Abstract
BackgroundTransmissible spongiform encephalopathy (TSE) diseases are known to be zoonotic diseases that can infect different kinds of animals. The transmissibility of TSE, like that of other infectious diseases, shows marked species barrier, either being unable to infect heterologous species or difficult to form transmission experimentally. The similarity of the amino acid sequences of PrP among species is believed to be one of the elements in controlling the transmission TSE interspecies. Other factors, such as prion strains and host's microenvironment, may also participate in the process.MethodsTwo mouse-adapted strains 139A and ME7 were cerebrally inoculated to Golden hamsters. Presences of scrapie associate fibril (SAF) and PrPSc in brains of the infected animals were tested by TEM assays and Western blots dynamically during the incubation periods. The pathogenic features of the novel prions in hamsters, including electrophoretic patterns, glycosylating profiles, immunoreactivities, proteinase K-resistances and conformational stabilities were comparatively evaluated. TSE-related neuropathological changes were assayed by histological examinations.ResultsAfter long incubation times, mouse-adapted agents 139A and ME7 induced experimental scrapie in hamsters, respectively, showing obvious spongiform degeneration and PrPSc deposits in brains, especially in cortex regions. SAF and PrPSc in brains were observed much earlier than the onset of clinical symptoms. The molecular characteristics of the newly-formed PrPSc in hamsters, 139A-ha and ME7-ha, were obviously distinct from the original mouse agents, however, greatly similar as that of a hamster-adapted scrapie strain 263 K. Although the incubation times and main disease signs of the hamsters of 139A-ha and ME7-ha were different, the pathogenic characteristics and neuropathological changes were highly similar.ConclusionsThis finding concludes that mouse-adapted agents 139A and ME7 change their pathogenic characteristics during the transmission to hamsters. The novel prions in hamsters' brains obtain new molecular properties with hamster-specificity.
Highlights
Transmissible spongiform encephalopathy (TSE) diseases are known to be zoonotic diseases that can infect different kinds of animals
The infectivity and transmissibility of scrapie, Creutzfeldt-Jakob disease (CJD) and bovine spongiform encephalopathy (BSE) lead those disorders to being nominated as transmissible spongiform encephalopathies (TSE)
Inoculations of mouse-adapted scrapie strains 139A and ME7 into hamsters induced experimental TSE after long incubation Brain homogenates of C57 mice infected with mouseadapted scrapie strains 139A and ME7 were intracerebrally inoculated into hamsters
Summary
Transmissible spongiform encephalopathy (TSE) diseases are known to be zoonotic diseases that can infect different kinds of animals. The similarity of the amino acid sequences of PrP among species is believed to be one of the elements in controlling the transmission TSE interspecies. Other factors, such as prion strains and host’s microenvironment, may participate in the process. A kind of transmissible neurodegenerative disease in sheep and goats described hundreds years ago, possesses similar neuropathological features and molecular properties as Creutzfeldt-Jakob disease (CJD) and Kuru in human and bovine spongiform encephalopathy (BSE) in cattle. The infectious protein, PrPSc, shares the same amino acid sequence as its normal isoform that distributes on the cellular membrane in several kinds cells with GPI-anchor [3]. Due to the conformational changes, PrPSc acquires several particular features once it forms, i.e. insoluble in ordinary degenerates, partially resistant to digestion of protease, resistant to inactivity of UV, radial and commonly used sterilization [4]
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