A human adenovirus encoding IFN-γ can transduce Tasmanian devil facial tumour cells and upregulate MHC-I.

The devil facial tumour disease (DFTD) has led to a massive decline in the wild Tasmanian devil (Sarcophilus harrisii) population. The disease is caused by two independent devil facial tumours (DFT1 and DFT2). These transmissible cancers have a mortality rate of nearly 100 %. An adenoviral vector-based vaccine has been proposed as a conservation strategy for the Tasmanian devil. This study aimed to determine if a human adenovirus serotype 5 could express functional transgenes in devil cells. As DFT1 cells do not constitutively express major histocompatibility complex class I (MHC-I), we developed a replication-deficient adenoviral vector that encodes devil interferon gamma (IFN-γ) fused to a fluorescent protein reporter. Our results show that adenoviral-expressed IFN-γ was able to stimulate upregulation of beta-2 microglobulin, a component of MHC-I, on DFT1, DFT2 and devil fibroblast cell lines. This work suggests that human adenoviruses can serve as a vaccine platform for devils and potentially other marsupials.

An oral bait vaccination approach for the Tasmanian devil facial tumor diseases.

Introduction: The Tasmanian devil (Sarcophilus harrisii) is the largest extant carnivorous marsupial. Since 1996, its population has declined by 77% primarily due to a clonal transmissible tumor, known as devil facial tumor (DFT1) disease. In 2014, a second transmissible devil facial tumor (DFT2) was discovered. DFT1 and DFT2 are nearly 100% fatal.Areas covered: We review DFT control approaches and propose a rabies-style oral bait vaccine (OBV) platform for DFTs. This approach has an extensive safety record and was a primary tool in large-scale rabies virus elimination from wild carnivores across diverse landscapes. Like rabies virus, DFTs are transmitted by oral contact, so immunizing the oral cavity and stimulating resident memory cells could be advantageous. Additionally, exposing infected devils that already have tumors to OBVs could serve as an oncolytic virus immunotherapy. The primary challenges may be identifying appropriate DFT-specific antigens and optimization of field delivery methods.Expert opinion: DFT2 is currently found on a peninsula in southern Tasmania, so an OBV that could eliminate DFT2 should be the priority for this vaccine approach. Translation of an OBV approach to control DFTs will be challenging, but the approach is feasible for combatting ongoing and future disease threats.

Evaluation of Oral Bait Vaccine Efficacy Against Classical Swine Fever in Village Backyard Pig Farms in Bhutan.

Control and eradication of classical swine fever (CSF) in countries with a high proportion of backyard holdings is a challenge. Conventional attenuated Chinese C-strain vaccines, though safe and effective, are difficult to use in backyard farms due to various practical reasons. The aim of this study was to evaluate the efficacy of the CSF oral bait vaccine in village backyard pig farms and to assess the farmers' knowledge on CSF and motivation on using oral vaccines. The pigs were fed the bait by the farmers themselves; one bait was given on day 0, followed by second bait on the next day. Seventy-three per cent (140 of 193 pigs) of vaccinated pigs had either a slight (2-fold-3-fold; 60 pigs) or significant (at least 4-fold; 80 pigs) increase of the antibody titre against CSFV. A significant increase of the antibody titres was mainly observed in pigs with no pre-vaccination titre (OR = 12, 95% CI = 4-40). The number of pigs with protective antibody titres (≥40) rose from 47 (24%) to 115 (60%) following vaccination. Only 30% of the farmers claimed to be familiar with CSF, although clinical signs they mentioned were rather unspecific and could relate to many other pig diseases. Most of the farmers claimed to be motivated to use oral vaccines if made available. The oral vaccine could be a substitute for the conventional attenuated CSF vaccines in areas where it is logistically difficult for veterinarians to visit. It may therefore be a useful tool to combat endemic CSF disease in regions where the disease continues to have a serious impact on the backyard farmers who depend on pig farming for their sustenance and livelihoods.