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J Greatorex

Publications and source records attributed to J Greatorex.

8 recordsLinked to original sources
PubMed2003

The packaging signal of simian immunodeficiency virus is upstream of the major splice donor at a distance from the RNA cap site similar to that of human immunodeficiency virus types 1 and 2.

Deletion mutation of the RNA 5' leader sequence of simian immunodeficiency virus (SIV) was used to localize the virus packaging signal. Deletion of sequences upstream of the major splice donor (SD) site produced a phenotype most consistent with a packaging defect when analysed by both RNase protection assay and RT-PCR. Sequences downstream of the SD were deleted and produced varying effects but did not affect packaging: a large downstream deletion had little effect on function, whereas a nested deletion produced a profound replication defect characterized by reduced protein production. Secondary structure analysis provided a potential explanation for this. The major packaging signal of SIV appears to be upstream of the SD in a region similar to that of human immunodeficiency virus type 2 (HIV-2) but unlike that of HIV-1; however, the packaging signal of all three viruses are at a similar distance from their respective cap sites. This conserved positioning suggests that it is more important in the virus life cycle than the position of the signal relative to the SD.

5' Untranslated Regions↗
PubMed2001

Oligonucleotide mapping of the core genomic RNA dimer linkage in human T-cell leukaemia virus type-1.

We have previously mapped the sequences required for dimerisation of the 5' leader of the human T-cell leukaemia virus type-1 (HTLV-1) genome. The smallest sequence necessary and sufficient for dimer formation, in vitro, was ascertained to be a 37 nucleotide (nt) region downstream of the splice donor and just upstream of the primer binding site. Deletion of a 32 base-pair sequence encompassing this region within the provirus was associated with a minor decrease in infectivity of the virus in an in vitro system. To further map and help elucidate the nature of the dimer linkage, we used RNA and DNA oligonucleotide competition assays to define the nucleotides involved. These experiments revealed that a 14 nt sequence containing a potential stem loop structure, formed from a palindromic sequence, is important for dimer formation. This was confirmed by the ability of this RNA sequence to form heterodimers with larger RNA transcripts from the same region, while sequences lacking this motif could not. RNA transcripts containing the reverse sequence, the same nucleotides in a random arrangement, and complementary DNA oligos, all failed to form heterodimers with the 14 nt sequence. The primary dimer initiation site of HTLV-1 has thus been located to a 14 nt palindrome containing sequence, and dimerisation is shown to be dependent on specific sense-sense RNA interactions.

Computer Simulation↗
PubMed2001

Sequences in the 5' leader of Mason-Pfizer monkey virus which affect viral particle production and genomic RNA packaging: development of MPMV packaging cell lines.

We used a series of deletion mutations in the 5' untranslated region of the prototype D type retrovirus, Mason-Pfizer Monkey Virus (MPMV), to analyse RNA encapsidation. A region was identified upstream of the major splice donor which reduced particle production but had a proportionally greater effect on RNA packaging. A small deletion downstream of the splice donor had little effect on RNA production and caused no significant packaging defect. A large deletion encompassing the end of the primer binding site down to the splice donor had a dramatic effect, disrupting viral protein synthesis. Stable cell lines were produced containing packaging-defective virus. These first-generation packaging cell lines were used to package and transfer an MPMV-based vector.

5' Untranslated Regions↗
PubMed2000

A 37 base sequence in the leader region of human T-cell leukaemia virus type I is a high affinity dimerization site but is not essential for virus replication.

Mutagenesis has demonstrated a region in the human T-cell leukaemia virus type I (HTLV-I) 5' leader RNA which, when deleted, abolishes stable RNA dimer formation in vitro. We have further mapped, using both in vitro transcribed and synthesized RNA, this site to a 37 base region, which dimerizes with high affinity. When deleted from an HTLV-I Gag-Pol-expressing plasmid which was co-transfected with an envelope protein expressor to produce virions capable of single round infection, the dimer linkage deletion did not affect viral protein production. In addition, virus infectivity was only slightly reduced, to approximately 75-80% of the wild-type.

5' Untranslated Regions↗
PubMed2000

An accessible analytical approach for investigating what happens between the rounds of a Delphi study.

The Delphi method is used to investigate consensus amongst a panel of experts using repeated rounds of a questionnaire, often in healthcare settings. However, many Delphi studies do not report any investigation into what happens to the stability of consensus or the convergence of agreement between the rounds in the study, which may be of importance. In this paper an accessible analytical approach is outlined using graphical presentations of means and standard deviations to identify what happens between rounds. For Delphi studies where the scale upon which experts are expressing their opinions can be considered to be interval, the mean will represent the group opinion whilst the standard deviation will represent the level of agreement. An example Delphi study from a healthcare setting is used to illustrate the methodology.

Attitude of Health Personnel↗
PubMed1991

Streptococci from primary isolation plates grouped by reverse passive haemagglutination.

Reverse passive haemagglutination, a novel microtitre based assay, was compared with the Streptex (Wellcome UK) latex slide agglutination kit for streptococcal grouping in a diagnostic microbiology laboratory. Three hundred and fifty two extracts from 349 consecutive primary isolation plates were assayed by both methods. Reverse passive haemagglutination gave identical grouping results for 98.0% of the 345 streptococci identified by Streptex, and the kappa coefficient of agreement between the methods for all 352 extracts tested was 0.973. Cross reactions with Listeria spp seen with Streptex were not found by reverse passive haemagglutination. In the reverse passive haemagglutination method 11 streptococci could be grouped on each 96-well plate and most reactions were stable for at least 30 minutes. Reverse passive haemagglutination is more rapid to perform than latex slide agglutination when many organisms are to be grouped, and the patterns of haemagglutination are easily recognised. If the method was taken into routine use in a diagnostic laboratory, the persistence of reverse passive haemagglutination reactions would enable grouping results to be checked for quality control purposes.

Genitalia↗
PubMed1981

A Kiwi Columbus.

Explore the source record for details and available documents.

New Zealand↗