The equine sarcoid : molecular and epidemiological studies in Equus asinus
The aim of this project was to investigate some aspects of the equine sarcoid of the donkey (Equus asinus). The study was undertaken in a large population of animals located at The Donkey Sanctuary, Sidford, Devon, in order to assess the feasibility of eventual vaccination against the disease. All material was derived from clinical cases and no animal experimentation was involved in the investigation. The epidemiological studies were based upon information exported from the clinical records maintained on The Donkey Sanctuary mainframe computer. Of those donkeys developing sarcoids at The Sanctuary, the sex, age, age at which the animal entered The Sanctuary and the duration of stay were all shown to be factors affecting the likelihood of an individual donkey having sarcoids. In general, the disease was most likely to affect young male donkeys within the first four years at The Sanctuary and the tumours were most frequently observed in the paragenital region. A general linear model was constructed and it was demonstrated that male donkeys were, at best 1.1 times and, at worst 4.5 times more likely to have sarcoids than females. The disease model was then used as a management tool for the indentification of animals at the highest risk of developing sarcoids, in order to effect more prompt therapeutic intervention. The serological status of donkeys at The Sanctuary was investigated by the immunoblot assay of sera from sarcoid-affected and clinically-normal donkeys for the presence of antibody to disrupted bovine papillomavirus type 2 (BPV-2) virion and to the L1 open reading frame (ORF) encoded fusion protein. Antibody to the antigenic targets was demonstrated in 86 per cent of donkeys in the case of the L1 fusion protein and 96 per cent of donkeys in the case of disrupted virion; there was no correlation between the presence of antibody and clinical status. The antibody detected by immunoblot was unable to neutralise the transforming activity of BPV-2 in vitro.