Demonstration of immune responses against devil facial tumour disease in wild Tasmanian devils.

Ruth Pye,Menna E Jones,Alison Caldwell,Rodrigo Hamede,Graeme W Knowles,Alexandre Kreiss,A Bruce Lyons,Hannah V Siddle,Kate Swift,Gregory M Woods

doi:10.1098/rsbl.2016.0553

Abstract

Devil facial tumour disease (DFTD) is a recently emerged fatal transmissible cancer decimating the wild population of Tasmanian devils (Sarcophilus harrisii). Biting transmits the cancer cells and the tumour develops in the new host as an allograft. The literature reports that immune escape mechanisms employed by DFTD inevitably result in host death. Here we present the first evidence that DFTD regression can occur and that wild devils can mount an immune response against the disease. Of the 52 devils tested, six had serum antibodies against DFTD cells and, in one case, prominent T lymphocyte infiltration in its tumour. Notably, four of the six devils with serum antibody had histories of DFTD regression. The novel demonstration of an immune response against DFTD in wild Tasmanian devils suggests that a proportion of wild devils can produce a protective immune response against naturally acquired DFTD. This has implications for tumour–host coevolution and vaccine development.

Highlights

The Tasmanian devil is the world’s largest carnivorous marsupial and unique to Tasmania, the island state of Australia
Serum antibodies persisted in TD3 at this time and tumour-infiltrating MHC-II positive cells and CD3 positive T lymphocytes were present in the biopsy
While anti-DFT1 immune responses have been induced in captive devils by immunizing with killed DFT1 cell preparations [10], no convincing evidence for immune responses against DFT1 have previously been identified in wild devils

Summary

Introduction

The Tasmanian devil is the world’s largest carnivorous marsupial and unique to Tasmania, the island state of Australia. The species is listed as Endangered owing to mortality from devil facial tumour disease (DFTD) [1]. The disease is a transmissible cancer, first observed in 1996 in the far northeast of the state It is found throughout the majority of the devil’s geographical range [2]. In 2015, a second transmissible facial cancer was reported in Tasmanian devils in the southeast of the state [4]. The disease is transmitted as an allograft [5] and three explanations were initially suggested to explain the lack of immune rejection: the limited genetic diversity of the species; the unknown competency of the devil’s immune system; and the immune evasion mechanisms of the tumour [2]. All research to date addressing these possibilities suggests that it is the successful immune evasion strategies

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Conclusion