Abstract: The invention relates to a new aviadenovirus which was isolated from a pigeon. The aviadenovirus according to the present invention comprises group-I specific antigen and cannot be neutralized by antiserum against any of the FAV serotypes 1-12. The present invention also relates to an antibody or antiserum immunoreactive with a fibre of the new aviadenovirus, a fibre thereof as well as a vaccin against PiAV related diseases comprising a chemically or physically inactivated virus an attenuated virus, a fibre or fragment thereof, a host cell transformed with a nucleic acid sequence encoding an amino acid sequence comprising an immunogenic determent or a functional variant thereof of a fibre of the aviadenovirus according to the present invention, together with a pharmaceutical carrier.