Tonsil biopsy tissue was examined by PrP immunohistochemistry using anti-PrP monoclonal antibody ICSM 35 and no abnormal staining of follicular centres or other areas was seen, in sharp contrast to vCJD tonsil (Wadsworth et al. 2001; figure 3b). This evidence concerns the gene PRNP and variant Creutzfeldt-Jakob disease.