RESUMEN
AIM: CH1641 was discovered in 1970 as a scrapie isolate that was unlike all other classical strains of scrapie isolated so far. We performed bio-assays of CH1641 in mice in order to further characterise this specific isolate. METHODS: We inoculated the original CH1641 isolate into ovine and bovine prion protein (PrP) transgenic mice as well as wild-type mice. In addition, we performed cross- and back passages between the various mouse lines to examine if one identical prion strain was isolated in all mouse lines or whether multiple prion strains exist in CH1641. RESULTS: We report the first successful transmission of CH1641 to wild-type RIII mice and via RIII mice to wild-type VM mice. Unexpectedly, analysis of the protease-resistant prion protein (PrPres ) in wild-type mice showed a classical scrapie banding pattern differing from the banding pattern of the original CH1641 isolate. Cross- and back passages of CH1641 between the various mouse lines confirmed that the same prion strain had been isolated in all mouse lines. CONCLUSIONS: The CH1641 isolate consists of a single prion strain but its molecular banding pattern of PrPres differs between wild-type mice and PrP transgenic mice. Consequently, molecular banding patterns of PrPres should be used with caution in strain typing since they do not solely depend on the properties of the prion strain but also on the host prion protein.
Asunto(s)
Priones , Scrapie , Ratones , Animales , Bovinos , Ovinos , Priones/metabolismo , Scrapie/metabolismo , Proteínas Priónicas/genética , Proteínas PrPSc/metabolismo , Ratones TransgénicosRESUMEN
Genetic susceptibility to scrapie, a fatal disease of sheep and goats, is modulated by polymorphisms in the prion protein (PrP). Neither the frequency of the PrP genotypes nor their association with animal performance has been investigated in a large multibreed Irish sheep population. Scrapie genotypes were available on 16 416 animals; the breeds represented included purebred Belclare (733), Charollais (333), Suffolk (739), Texel (1 857), Vendeen (191), and crossbreds (12 563). Performance data on lambing, lamb and ewe performance as well as health traits were available. The association between alternative approaches of describing the PrP genotype (i.e. 15 individually called PrP genotypes, five genotype classes representing susceptibility to scrapie, or number of ARR haplotypes) and animal performance were quantified using animal linear mixed models. All 15 of the possible scrapie genotypes were detected, although the frequency differed by breed. The frequency of the five PrP haplotypes in the entire population were 0.70 (ARR), 0.15 (ARQ), 0.11 (ARH), 0.02 (AHQ) and 0.01 (VRQ); the most susceptible haplotype (VRQ) was only detected in purebred Texels and crossbreds. No association was detected between the PrP genotype of either the animal or dam and any of the lambing traits (i.e. lambing difficulty score, perinatal mortality and birth weight). With the exception of ultrasound muscle depth, no association between the PrP genotype and any of the lamb performance traits (i.e. lamb BW and carcass) was observed. Lambs carrying the category four PrP genotype (i.e. ARR/VRQ) had 1.20 (SE = 0.45) mm, 1.38 (SE = 0.12) mm, 1.47 (S = 0.25) mm shallower ultrasound muscle depth relative to lambs of the less susceptible scrapie categories of 1, 2, 3, respectively (P < 0.05). Nonetheless, no association between PrP genotype and lamb carcass conformation, the ultimate end goal of producers, was detected. Ewe litter size, body condition score or lameness did not differ by PrP genotype of the ewe (P > 0.05). For ewe mature BW, ARH/VRQ ewes differed from most other ewe PrP genotypes and were, on average, 3.79 (SE = 1.66) kg heavier than ARR/ARR genotype ewes. Lamb dag score differed by dam PrP genotype (P < 0.05), although the differences were small. Results from this study show that scrapie is segregating within the Irish sheep population, but the PrP genotype was not associated with most traits investigated and, where associations were detected, the biological significance was minimal. This suggests minimal impact of selection on PrP genotype on performance, at least for the traits investigated in the present study.
Asunto(s)
Priones , Scrapie , Enfermedades de las Ovejas , Animales , Femenino , Predisposición Genética a la Enfermedad , Genotipo , Proteínas Priónicas/genética , Priones/genética , Scrapie/genética , Ovinos/genéticaRESUMEN
Cultured cells are valuable models to study prion infections at the cellular level. Unfortunately, the vast majority of cell lines are resistant to the propagation of prion agents. The rabbit epithelial RK13 cell line is among the few cell lines permissive to prion infection. When genetically engineered to express heterologous PrP proteins, RK13 cells become permissive to several strains of prions from various animal species. Here, we describe the generation of stable RK13 cell clones expressing a heterologous PrP protein in an inducible manner, the establishment and maintenance of chronically infected cultures, and the selection of cell clones suitable for cell-based titration of prions.
Asunto(s)
Células Epiteliales/metabolismo , Efecto Fundador , Immunoblotting/métodos , Proteínas PrPSc/genética , Animales , Encéfalo/metabolismo , Encéfalo/patología , Técnicas de Cultivo de Célula , Línea Celular , Células Clonales , Clonación Molecular , Endopeptidasa K/química , Células Epiteliales/patología , Expresión Génica , Humanos , Ratones , Plásmidos/química , Plásmidos/metabolismo , Proteínas PrPSc/química , Proteínas PrPSc/metabolismo , Pliegue de Proteína , Conejos , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMEN
Prion diseases (PDs) are fatal neurological disorders that are thought to be caused by the accumulation of an altered variant of a benign, widely expressed protein (PrPC) into a distinct pathological conformation(s) (PrPSc). The PDs are so rare but lethal pathologies that need an early diagnosis to adequately support the infected patient. A maternal-fetal transmission during pregnancy has been supposed to be on the basis of animal studies, but till now the effective vertical transmission in humans has not been proved. We present a case of infected pregnant woman with a peculiar pregnancy course and outcome. We also provided a systematic literature review to find the best obstetrical management of women affected by prionic disease during pregnancy. The available data underline the potential risk of prenatal and postnatal transmission of the disease but do not permit to define the exact molecular mechanism of transmission, the best follow-up and recommendations that are useful in both obstetrical and neonatal practice. At present awaiting for further clarifications about this topic, it is mandatory to personalize the management of this rare pregnancy complication according to the maternal-fetal well-being status.
Asunto(s)
Síndrome de Creutzfeldt-Jakob/terapia , Síndrome de Creutzfeldt-Jakob/transmisión , Transmisión Vertical de Enfermedad Infecciosa , Complicaciones Infecciosas del Embarazo , Adolescente , Adulto , Femenino , Humanos , Embarazo , Adulto JovenRESUMEN
Upon prion infection, abnormal prion protein (PrP (Sc) ) self-perpetuate by conformational conversion of α-helix-rich PrP (C) into ß sheet enriched form, leading to formation and deposition of PrP (Sc) aggregates in affected brains. However the process remains poorly understood at the molecular level and the regions of PrP critical for conversion are still debated. Minimal amino acid substitutions can impair prion replication at many places in PrP. Conversely, we recently showed that bona fide prions could be generated after introduction of eight and up to 16 additional amino acids in the H2-H3 inter-helix loop of PrP. Prion replication also accommodated the insertions of an octapeptide at different places in the last turns of H2. This reverse genetic approach reveals an unexpected tolerance of prions to substantial sequence changes in the protease-resistant part which is associated with infectivity. It also demonstrates that conversion does not require the presence of a specific sequence in the middle of the H2-H3 area. We discuss the implications of our findings according to different structural models proposed for PrP (Sc) and questioned the postulated existence of an N- or C-terminal prion domain in the protease-resistant region.