IMMUNOBIOLOGY OF SCRAPIE VIRUS INFECTION

点击翻译按钮获取中文摘要

Scrapie is a naturally occurring spongiform encephalopathy of sheep and goats which causes clinical and pathological changes similar to those of Creutzfeldt-Jakob and Kuru diseases of man. The infectious agent is markedly resistant to agents that inactivate most viruses and disease results in no detectable host immune response. The intimate association of scrapie with host protein may account for many of its unusual features. In order to obtain agent free of tissue contaminants, we have sought to establish high titered scrapie infected tissue culture cell lines. Neuroblastoma cell lines were successfully infected with scrapie agent and analyzed by two-dimensional gel electrophoresis for scrapie-specific proteins and for the presence of the "prion" protein. No protein unique to either the uninfected or infected culture was identified. Attempts to metabolically label scrapie associated nucleic acids were also unsuccessful. Although the cell line maintains significant infectivity, it may be too little to allow detection of certain Sc related functions. Therefore, an attempt will be made to clone infected cells from the cultures thus enriching for Sc related functions. In order to study the relation of the prion protein to scrapie disease a cDNA clone of the scrapie prion protein (PrP27-30) was isolated using an oligonucleotide probe based on the predicted mRNA sequence of a portion of this protein. The partial DNA sequence of this clone indicated that it was identical to the predicted PrP27-30 mRNA. Hybridization of this clone detected a 2.4-2.5 kb mRNA band in both scrapie-infected and uninfected mouse and hamster brain, but not in spleen or liver. Thus, PrP27-30 mRNA was not scrapie-specific, but instead appeared to encode a normal brain protein. Similar approaches will be used to search for scrapie specific markers.