.

All mammalian immune systems rely on certain cells to recognize invaders. Demarcation of “otherness” at the cellular level is carried out in a part of the mammalian genome called the major histocompatibility complex, or M.H.C. An animal’s ability to fight off disease depends on this group of genes.

“The tumor has no foreign cell surface markers,” said Dr.
Katherine Belov, a scientist in the Australasian Wildlife Genomics Group at the University of Sydney.“If tumor cells get into a devil, its own immune system should be able to see the cells as foreign.
That doesn’t happen because the tumor’s cells look like devils’ own cells.”

Not recognizing a foreign cell, the immune system does not create antibodies.

This cancer, Dr. Woods and his colleagues found, was unlike any the researchers had seen before.

“In all other cancers, what you’ve got is your own cells gone haywire, whereas in this particular cancer, the cells are not from the host, they’re from a different animal,” Dr. McCallum said.“The tumor itself is the infectious agent.”

The tumor plaguing the devil is a clone. When animals bite each other in the face, as they do during mating season, tumor cells are passed from host to host.

Dr. Woods said he would begin the search for naturally resistant devils early next year. He posits that the devils’ best bet lies within its own genome.