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''Transmissible Gastroenteritis Coronavirus (TGEV)'' is a virus belonging to the family ''Coronaviridae'', genus ''Alphacoronavirus'', species ''Alphacoronavirus 1''.〔(【引用サイトリンク】title=ICTV Taxonomy History for Alphacoronavirus 1 )〕 TGEV are enveloped viruses with a positive-sense single-stranded RNA genome and a helical symmetry. The genomic size of coronaviruses ranges from approximately 28.6 kilobases. Proteins that contribute to the overall structure of TGEV includes the spike (S), envelope (E), membrane (M) and nucleocapsid (N). Other coronaviruses belonging to ''Alphacoronavirus 1'' species include ''Feline coronavirus'', ''Canine coronavirus'' and ''Feline infectious peritonitis virus''. ==TGEV Biology== TGEV belongs to the coronaviridae family, genus ''Alphacoronavirus'', species ''Alphacoronavirus 1''. It is an enveloped virus with a positive single stranded RNA genome. TGEV has three major structural proteins, which are phosphoprotein (N), integral membrane protein (E1), and large glycoprotein (E2). The N protein encapsulates the genomic RNA, and the S protein forms viral projections. The 3' segment of about 8000 nucleotides encodes subgenomic RNAs. The remaining part of the genome encodes viral replicase. The three largest gene sequence from 5' to 3' is in the order of E2 to E1 to N. There are about seven other open reading frames that are not structurally related. There are very little overlaps among the genes, and is densely packed. A negative strand is synthesized to serve as a template for transcribing RNAs of one genome size and several subgenome sized RNAs. The E2 protein forms a petal-shaped 20 nm long projection from the virus's surface. The E2 protein is thought to be involved in pathogenesis by helping the virus enter the host cytoplasm. The E2 protein initially has 1447residues, and then a short hydrophobic sequence is cleaved. After glycosylation of the protein in the golgi, the protein is then incorporated into the new virus. There are several functional domains within the E2 protein. A 20 residue hydrophobic segment at the C-terminus anchors the protein in the lipid membrane. The rest of the protein is divided into two parts, a hydrophilic stretch that is inside the virus and a cysteine rich stretch that are possibly fatty acylation sites. The E1 protein is mostly embedded in the lipid envelop and hence plays an essential role in virus architecture. The E1 protein is postulated to interact with the lymphocyte membrane, which leads to the induction of IFN-coding genes. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Transmissible gastroenteritis coronavirus」の詳細全文を読む スポンサード リンク
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