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From: TSS ()
In Reply to: BSE agent in spleen from an ARR/ARR orally exposed sheep posted by TSS on March 12, 2006 at 6:30 am:
PrPSc accumulation in fetal cotyledons of scrapie-resistant lambs is influenced by fetus location in the uterus 1 USDA, ARS, Animal Disease Research Unit, 3003 ADBF, Washington State University, Pullman, WA 99164, USA Placentae from scrapie-infected ewes have been shown to accumulate PrPSc when the genotype of the fetus is of a susceptible genotype (VRQ/VRQ, ARQ/VRQ or ARQ/ARQ). Cotyledons from fetuses of genotypes ARR/ARR, ARQ/ARR and ARQ/VRR have previously been shown to be resistant to PrPSc accumulation. By using ewes from a naturally infected scrapie flock, cotyledons from fetuses of multiple births of different genotypes were examined. PrPSc was detected in fetal cotyledons of genotype ARQ/ARQ, but not in cotyledons from their dizygotic twin of genotype ARQ/ARR. This confirms earlier reports of single fetuses of these genotypes, but is the first description of such a finding in twin fetuses, one of each genotype. It is also demonstrated that cotyledons from sibling fetuses of genotypes ARQ/VRQ and ARQ/ARQ have different patterns of PrPSc accumulation depending on whether the dam is of genotype ARQ/ARQ or ARQ/VRQ. Lastly, it is shown that cotyledons from fetuses with resistant genotypes are weakly positive for PrPSc when they have shared the same pregnant uterine horn with a fetus of a susceptible genotype with cotyledons positive for the detection of PrPSc. Additionally, a PCR product for the Sry gene, a product specific to males, was found in cotyledons from female fetuses that had shared a uterine horn with a male fetus. This indicates that some sharing of fetal blood occurs between placentomes and fetuses residing in the same uterine horn, which can result in PrPSc accumulation in cotyledons with resistant genotypes. http://vir.sgmjournals.org/cgi/content/abstract/87/4/1035?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=prion&searchid=1142175475264_479&FIRSTINDEX=0&volume=87&issue=4&search_url=http%3A%2F%2Fvir.sgmjournals.org%2Fcgi%2Fsearch Guohua Yu, Jianquan Chen, Huiqing Yu, Siguo Liu, Juan Chen, Xujun Xu, Hongying Sha, Xufeng Zhang, Guoxiang Wu, Shaofu Xu, and Guoxiang Cheng P. L. Acutis, A. Bossers, J. Priem, M. V. Riina, S. Peletto, M. Mazza, C. Casalone, G. Forloni, G. Ru, and M. Caramelli TSS
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