A genome of an ovine adenovirus designated OAV287 is isolated from sheep and sequenced. Portions of the genome not essential for maintenance or viability of the virus can be deleted or altered. A nucleotide sequence encoding a non-adenoviral polypeptide can be incorporated into the genome. The a full-length clone of the genome can be provided as part of a plasmid or viral vector. Cells can be transformed with a vector of the invention such that they express an exogenous protein.