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Q L Choo

Publications and source records attributed to Q L Choo.

62 records · Page 4Linked to original sources
PubMed1989

Isolation of a cDNA clone derived from a blood-borne non-A, non-B viral hepatitis genome.

A random-primed complementary DNA library was constructed from plasma containing the uncharacterized non-A, non-B hepatitis (NANBH) agent and screened with serum from a patient diagnosed with NANBH. A complementary DNA clone was isolated that was shown to encode an antigen associated specifically with NANBH infections. This clone is not derived from host DNA but from an RNA molecule present in NANBH infections that consists of at least 10,000 nucleotides and that is positive-stranded with respect to the encoded NANBH antigen. These data indicate that this clone is derived from the genome of the NANBH agent and are consistent with the agent being similar to the togaviridae or flaviviridae. This molecular approach should be of great value in the isolation and characterization of other unidentified infectious agents.

Animals↗
PubMed1988

A single antigenomic open reading frame of the hepatitis delta virus encodes the epitope(s) of both hepatitis delta antigen polypeptides p24 delta and p27 delta.

On the basis of the complete nucleotide sequence of the single-stranded, covalently closed circular hepatitis delta virus RNA genome (K.-S. Wang, Q.-L. Choo, A. J. Weiner, J.-H. Ou, R. C. Najarian, R. M. Thayer, G. T. Mullenbach, K. J. Denniston, J. L. Gerin, and M. Houghton, Nature [London] 323:508-514, 1986 [Author's correction, 328:456, 1987]), five long open reading frames (ORFs) encoding polypeptides containing a methionine proximal to the amino terminus were expressed in bacteria. Only polypeptides encoded by the antigenomic ORF5 cross-reacted with antisera obtained from patients with hepatitis delta virus infections. Immunological analysis of viral extracts and the recombinant ORF5 polypeptides synthesized in bacteria and yeast cells revealed that ORF5 encodes the immunogenic epitope(s) shared by both hepatitis delta viral polypeptides p27 delta and p24 delta and probably represents the complete structural gene for p27 delta and p24 delta. We also present evidence that ORF5 encodes the hepatitis delta antigen, an antigen originally found in the nuclei of hepatocytes of infected individuals (M. Rizzetto, M. G. Canese, S. Arico, O. Crivelli, F. Bonino, C. G. Trepo, and G. Verme, Gut 18:997-1003, 1977). A comparison of the primary structure of the predicted hepatitis delta antigen polypeptides with that of the core antigen of the hepatitis B virus shows that these polypeptides are very dissimilar.

Amino Acid Sequence↗
PubMed1987

Hepatitis delta (delta) cDNA clones: undetectable hybridization to nucleic acids from infectious non-A, non-B hepatitis materials and hepatitis B DNA.

Hepatitis Delta (delta) cDNA clones were hybridized to RNA extracted from livers of chimpanzees infected with the blood-borne Non-A, Non-B hepatitis (NANBH) agent(s) and to total nucleic acids extracted from chimpanzee plasma containing a high titer of these NANBH agent(s). Since no hybridization was observed, the data suggests that the hepatitis Delta viral genome is not closely related to the genome(s) of the NANB agent(s). Our studies, in which the Hepatitis B virus genomic DNA was hybridized to hepatitis Delta cDNA clones, also confirm and extend previous studies [Hoyer et al, 1983], which report a lack of detectable homology between the hepatitis Delta genome and HBV DNA.

Animals↗
PubMed1984

Structure of two related rat pancreatic trypsin genes.

A family of approximately 10 trypsin genes was detected in a rat genomic library by hybridization and in vivo recombination techniques using cloned rat pancreatic trypsin I and II cDNAs as probes. Two separate clones containing the entire trypsin I gene and most of the trypsin II gene were sequenced. Four introns split the trypsin I coding sequence. The positions of the first three introns of the trypsin II gene are identical with those in the trypsin I gene (the fourth intron was not present in the trypsin II clone). The coding regions of the two genes are 88% homologous; the 5'-noncoding regions are 92% homologous, whereas the 3'-noncoding regions share 66% identity. In contrast, the proximal 5'-flanking regions from -1 to -500 which may contain the elements controlling gene expression are less than 30% conserved overall, but segments of approximately 70% homology can be discerned in this region. Some of these sequences are homologous to sequences found in the chymotrypsin and elastase genes. More distal upstream sequences (-500 to -2500) and the intervening sequences show no evident sequence homology (less than 20%). Unique sequences containing homopolymeric purine/pyrimidine repeats are found 2.5 kilobases upstream from the start of transcription of the trypsin I gene and within the second and third introns of the trypsin II gene. The nucleotide homologies as well as the similarities of intron positions of the two trypsin genes to those of other serine protease genes clearly support an evolutionary relationship between members of this gene family.

Animals↗
PubMed1982

Vimentin and 70K neurofilament protein co-exist in embryonic neurones from spinal ganglia.

The mesenchymal intermediate filament protein vimentin and the 70K component of neurofilament were detected by two-dimensional gel electrophoresis in cultures of pure sensory and sympathetic neurones derived from chick embryos. The identities of these neuronal intermediate filament proteins were confirmed by comparison of their molecular weights, isoelectric points, and peptide patterns from limited papain digestions with those of the corresponding proteins from fibroblasts and brain, respectively. A specific antibody to vimentin stained filamentous structures and colcemid-induced coils in both neurones and associated satellite cells. In contrast, a specific antibody to the 70K neurofilament protein stained these structures solely in neurones. This neurone-specific staining, as well as its molecular weight and isoelectric point, distinguishes the 70K neurofilament protein from the 68K neurofilament associated protein described by others, which has been claimed to resemble the tubulin assembly protein.

Animals↗
PubMedDate not supplied

Structure, sequence and expression of the hepatitis delta (delta) viral genome.

Biochemical and electron microscopic data indicate that the human hepatitis delta viral agent contains a covalently closed circular and single-stranded RNA genome that has certain similarities with viroid-like agents from plants. The sequence of the viral genome (1,678 nucleotides) has been determined and an open reading frame within the complementary strand has been shown to encode an antigen that binds specifically to antisera from patients with chronic hepatitis delta viral infections.

Base Sequence↗