Second passage experiments of chronic wasting disease in transgenic mice overexpressing human prion protein

Abstract

Chronic wasting disease (CWD) is a prion disease of cervids including deer, elk, reindeer, and moose. Human consumption of cervids is common, therefore assessing the risk potential of CWD transmission to humans is critical. In a previous study, we tested CWD transmission via intracerebral inoculation into transgenic mice (tg66 and tgRM) that over-expressed human prion protein. Mice screened by traditional prion detection assays were negative. However, in a group of 88 mice screened by the ultrasensitive RT-QuIC assay, we identified 4 tg66 mice that produced inconsistent positive RT-QuIC reactions. These data could be false positive reactions, residual input inoculum or indicative of subclinical infections suggestive of cross species transmission of CWD to humans. Additional experiments were required to understand the nature of the prion seeding activity in this model. In this manuscript, second passage experiments using brains from mice with weak prion seeding activity showed they were not infectious to additional recipient tg66 mice. Clearance experiments showed that input CWD prion seeding activity was eliminated by 180 days in tg66 mice and PrPKO mice, which are unable to replicate prion protein, indicating that the weak positive levels of seeding activity detected at later time points was not likely residual inoculum. The failure of CWD prions to cause disease in tg66 after two sequential passages suggested that a strong species barrier prevented CWD infection of mice expressing human prion protein.

Scrapie versus Chronic Wasting Disease in White-Tailed Deer

“…Because of the National Scrapie Eradication Program in 2001, cases of classical scrapie in farmed sheep have dramatically dropped and no case of classical scrapie has detected in the United States since January 2021 ( https://www.aphis.usda.gov/sites/default/files/scrapie-quarterly-report-june-2024.pdf ). The potential for zoonoses of cervid-derived PrP Sc is still not well understood ( 6 , 18 , 45 – 47 ); however, interspecies transmission can increase host range and zoonotic potential ( 48 – 50 ). Therefore, to protect herds and the food supply, suspected cases of WTD scrapie should be handled the same as cases of CWD.…”

Sporadic Creutzfeldt–Jakob disease infected human cerebral organoids retain the original human brain subtype features following transmission to humanized transgenic mice

“…In our initial study ([ 10 ] and Additional File 1 : Figure S1), we followed the residual inoculum, as detected by RT-QuIC, and observed the complete disappearance around 25–30 dpi followed by the re-emergence at later time points of RT-QuIC positivity to levels greater than those immediately following inoculation. Since the RT-QuIC assay has been demonstrated to be more sensitive than animal bioassay and able to detect sub-infectious levels of PrP D [ 28 , 38 – 40 ], the complete loss of RT-QuIC detection of the inocula suggests that, if present, the residual inocula in the organoids would not be sufficient to cause disease in animals, even following subpassage [ 41 ]. Instead, this suggests that organoid derived PrP D is responsible for both MV1 and MV2 infections despite the long incubation period and low detection in the first passage MV1-OH inoculated mice.…”

A PrP EGFR signaling axis controls neural stem cell senescence through modulating cellular energy pathways

“…The establishment of the NSC cultures has been described previously ( 56 , 57 ). Briefly, the subventricular zone was removed from three C57BL/10SnJ WT, PrP-KO, and Tg44 GPI anchorless mice ( 58 ) and separated into a cell suspension using the Stem Cell Technologies NeuroCult Enzymatic Dissociation Kit for Adult CNS Tissue (Mouse and Rat) as per the manufacturer’s instructions. NSC suspensions were cultured in low adhesion plasticware in complete proliferation media (NeuroCult Proliferation Kit [Stem Cell Technologies] supplemented with 20 ng/ml EGF, 10 ng/ml FGF, and 2 μg/ml heparin).…”