A monoclonal antibody that enables specific immunohistological detection of prion protein in bovine spongiform encephalopathy cases

Species-specificity of a panel of prion protein antibodies for the immunohistochemical study of animal and human prion diseases

Monoclonal antibodies to the prion protein (PrP) have been of critical importance in the neuropathological characterization of PrP-related disease in men and animals. To determine the influence of species-specific amino-acid substitutions recognized by monoclonal antibodies, and to investigate the immunohistochemical reactivity of the latter, analyses were carried out on brain sections of cattle with bovine spongiform encephalopathy, sheep with scrapie, mice infected with scrapie, and human beings with Creutzfeldt-Jakob disease (CJD) or Gerstmann-Sträussler-Sheinker disease (GSS). Immunoreactivity varied between the antibodies, probably as the result of differences in the amino-acid sequence of the prion protein in the various species. Some monoclonal antibodies against mouse recombinant PrP gave strong signals with bovine, ovine and human PrP(Sc), in addition to murine PrP(Sc), even though the amino-acid sequences determined by the antibody epitope are not fully identical with the amino-acid sequences proper to the species. On the other hand, in certain regions of the PrP sequence, when the species-specificity of the antibodies is defined by one amino-acid substitution, the antibodies revealed no reactivity with other animal species. In the region corresponding to positions 134-159 of murine PrP, immunohistochemical reactivity or species-specificity recognized by the antibodies may be determined by one amino acid corresponding to position 144 of murine PrP. Not all epitopes recognized by a monoclonal antibody play an important role in antigen-antibody reactions in immunohistochemistry. The presence of the core epitope is therefore vital in understanding antibody binding ability.

Development of a monoclonal antibody-based immunohistochemistry method for BSE surveillance in China

Five hybridoma cell lines secreting anti-PrP antibodies were established from the fusion between mouse myeloma Sp2/0 and spleen cells from mice immunized with recombinant Chinese Luxi yellow cattle (Bos taurus, Luxi) PrP (24-234) or recombinant Chinese small-tailed Han sheep PrP (94-227). According to their Western blot reactivity, five monoclonal antibodies (mAbs) could be divided into two groups. Group A, mAbs 1H2, 4C6, and 4C11 recognized re-PrP, PrP(C), and PrP(Sc) from both bovine and sheep. Group B, mAbs 2H3 and 4H10 only recognized re-PrP and PrP(Sc) of sheep, and especially, these two mAbs could not recognize PrP(C) from both bovine and sheep. In immunohistochemistry (IHC) test, mAb 4C11 immunostained the PrP(Sc) accumulation in tissue sections from BSE cattle and Scrapie sheep, and compared with mAb 6H4, it had the same immunohistochemical pattern. An IHC method based on mAb 4C11 for the detection of BSE was established and had been applied for the long-term surveillance of BSE in China. From 2001 to 2004, 12,692 samples from the whole country had been tested and all had negative results.

Proteinase K enhanced immunoreactivity of the prion protein-specific monoclonal antibody 2A11

Here, we report the development and further characterisation of a novel PrP-specific monoclonal antibody: 2A11. By Western blot analysis, 2A11 reacts with PrPC from a variety of species including cow, sheep, pig, hamster, rabbit, cat, dog, deer and mouse but fails to react with human, chicken and turtle PrP. Reactivity to PrPC in Western blot was found to be dependent on the redox state of the protein since binding of mAb 2A11 to its epitope was more effective in reducing conditions. 2A11 binding site was mapped within a region comprised by residues 171-179 (six octarepeats bovine PrP notation; 163-171 for the ovine PrP notation). Interestingly, in immunohistochemistry (IHC) analysis, immunoreactivity was greatly enhanced after proteinase K (PK) sample treatment, while little or no reaction was observed in non-PK-treated BSE samples and samples from healthy animals. Quantitative differences in reactivity to BSE prions after PK treatment were also observed, to a lesser extent, by Western blot analysis. Since definitive diagnosis of prion diseases rely on IHC assays of proteinase K-treated samples, the use of mAb 2A11 might contribute to reduce the occurrence of false positive detection due to incomplete proteinase K digestion.