Devil vaccine a step closer

Greg Woods and Bruce Lyons.

Greg Woods and Bruce Lyons.

The results of an international study published recently in Scientific Reports has confirmed the fatal facial tumour disease that has decimated populations of Tasmanian devils in the wild for over 20 years, can be cured using immunotherapy.

Led by the University of Tasmania’s Menzies Institute for Medical Research, the study involved scientists from the Universities of Sydney, Southampton, Southern Denmark and Cambridge, as well as those from UTAS’s School of Medicine, the Walter and Eliza Hall Institute of Medical Research, and CSL Ltd.

The aim of the study was to ‘explore immunisation protocols to enhance protective responses against DFTD’, but due to devils’ endangered status, only a limited number of animals are available for research purposes. This five-year trial, that tested four immunisation protocols sequentially, was therefore restricted to nine healthy and genetically different animals, some of which had reached an advanced age. Continue reading Devil vaccine a step closer

Reduced effect of Tasmanian devil facial tumour disease at the disease front

Pathogen-driven declines in animal populations are increasingly regarded as a major conservation issue. The Tasmanian devil (Sarcophilus harrisii) is threatened with extinction by devil facial tumor disease, a unique transmissible cancer.

The disease is transmitted through direct transfer of tumor cells, which is possible because the genetic diversity of Tasmanian devils is low, particularly in the major histocompatibility complex genes of the immune system.

The far northwest of Tasmania now holds the last remaining disease-free wild devil populations. The recent discovery of unique major histocompatibility complex genotypes in the northwestern region of Tasmania has raised the possibility that some animals may be resilient to the disease. The authors examined the differences in the epidemiology and population effects of devil facial tumor disease at 3 well-studied affected sites in eastern Tasmania and 1 in western Tasmania (West Pencil Pine). Continue reading Reduced effect of Tasmanian devil facial tumour disease at the disease front

OJD on the rise in Tasmania

Picture: Peter Shanks.Spring is the time of year when many rural properties and paddocks in Tasmania are filled with the sight of newborn and frolicking lambs bleating for their mothers among expanding flocks, but in the aftermath of two wet winters Bruce Jackson, senior vet at the Department of Primary Industries, Parks, Water and Environment, recently issued a warning to the state’s farmers and vets confirming the incidence of Ovine Johnes Disease is on the rise.

From Tasmania’s first diagnosed case in 2001, OJD has continued to spread across the state, but reports have suggested there has been a significantly greater prevalence of the disease during the past five years. It is estimated approximately seven per cent of flocks are now affected, although the actual figure could be as high as 35 per cent according to Jackson, who said an important factor in disease control is open and honest communication between neighbouring producers, as well as a proactive vaccination program. Continue reading OJD on the rise in Tasmania

Allorecognition in the Tasmanian devil (Sarcophilus harrisii), an endangered marsupial species with limited genetic diversity

Tasmanian devils (Sarcophilus harrisii) are on the verge of extinction due to a transmissible cancer, devil facial tumour disease (DFTD).

This tumour is an allograft that is transmitted between individuals without immune recognition of the tumour cells. The mechanism to explain this lack of immune recognition and acceptance is not well understood. It has been hypothesized that lack . . . → Read More: Allorecognition in the Tasmanian devil (Sarcophilus harrisii), an endangered marsupial species with limited genetic diversity

Transmissible cancers in dogs and Tasmanian devils

Figure 1.

The Tasmanian devil, the world’s largest marsupial carnivore, is facing possible extinction in the wild due to a transmissible facial cancer known as Tasmanian devil facial tumour disease (DFTD) (Figure 1). DFTD is spread when living cancer cells are spread between animals by biting. In DFTD, the living cancer cell itself is the infectious agent of disease and it remains unclear why these cancer cells are not detected and rejected by the devil’s immune system. The distressing plight of the Tasmanian devil has drawn attention to the existence of transmissible cancers, parasitic cancers spread by the transfer of living cancer cells between hosts. However, it remains a surprisingly little-known fact that the only other transmissible cancer that bears any resemblance to DFTD is a dog cancer that is right under our noses here in Australia.

Canine transmissible venereal tumour (CTVT) is one of the world’s most remarkable cancers. It is a transmissible cancer that affects dogs worldwide. Usually spread during coitus, the disease is most prevalent in areas with large numbers of free-roaming sexually active dogs. The tumour affects both male and female animals, and appears to affect dogs of any breed. CTVT generally manifests itself in the appearance of tumours in and around the genital area, often at the base of the penis in males and in the vulva of females. Starting as small shiny pink/grey lesions, the tumours can progress to become very large and multi-lobulated (Figure 2). The tumour may aggressively invade surrounding tissues and become ulcerated and secondarily infected. However, a combination of surgical debulking and chemotherapy (using vincristine) is often curative.

Figure 2

Genetic studies have provided strong evidence that CTVT is in fact one living cancer cell line that has spread worldwide with dogs. Thus all CTVT tumours are derived from a single original tumour that arose once and has been transmitted through the dog population as a clone. The tumour itself bears closest genetic resemblance to wolves, suggesting that this tumour may have first arisen in a wolf before hitch-hiking its way into dogs through sexual contact. Genetic evidence suggests that the tumour may in fact be quite old, and that the original wolf that gave rise to the tumour may have even lived thousands of years ago. CTVT is by far the oldest known continuously growing cancer in the world. Continue reading Transmissible cancers in dogs and Tasmanian devils