The Tasmanian devil is threatened with extinction in the wild by devil facial tumour disease (DFTD). Measures to counter extinction include the maintenance of a genetically diverse captive insurance population, and the development of a protective vaccine against DFTD. The success of the captive insurance population has allowed progress to be made on the long-term goal of rewilding and this coincides with promising results obtained from previous immunization trials on captive devils. Consequently the 17 devils ear-marked for release in September 2015 are being used in a more substantial immunization trial.
The immunization trial comprises monthly subcutaneous injections of non-viable modified DFTD cells plus adjuvants. Blood samples are collected fortnightly to assess humoral and cell mediated immune responses.
The previous immunization trials resulted in antibody responses from all 4 captive devils as demonstrated via flow cytometry and ELISA. The cell-mediated immune responses were more difficult to demonstrate but there was evidence of killing of DFTD cells by peripheral blood lymphocytes in some of the cytotoxicity assays. Supernatants of the assays were collected and frozen with the expectation that an interferon gamma detection ELISA will be developed.
The same methods are being used to assess the responses of the 17 devils due for release. This trial started on 09/02/15 and preliminary results will be available in May 2015. After release, the devils will be monitored regularly to assess their adaptation to the wild, their on-going immune responses to DFTD, and if/ when they succumb to DFTD.
The primary purpose of immunizing these devils is to provide a large enough sample size for the immunization trial to enable a robust assessment of responses detected. It is hoped the immunizations will also provide some protection against any natural DFTD challenge these devils might face once released and thus mitigate this threat.