[1] Univ Edinburgh, Dept Biomed Sci, Edinburgh EH8 9XD, Midlothian, Scotland
[2] Inst Anim Hlth, Neuropathogenesis Unit, Edinburgh EH9 3JF, Midlothian, Scotland
[3] Univ Gottingen, Dept Neurol, D-37075 Gottingen, Germany
[4] Univ Gottingen, Dept Neuropathol, D-37075 Gottingen, Germany
[5] Univ Gottingen, Dept Psychiat, D-37075 Gottingen, Germany