NR AWEZ
AU Foster,J.D.; Houston,F.; Hunter,N.
TI The effect of age at challenge on subsequent development of BSE in sheep
QU International Conference - Prion 2006: Strategies, advances and trends towards protection of society - 3.10.-6.10.2006, Torino, Italy, Lingotto Conference Centre - Poster sessions PA-16
PT Konferenz-Poster
AB Previous studies involving the oral dosing of sheep of susceptible PrP genotypes with BSE have shown wide variation of incubation period and less than 100% incidence of disease. Although these studies did not show any evidence of an age related effect on incubation, sheep were not challenged at less than six months of age. In very young lambs (one day) gut associated lymphoid tissue (GALT) is much more extensive than in animals of a few months or even weeks. The process of infection may depend on the extent of lymphoid tissue in the gut and so the greater the amount the better the chance of infection occurring. However, other factors may influence the ability of the young lamb to become infected following oral challenge. These include the reflex operation of the oesophageal groove which allows lambs to ingest milk directly into the abomasums thereby aiding the direct absorption of larger protein molecules and possibly BSE. At this time too the level of proteolytic activity in the digestive tract is low to facilitate the transfer of maternal immunoglobulins into the lamb's circulation. This also might aid the absorption of BSE across the lamb's gut. The purpose of this study is to establish whether age at challenge has an effect on the incubation and disease incidence by dosing day-old lambs, as well as some older age groups. These included day-old lambs, 2-3 weeks (lamb still suckling), 12 weeks (weaning), 26 weeks (young adult) and 52 weeks (adult). The dosing regime also needed to reflect the relative size of animal at the time of dosing and for this reason different doses were used at each stage. These comprised 1.0g, 0.5g and 0.05g per animal, as well as 0.5g of control material (uninfected brain) for each age group. All age groups have been dosed and each have produced clinical cases, apart from the controls. From the results it is clear that the 14-21 day old lamb is most at risk from BSE by the ingestion of disease. All three dosing regimes in this age group have induced a high incidence of disease. There is a considerable number of survivors from the other age groups, which continue to be monitored.
AD J. Foster, N. Hunter: Institute for Animal Health, Neuropathogenesis Unit, Kings Buildings, West Mains Road, Edinburgh EH9 3JF, UK; F. Houston: Institute for Animal Health, Compton, Newbury, RG20 7NN, UK. E-mail: Jim.foster@bbssrc.ac.uk
SP englisch
PO Italien