Edited by Paul FraserThe precise mechanism underlying the conversion of normal prion protein ( Sc by using a modified PMCA performed with baculovirusderived recombinant PrP (Bac-PrP) as a substrate. The addition of heparan sulfate (HS) or its analog heparin (HP) restored the conversion efficiency in PMCA that was inhibited through nucleic acid depletion. Moreover, the PMCA products obtained under these conditions were infectious and preserved the properties of the input PrP Sc . These data suggest that HS and HP play the same role as nucleic acids in facilitating faithful replication of prions in PMCA. Furthermore, we showed that HP binds to both Bac-PrP and Bac-PrP Sc through the sulfated groups present on HP and that the N-terminal domain of Bac-PrP Sc might potentially not be involved in the binding to HP. These results suggest that the interaction of GAGs such as HS and HP with PrP C and/or PrP Sc through their sulfate groups is critical for the faithful replication of prions.

ABSTRACT. A classical type of bovine spongiform encephalopathy (C-BSE), recognized in 1987, had a large impact on public health due to its zoonotic link to variant Creutzfeldt-Jakob disease by the human consumption of dietary products contaminated with the C-BSE prion. Thus, a number of countries implemented BSE surveillance using rapid post-mortem test kits that were approved for detection of the C-BSE prion in the cattle brain. However, as atypical BSE (L-and H-BSE) cases emerged in subsequent years, the efficacy of the kits for the detection of atypical BSE prions became a matter of concern. In response to this, laboratories in the European Union and Canada evaluated the kits used in their countries. Here, we carried out an evaluation study of NippiBL Ò , a kit currently used for BSE screening in Japan. By applying the kit to cattle brains of field cases of C-BSE and L-BSE, and an experimental case of H-BSE, we showed its comparable sensitivities to C, L-, and H-BSE prions, and satisfactory performance required by the European Food Safety Authority. In addition to NippiBL Ò , two kits (TeSeE Ò and FRELISA Ò ) formerly used in Japan were effective for detection of the L-BSE prion, although the two kits were unable to be tested for the H-BSE prion due to the discontinuation of domestic sales during this study. These results indicate that BSE screening Correspondence to: Ken'ichi Hagiwara;

In prion diseases, abnormal prion protein (PrPSc) is considered as the main component of the infectious agent. Delineation of PrPSc conformation is expected to be a critical factor in understanding properties of prions. However, practical methods to differentiate between conformers of PrPSc are inadequate. Here, we used two PrPSc-specific monoclonal antibodies (mAbs), 3B7 and 3H6, and found that mAb 3H6 detected a limited portion of PrPSc in five mice-adapted prion strains. The quantity of mAb 3H6-precipitated PrPSc was significantly lesser in 22L compared to other strains. This result provides a direct evidence of the conformational heterogeneity of PrPSc within the prion strains. Conformation-specific probes, like these mAbs, have the potential to be powerful tools for investigating conformational variations in PrPSc.

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