Question
To what extent (a) antibody and (b) other research carried out at the Central Veterinary Laboratory into the infectivity of BSE in the ileum indicates infectivity of BSE eight months prior to an animal displaying clinical signs of BSE. - (Holding answer 17 June 1996).
Answer
Mr. Campbell-Savours: to ask the Minister of Agriculture, Fisheries and Food to what extent (a) antibody and (b) other research carried out at the central veterinary laboratory into the infectivity of BSE in the ileum indicates infectivity of BSE eight months prior to an animal displaying clinical signs of BSE.[32324] Mrs. Browning: [holding answer 17 June 1996]: No PrP antibody test has been established that in BSE can specifically detect the altered protein in the ileum-- assuming the protein to be a proxy for infectivity. Further work is planned in this area. Research at CVL into infectivity of BSE in the ileum has been confined to mouse bioassay of this tissue from cattle experimentally infected by oral dosing using a large dose of affected cow brains. Groups of infected cattle were then killed at sequential four month intervals and their tissues were sampled for bioassay of infectivity. Results of the study are incomplete, but so far infectivity has been detected in ileum of cattle from six months to 18 months after dosing. Those cattle which remained in the study developed clinical signs of BSE at 35 to 37 months after dosing. The results of assays started after 18 months post challenge are not yet available. Thus the studies indicate that, under these specified experimental conditions, infectivity is detectable by bioassay in mice from six months to at least 18 months after dosing. There is no evidence from the research or otherwise at present that infectivity and/or the altered PrP protein in BSE can be detected eight months prior to the onset of clinical disease.