Alverson Janet, O'Rourke Katherine I, Baszler Timothy V
Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164, USA.
USDA, ARS, Animal Disease Research Unit, 3003 ADBF, Washington State University, Pullman, WA 99164, USA.
J Gen Virol. 2006 Apr;87(Pt 4):1035-1041. doi: 10.1099/vir.0.81418-0.
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.
当胎儿的基因型为易感基因型（VRQ/VRQ、ARQ/VRQ或ARQ/ARQ）时，来自感染羊瘙痒病母羊的胎盘已被证明会积累PrPSc。先前已证明，基因型为ARR/ARR、ARQ/ARR和ARQ/VRR的胎儿的子叶对PrPSc积累具有抗性。通过使用来自自然感染羊瘙痒病羊群的母羊，检查了不同基因型多胞胎胎儿的子叶。在基因型为ARQ/ARQ的胎儿子叶中检测到了PrPSc，但在其基因型为ARQ/ARR的异卵双胞胎的子叶中未检测到。这证实了早期关于这些基因型单胎胎儿的报道，但这是首次描述在每种基因型各一个的双胞胎胎儿中的这一发现。还证明，基因型为ARQ/VRQ和ARQ/ARQ的同胞胎儿的子叶，其PrPSc积累模式取决于母羊的基因型是ARQ/ARQ还是ARQ/VRQ。最后表明，当具有抗性基因型的胎儿与PrPSc检测呈阳性的易感基因型胎儿共用同一个妊娠子宫角时，其胎儿子叶对PrPSc呈弱阳性。此外，在与雄性胎儿共用一个子宫角的雌性胎儿的子叶中发现了雄性特异性的Sry基因的PCR产物。这表明，位于同一子宫角的胎盘小叶和胎儿之间会发生一些胎儿血液的共享，这可能导致具有抗性基因型的子叶中PrPSc积累。
