Screening for bovine papillomavirus in peripheral blood cells of donkeys with and without sarcoids

Papillomaviral DNA has been identified in peripheral blood cells of both cattle and humans with and without associated disease and it has been suggested that such cells may act as sites of viral latency. In order to investigate the possibility of latent papillomaviral infection in the aetiopathogenesis of the equine sarcoid, peripheral blood derived DNA samples from 20 healthy and 34 sarcoid-affected donkeys were subject to polymerase chain reaction (PCR) using papillomaviral specific primers. Analysis of blood derived DNA samples failed to demonstrate the presence of papillomaviral DNA in any animal. Screening of 37 matched sarcoid derived DNA samples confirmed the presence of spy in 34 diseased donkeys. This study supports the hypothesis of spy as an aetiological agent in the equine sarcoid and suggests that latent virus in circulating peripheral blood cells does not play a role in the pathogenesis and epidemiology of the equine sarcoid.