Alteration of the biological and biochemical characteristics of bovine spongiform encephalopathy prions during interspecies transmission in transgenic mice models

Abstract

In the interspecies transmission of prions, the species barrier influences the susceptibility of the host. Bovine spongiform encephalopathy (BSE) prions affect a wide range of host species but do not affect hamsters. In order to study this species barrier, this study analysed the transmissibility of BSE prions to several lines of transgenic (Tg) mice, including those expressing mouse and hamster chimeric prion proteins (MH2M and MHM2 mice). BSE prions were transmitted to tga20, MHM2 and ICR mice, and the incubation period was approximately 400 days. Thus, these mice were classified as 'susceptible mice'. However, BSE prions were not transmitted to MH2M and TgHaNSE mice, and these mice were classified as 'resistant mice'. After the BSE prions were passaged once in wild-type mice, they could be transmitted to resistant mice. The characteristics of the accumulated abnormal isoform of PrP (PrP(Sc)) in susceptible and resistant mice were determined using Western blotting. A BSE-like glycoform pattern of PrP(Sc) was detected in all of the susceptible mice using two different antibodies that recognized either the N- or the C-terminal end of the 27-30 kDa protease-resistant fragment of PrP (PrP(27-30)) as the epitope. In contrast, proteinase digestion followed by deglycosylation analysis showed that, in addition to PrP(27-30), truncated PrP(Sc) fragments existed in resistant mice. These mixed PrP(Sc) fragments may have resulted from the adaptation of resistant mice to BSE prions.