Frequent detection of Squirrel adenovirus 1 in red and grey squirrels in Scotland using a novel real-time PCR assay. Frequent detection of Squirrel adenovirus 1 in red and grey squirrels in Scotland using a novel real-time PCR assay

The Eurasian Red Squirrel (Sciurus vulgaris) is distributed throughout large parts of Europe and Asia. However, its distribution in certain regions of Europe is endangered by the invasive, non-native Grey Squirrel (Sciurus carolinensis). In 2013, a squirrel-associated adenovirus (SqAdV-1) was found in a red squirrel from Germany, which suffered from acute diffuse catarrhal enteritis, and the complete genome sequence was determined. Here, samples from red (n=25) and grey (n=12) squirrels collected in Scotland, UK, were analysed for the presence of this squirrel-associated virus. By using a newly developed real-time PCR targeting the adenoviral polymerase gene, viral DNA was detected in at least one of four tissue samples per specimen in 60.0% of the red squirrels and 41.7% of the grey squirrels. Exceptionally high viral genome load could bewere detected in the intestine and liver, but SqAdV-1 was also present in lung and kidney samples of affected animals. Complete genome sequence determination of a red squirrel-derived SqAdV-1 strain from Scotland indicated a very high similarity to the German strain described before. In conclusion, SqAdV-1 appears to beis widespread in the Scottish red and grey squirrel population, which highlights the necessity offor continuous wildlife surveillance. The novel real-time PCR assay offers a highly sensitive and robust method for this type of surveillance.