Monoclonal and polyclonal antibodies for ante- and post-mortem detection of PrPSc in sheep

Abstract

Scrapie is a disease that affects sheep and goats and is characterized by the accumulation of an abnormal isoform (PrPSc) of the cellular prion protein, PrPC, in the central nervous system (CNS) and in lymphoid tissues. Detection of PrPSc 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 efficacy of monoclonal antibodiesF89/160.1.5, F99/97.6.1, and P4 and polyclonal antibodies M52 and R486 in the detection of PrPSc 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 confirmed the granular deposition of PrPSc 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-specific staining. The testing of positive control tonsil samples with polyclonal and monoclonal antibodies identified positive control-specific 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, their use is not advisable because of possible false positive reactions. The polyclonal antibody M52 was able to identify PrPC in brain and spleen samples by WB but other lymphoid tissues were negative.