Monoclonal and polyclonal antibodies for ante - and post-mortem detection of PrP Sc in sheep Utilização de anticorpos monoclonais e policlonais para diagnóstico ante- e post-mortem do scrapie

Scrapie is a disease that affects sheep and goats and is characterized by the accumulation of an abnormal isoform (PrP Sc ) of the cellular prion protein, PrP C , in the central nervous system (CNS) and in lymphoid tissues. Detection of PrP Sc in these tissues can be attempted by a variety of techniques, including immunohistochemistry (IHC) and western blotting (WB), for which a wide range of monoclonal and polyclonal antibodies are commercially available. The objective of this study was to test and compare the ef?cacy of monoclonal antibodiesF89/160.1.5, F99/97.6.1, and P4 and polyclonal antibodies M52 and R486 in the detection of PrP Sc in lymphoid and CNS tissue samples by using IHC. Positive and negative control samples of sheep brain and tonsils were provided by the Animal Health and Veterinary Laboratories Agency (AHVLA, UK). The IHC examination of CNS samples with both monoclonal and polyclonal antibodies con?rmed the granular deposition of PrP Sc in the neurons of the positive control tissues. However, while the monoclonal antibodies did not produce positive reactions in the negative controls, the polyclonal antibodies showed some non-speci?c staining. The testing of positive control tonsil samples with polyclonal and monoclonal antibodies identi?ed positive control-speci?c reactions, whereas the negative control tissues were IHC-negative with all antibodies, although P4 and the polyclonal antibodies produced some background staining. In summary, although the polyclonal antibodies may be more accessible, in this study their use is not advisable because of possible false positive reactions. The polyclonal antibody M52 was able to identify PrP C in brain and spleen samples