Re-infection of the prion from the scrapie-infected cell line SMB-S15 in three strains of mice, CD1, C57BL/6 and Balb/c

Abstract

It is well known that the SMB-S15 cell line was originally established by cultures from the brains of mice affected by the Chandler scrapie strain, and this cell line may express PrPSc permanently. However, the infectivity of the S15-derived prions on experimental animals has not yet been well documented. In the present study, the cell lysates of SMB-S15 were intracerebrally inoculated into three different strains of mice, namely C57BL/6, Balb/c and CD1. Prion protein (PRNP) gene sequencing revealed the same encoded PrP proteins in the sequences of amino acids in the three strains of mice, in addition to a synonymous single nucleotide polymorphism (SNP) in CD1 mice. All infected mice developed typical experimental transmissible spongiform encephalopathies (TSEs) approximately six months post-infection. The clinical features of three infected mice were comparable. The pathogenic characteristics, such as the electrophoretic and glycosylation profiles and proteinase K (PK) resistance of PrPSc molecules, as well as the neuropathological characteristics, such as spongiform vacuolation, PrPSc deposits in cortex regions, astrogliosis and activated microglia, were also similar in all three strains of infected mice. However, PrPSc deposits in the cerebellums of CD1 mice were significantly fewer, which was linked with the observation that lower numbers of CD1 mice presented cerebellum-associated symptoms. Successive inoculation of the individual strains of mice with brain homogenates from the infected mice also induced typical experimental scrapie. The data in the present study thus confirm that the prion agent in SMB-S15 cells causes stable infectivity in different types of mice with distinct phenotypes after long-term propagation in vitro. The present study also provides further scrapie rodent models, which may be used in further studies.

MiRNA expression profiles in the brains of mice infected with scrapie agents 139A, ME7 and S15

“…Four C57BL mice infected with scrapie strains 139A or ME7, as well as four secondary passage mice that were infected with the lysates of SMB-S15 cells (S15) 12 were used in this study. The procedure for the intracerebral inoculation of the scrapie agents into mice was described previously.…”

“…The procedure for the intracerebral inoculation of the scrapie agents into mice was described previously. 12, 13 Briefly, under halothane anaesthesia, 28-day-old C57BL mice received an intracerebral inoculation with 1 μL of 10% brain homogenates from mice infected with the individual scrapie agents. The animals were monitored twice a week before clinical signs of infection were observed by experienced staff and then once per day after the appearance of the clinical symptoms until the animals died.…”

“…The incubation times of the mice infected with agents 139A, ME7 and S15 were 183.9±23.1, 184.2±11.8 and 153.0±2.2 days, respectively. 12 The presence of proteinase K (PK)-resistant PrP Sc in the brains of the infected mice was evaluated by PrP-specific Western blots; these results are shown in Supplementary Figure S1.…”

Decrease of RyR2 in the prion infected cell line and in the brains of the scrapie infected mice models and the patients of human prion diseases

“…SMB-PS and SMB-S15 cell lines were obtained from the Roslin Institute (UK) and cultured in Dulbecco's modified Eagle's medium (Gibco, USA) supplemented with 12% fetal bovine serum (FBS) (AusgeneX, Australia) according to the protocol described previously [17,18]. Cell line SMB-S15 was originally infected with scrapie strain Chandler and the PrP Sc replication was persistently observed during cell passages.…”

“…The incubation times of 139A and ME7 intracerebrally infected mice were 183.9 § 23 and 184.2 § 11.2 days, respectively [21]. S15 infected mice were intracerebrally injected with the lysates of SMB-S15 cells, with the incubation period of 172.8 § 1.8 days [17]. The clinical and neuropathological features of those three mice scrapie were thoroughly addressed elsewhere.…”