Prion Infection of Muscle Cells In Vitro

Abstract

The prion agent has been detected in skeletal muscle of humans and animals with prion diseases. Here we report scrapie infection of murine C2C12 myoblasts and myotubes in vitro following coculture with a scrapieinfected murine neuroblastoma (N2A) cell line but not following incubation with a scrapie-infected nonneuronal cell line or a scrapie brain homogenate. Terminal differentiation of scrapie-infected C2C12 myoblasts into myotubes resulted in an increase in the expression of the disease-specific prion protein, PrP Sc . The amount of scrapie infectivity or PrP Sc in C2C12 myotubes was comparable to the levels found in scrapie-infected N2A cells, indicating that a high level of infection was established in muscle cells. Subclones of scrapie-infected C2C12 cells produced high levels of PrP Sc in myotubes, and the C-terminal C2 polypeptide fragment of PrP Sc was found based on deglycosylation and PrP Sc -specific immunoprecipitation of cell lysates. This is the first report of a stable prion infection in muscle cells in vitro and of a long-term prion infection in a nondividing, differentiated peripheral cell type in culture. These in vitro studies also suggest that in vivo prion infection of skeletal muscle requires contact with prion-infected neurons or, possibly, nerve terminals.

Canine MDCK cell lines are refractory to infection with human and mouse prions

“…Moreover, the common laboratory fibroblast cell lines 3T3-NIH and L929 were found to be susceptible to infection with mouse-adapted scrapie [12]. Most recently, scrapie infection of murine C2C12 myoblasts and myotubes in vitro following co-culture with scrapie-infected N2a cells was demonstrated, albeit infection did not occur after incubation with a scrapie-infected non-neuronal cell line or a scrapie brain homogenate [41]. The above findings indicate that any cell type that expresses the cellular prion protein (PrP C ) may be capable of supporting prion-replication.…”

Cell models of prion infection

“…Notably, the mouseadapted bovine spongiform encephalopathy (BSE) agent was successfully propagated in MG20 cells. Infection of a skeletal myoblast cell line (C2C12) has been described recently [39], and could be used to investigate prion infection of muscles observed in sheep and cervids. While all the aforementioned cell models are permissive to mouse-adapted prion strains, a cell line (HaB) stably infected with hamster prions has been described in the past [136].…”

“…infectious brain homogenate) with cultured target cells. However, several independent studies have recently shown that prion transmission is much more efficient when live infected biological material is used as the source of infectivity [39,65,99]. Further investigation into the underlying active biological processes will be necessary to optimise prion transmission to cultured cells.…”

“…While the underlying mechanisms remain to be characterised, it seems that prion spreading among cultured cells can occur through different modes. Further studies will be necessary to test the interesting possibility that mechanisms of cell-to-cell prion spreading may vary depending on the cell type [39,99] and/or the prion strain.…”

“…not previously adapted to rodents) to cultured cells, and this also provided evidence that PrP res can be readily detected in infected cells from the non-neuronal lineage. Since then, prion multiplication was demonstrated in several other non-neuronal cell systems, including fibroblasts [116,147], muscle cells [39], microglial cells [61], and another natural isolate (from chronic wasting disease) was successfully transmitted to a mule deer cell line [116].…”