[1] Univ Reading, Sch Anim & Microbial Sci, Div Cell & Mol Biol, Reading RG6 6AJ, Berks, England
[2] Western Gen Hosp, Edinburgh Breast Unit Res Grp, Edinburgh EH4 2XU, Midlothian, Scotland
[3] Vet Labs Agcy, Dept Bacterial Dis, Surrey KT15 3NB, England
[4] Vet Labs Agcy, Dept TSE Mol Biol, Surrey KT15 3NB, England