Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019158 (hepatitis)
 30,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The coronavirus mouse hepatitis virus-A59 (MHV-A59) encodes a serine-like proteinase (3C-like proteinase or 3CLpro) in ORF 1a of gene 1 between nucleotides 10,209 and 11,114. We previously have demonstrated that proteins expressed in vitro from a cDNA clone of the 3CLpro region possess proteinase activity, and that the proteinase is able to cleave substrate in trans. We sought to determine if the 27-kDa in vitro cleavage product (p27) was an active form of the 3CLpro and whether this was consistent with the 3CLpro expressed in virus-infected cells. Antibodies directed against the 3CLpro domain detected 27-kDa MHV proteins in vitro and in MHV-A59-infected cells. The 27-kDa proteins were able to cleave substrate in trans without other protein cofactors or supplemental membranes, and the p27 proteinase activity was retained after purification by immunoprecipitation and gel electrophoresis. When p27 was expressed in vitro with portions of the amino-and carboxy-terminal flanking domains (MP1 and MP2), p27 was not liberated by cls cleavage. The proteolytic activity of the 27-kDa proteins was inhibited by a variety of cysteine and serine proteinase inhibitors, and was eliminated by the cysteine proteinase inhibitor E64d. These results indicate that the 27-kDa protein is a mature proteinase in MHV-A59-infected cells, and that appropriate processing of this molecule occurs in vitro.
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PMID:Intracellular and in vitro-translated 27-kDa proteins contain the 3C-like proteinase activity of the coronavirus MHV-A59. 880 21

The replication complexes (RCs) of positive-stranded RNA viruses are intimately associated with cellular membranes. To investigate membrane alterations and to characterize the RC of mouse hepatitis virus (MHV), we performed biochemical and ultrastructural studies using MHV-infected cells. Biochemical fractionation showed that all 10 of the MHV gene 1 polyprotein products examined pelleted with the membrane fraction, consistent with membrane association of the RC. Furthermore, MHV gene 1 products p290, p210, and p150 and the p150 cleavage product membrane protein 1 (MP1, also called p44) were resistant to extraction with Triton X-114, indicating that they are integral membrane proteins. The ultrastructural analysis revealed double-membrane vesicles (DMVs) in the cytoplasm of MHV-infected cells. The DMVs were found either as separate entities or as small clusters of vesicles. To determine whether MHV proteins and viral RNA were associated with the DMVs, we performed immunocytochemistry electron microscopy (IEM). We found that the DMVs were labeled using an antiserum directed against proteins derived from open reading frame 1a of MHV. By electron microscopy in situ hybridization (ISH) using MHV-specific RNA probes, DMVs were highly labeled for both gene 1 and gene 7 sequences. By combined ISH and IEM, positive-stranded RNA and viral proteins localized to the same DMVs. Finally, viral RNA synthesis was detected by labeling with 5-bromouridine 5'-triphosphate. Newly synthesized viral RNA was found to be associated with the DMVs. We conclude from these data that the DMVs carry the MHV RNA replication complex and are the site of MHV RNA synthesis.
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PMID:RNA replication of mouse hepatitis virus takes place at double-membrane vesicles. 1190 9