ORCID Profile
0000-0003-3290-6627
Current Organisation
University of Oxford
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Publisher: Elsevier BV
Date: 2019
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-1999
DOI: 10.1097/00042560-199909010-00012
Abstract: A prospective clinical study of 20 initially asymptomatic HTLV-I-seropositive carriers was commenced in 1991 to determine the natural history of the infection in relation to HTLV-I proviral load, immune responses, and lymphocyte phenotype. Proviral load varied widely between carriers but was relatively constant within an in idual over time. The lymphocyte phenotype and prevalence of activated lymphocytes were not predictive of disease and the magnitude of the cytotoxic T-lymphocyte response to HTLV-I was independent of proviral load. Incident conditions, some related to HTLV-I infection, including a case of HTLV-I-associated myelopathy (HAM), were documented in 9 carriers. Development of myelopathy and uveitis was associated with high peripheral blood HTLV-I proviral load that predated symptoms. Persistently high proviral load appears to predate the development of HTLV-I-associated inflammation in neuro-ophthalmic tissue.
Publisher: Elsevier BV
Date: 1995
Publisher: International Union of Crystallography (IUCr)
Date: 19-09-2006
DOI: 10.1107/S0907444906030034
Abstract: Epstein–Barr virus is a herpesvirus that causes infectious mononucleosis, carcinomas and immunoproliferative disease. Its genome encodes 86 proteins, which provided targets for a structural genomics project. After updating the annotation of the genome, 23 open reading frames were chosen for expression in Escherichia coli , initially selecting for those with known enzyme activity and then supplementing this set based on a series of predicted properties, in particular secondary structure. The major obstacle turned out to be poor expression and low solubility. Surprisingly, this could not be overcome by modifications of the constructs, changes of expression temperature or strain or renaturation. Of the eight soluble proteins, five were crystallized using robotic nanolitre-drop crystallization trials, which led to four solved structures. Although these results depended on in idual treatment rather than standardized protocols, a high-throughput miniaturized crystallization screening protocol was a key component of success with these difficult proteins.
Publisher: Elsevier BV
Date: 08-2011
Publisher: Elsevier BV
Date: 10-1997
Abstract: Naturally occurring mutations in Human T-cell Leukemia Virus Type 1 (HTLV-1) Tax protein lead to loss of recognition by cytotoxic T-lymphocytes. Most of these mutations also abolish or severely impair the transactivation function of Tax. Ninety percent of the rex gene, which encodes the viral regulator of mRNA splicing (Rex), overlaps with the tax gene. In this paper, we report that four previously described point mutations in tax that abolished CTL recognition and activity did not alter either the dimerisation function or the ability to export viral mRNA of the corresponding Rex proteins. Rex proteins containing two other amino acid changes were likewise functional. However, five Rex deletion mutants, predominantly but not exclusively found in HAM/TSP patients, had all lost these functions. We conclude that, although the Tax protein is subject to strong CTL-mediated selection, there are stronger functional constraints on amino acid variation in Rex. This may limit the variation in the tax/rex nucleotide sequence which results in immune evasion.
Publisher: American Society for Microbiology
Date: 15-11-2001
DOI: 10.1128/JVI.75.22.11106-11115.2001
Abstract: The human T-cell leukemia virus type 1 (HTLV-1) Tax protein activates the HTLV-1 long terminal repeat and key regulatory proteins involved in inflammation, activation, and proliferation and may induce cell transformation. Tax is also the immunodominant target antigen for cytotoxic T cells in HTLV-1 infection. We found that Tax bound to assembled nuclear proteasomes, but Tax could not be detected in the cytoplasm. Confocal microscopy revealed a partial colocalization of Tax with nuclear proteasomes. As Tax translocated into the nucleus very quickly after synthesis, this process probably takes place prior to and independent of proteasome association. Tax mutants revealed that both the Tax N and C termini play a role in proteasome binding. We also found that proteasomes from Tax-transfected cells had enhanced proteolytic activity on prototypic peptide substrates. This effect was not due to the induction of the LMP2 and LMP7 proteasome subunits. Furthermore, Tax appeared to be a long-lived protein, with a half-life of around 15 h. These data suggest that the association of Tax with the proteasome and the enhanced proteolytic activity do not target Tax for rapid degradation and may not determine its immunodominance.
Publisher: Wiley
Date: 12-1984
DOI: 10.1111/J.1365-3083.1984.TB01035.X
Abstract: After 3-5 days of in vitro culture, peritoneal cells from untreated C3H mice produce autoantibodies specific for autoantigens in the membranes of mouse erythrocytes. The autoantigens are exposed in vitro by treating mouse erythrocytes with the proteolytic enzyme bromelain. Limiting-dilution cell culture techniques were used to determine the frequency of the autoreactive B cells. Cells were cultured in Terasaki trays at 10-200 cells/well. Autoantibody production was assayed with an in situ plaque-forming cell (PFC) assay. On average, one autoantibody precursor cell was detected for every 150-200 peritoneal cells cultured. This precursor frequency was increased to 1 in 50 by the addition of lipopolysaccharide (LPS) and dextran sulphate (DS) to the culture medium. The addition of a culture supernatant from an EL4 lymphoma subline also induced a high proportion of the peritoneal cells to secrete autoantibodies. However, it was not possible to determine the frequency of PFC accurately because at limiting numbers of peritoneal cells the effects of EL4 affected more than one limiting variable. Significant cell ision was observed in cultures to which LPS/DS had been added, in contrast to untreated cultures to which EL4 supernatant was added. The results show that high numbers of autoreactive B cells committed to self antigens are present in the peritoneal cavity and that these cells under the influence of appropriate cytokines can differentiate in vitro, even without proliferation, into autoantibody secretors. The cell type or types releasing the cytokines remain to be identified.
Publisher: Mary Ann Liebert Inc
Date: 03-1995
Abstract: tax gene expression in a family cluster of three HTLV-I-infected asymptomatic in iduals was investigated. Two carriers had normal tax mRNA, Tax-specific humoral antibody, and cell-mediated immune (CMI) response. In one carrier who had only weak Tax-specific humoral and no Tax-specific CMI response, an abnormal Tax-related mRNA product was detected. This product was sequenced and found to consist of two exons derived from the LTR gag and pX regions. The abnormal mRNA has an ORF predicting a 17-kDa protein, the translation of which is initiated in the first exon. The presence of this protein, of antibody to it, and of its function remain to be elucidated.
Publisher: Rockefeller University Press
Date: 03-02-1997
Abstract: The structurally related T cell surface molecules CD28 and CTLA-4 interact with cell surface ligands CD80 (B7-1) and CD86 (B7-2) on antigen-presenting cells (APC) and modulate T cell antigen recognition. Preliminary reports have suggested that CD80 binds CTLA-4 and CD28 with affinities (Kd values ∼12 and ∼200 nM, respectively) that are high when compared with other molecular interactions that contribute to T cell–APC recognition. In the present study, we use surface plasmon resonance to measure the affinity and kinetics of CD80 binding to CD28 and CTLA-4. At 37°C, soluble recombinant CD80 bound to CTLA-4 and CD28 with Kd values of 0.42 and 4 μM, respectively. Kinetic analysis indicated that these low affinities were the result of very fast dissociation rate constants (koff) sCD80 dissociated from CD28 and CTLA-4 with koff values of ⩾1.6 and ⩾0.43 s−1, respectively. Such rapid binding kinetics have also been reported for the T cell adhesion molecule CD2 and may be necessary to accommodate dynamic T cell–APC contacts and to facilitate scanning of APC for antigen.
Publisher: Springer Science and Business Media LLC
Date: 02-06-1994
DOI: 10.1038/369403A0
Abstract: Most asymptomatic in iduals infected with HIV-1 have a cytotoxic T lymphocyte (CTL) response to the virus Gag proteins which can be demonstrated in vitro. Epitopes have been mapped in p17 Gag and p24 Gag restricted by HLA-B8 (p17-3 and p24-13) and -B27 (p24-14). Viruses isolated from patients who make CTL responses to these peptides vary within the genetic sequences encoding these epitopes and some mutations lead to reduction in killing activity in vitro. This was attributed to either failure of the variant epitope to bind major histocompatibility complex class I or failure of T-cell receptors to bind the presented peptide. But peptide variants of class I-restricted epitopes cause 'antagonism', that is, the presence of a variant epitope (in the form of peptide) inhibits normal lysis of targets presenting the original epitope. This mirrors similar findings in class II-restricted systems. Here we report that naturally occurring variant forms of p17-3, p24-13 and p24-14 may cause antagonism of CTL lines derived from the same in iduals. The effect is present if the epitopes are derived from synthetic peptides and when they are processed from full-length proteins expressed by either recombinant vaccinia constructs or replicating HIV.
Publisher: Oxford University Press (OUP)
Date: 05-1994
Publisher: Springer Science and Business Media LLC
Date: 30-01-2008
DOI: 10.1038/NMETH.F.202
Publisher: Microbiology Society
Date: 09-1994
DOI: 10.1099/0022-1317-75-9-2233
Abstract: Human T cell leukaemia virus type 1 (HTLV-1) protease (PR14) was expressed in bacteria and purified by gel filtration. A continuous spectrophotometric assay was used to measure the kinetic parameters of substrate hydrolysis by PR14. Several peptide substrates containing HTLV-1 sequences known to be cleaved by PR14 were used. Cleavage analysis showed that the affinity with which PR14 binds these substrates is higher than that previously reported for HTLV-1 Gag peptides. Also, the affinities of peptides containing the sites involved in autocleavage of protease from its precursor are higher than for the peptides containing sites required for structural protein maturation. This suggests that the autocatalysis of protease from its own precursor has priority over other cleavage reactions and supports similar observations of an ordered hierarchy of processing events by retroviral proteases. As the N- and C-terminal regions of retroviral aspartic proteases are known to contribute to stability of the dimer by forming antiparallel beta-strands, short peptides corresponding to these terminal sequences of HTLV-1 protease were tested for their ability to inhibit cleavage of substrates by PR14. Inhibition was seen with a C-terminal peptide corresponding exactly to the C-terminal 11 amino acids of the processed PR14, whereas a peptide containing a sequence situated further from the C terminus was less effective. An inhibitor of the protease of human immunodeficiency virus type 1, Ro 31-8959, was found to be a poor inhibitor of PR14.
Publisher: Elsevier BV
Date: 08-2011
Publisher: Wiley
Date: 05-1986
DOI: 10.1111/J.1365-3083.1986.TB01989.X
Abstract: Peritoneal cells from untreated mice secrete autoantibodies after 3-4 days of in vitro culture, although the cells do not ide. Here, peritoneal cells enriched for B cells to contain 95% surface Ig-bearing cells, did not secrete autoantibodies after 3 days of in vitro culture unless plastic-adherent cells derived from the peritoneal cavity were cultured with the B cells. Cell-free media, taken from peritoneal adherent cells that had been cultured for 3 days in vitro, when added a final concentration of 50% in fresh culture medium to purified B cells, substituted for the presence of accessory cells. In contrast to cultures of unfractionated peritoneal cells, little increase in precursor frequency was detected when enriched B cells were cultured in the presence of LPS/DXS. However, the addition of adherent cells, supernatants derived from adherent cells, or cytokines produced by a T-cell hybrid EL4, resulted in an increased precursor frequency when LPS/DXS was added to the culture medium. Three macrophage cell lines, P388-D1, J774, and PU-5-IR, when added to purified B cells. augmented the autoantibody precursor frequency detected in vitro. This is strong evidence that potentially autoreactive B cells require one or more types of accessory cells in order to differentiate into autoantibody secretors during culture in vitro. Further, the results provide indirect evidence that interleukin 1 may be a crucial molecule in the differentiation of B cells.
Publisher: Mary Ann Liebert Inc
Date: 11-2000
DOI: 10.1089/08892220050193227
Abstract: Infection with human T cell leukemia virus type 1 is detected by screening programs and contact follow-up procedures. Where chronic infection results in overt pathology, this is treated largely symptomatically and control of transmission relies on physical and educational constraints. The poor infectious transmission rate of HTLV-1 has long been described but to date has not been exploited in preventative measures to combat the spread of the virus. We undertook to investigate some of the molecular steps involved in HTLV-1 cell-cell fusion, the main mechanism of transmission. We showed that poor transmission may relate in part to an inefficiency in adopting and maintaining a fusion competent conformation of the HTLV-1 envelope TM protein. In cell-cell fusion, this deficiency can be complemented by accessory molecules on both infected and target cells that stabilize the envelope/receptor interaction. In virion-cell fusion, this is less likely, leading to an inefficient interaction and poor infectious transmission by cell-free virus. A discussion of the accessory molecules involved in HTLV-1 fusion is presented. This weak envelope-dependent interaction with target cells in the host can be potently disrupted by peptides that destabilize the TM protein structure and significantly inhibit HTLV-1 fusion. These observations may be useful in the design of therapeutic agents to prevent HTLV-1 transmission.
Publisher: Elsevier BV
Date: 03-1996
Abstract: The cytotoxic T-lymphocyte (CTL) response to HTLV-1 is directed mainly against the Tax protein. Circulating, activated Tax-specific CTL can be found in a majority of healthy carriers and patients with the HTLV-1-associated disease tropical spastic paraparesis (HAM/TSP). In this study we present data on the Tax-specific CTL response of 26 HTLV-1 carriers, including 10 newly recruited subjects. Rex-specific CTL were not found in any subjects investigated. Activated and memory CTL responses were determined separately in 4 healthy carriers, 3 HAM/TSP patients, and 1 "seronegative HAM/TSP." In all subjects, the mean frequency of peptide-specific memory cells per epitope (1/1307) was high. There was no significant difference in mean memory CTL frequency per epitope or in the proportion of subjects with activated CTL between healthy carriers and HAM/TSP patients. One in idual with HAM/TSP had an unusually high frequency response to two peptides, suggesting immunodominance of epitope recognition in this in idual. We conclude that the magnitude and components of the HLTV-1-specific CTL response do not differ between healthy carriers and HAM/TSP patients. These data do not support a specific CTL-mediated component in the pathogenesis of HAM/TSP.
Publisher: Elsevier BV
Date: 03-1997
DOI: 10.1016/S0966-842X(97)87502-6
Abstract: We developed supramolecular hyaluronate (HA) hydrogels to encapsulate genetically engineered mesenchymal stem cells (MSCs) for the treatment of limb ischemia.
Publisher: Oxford University Press (OUP)
Date: 04-1994
Publisher: Oxford University Press (OUP)
Date: 1999
DOI: 10.1086/314576
Publisher: Elsevier BV
Date: 04-1987
DOI: 10.1016/0165-2478(87)90014-9
Abstract: Some established techniques for B-cell enrichment include azide in the media. Here, B-cells were enriched using a technique which transiently exposed the cells of 15 mM sodium azide. After 3-4 days in culture, the precursor frequency of autoantibody-secreting cells in this population was 0.113%. In contrast, when B-cells were enriched using a technique which eliminated their exposure to sodium azide, the number of autoantibody-secreting precursor cells detected in cultures was increased up to 20-fold. Therefore, it is concluded that transient exposure to azide affects functional activities of B-cells in vitro.
Publisher: Elsevier BV
Date: 06-1992
DOI: 10.1016/0042-6822(92)90517-S
Abstract: In human T cell lymphoma/leukemia virus (HTLV-1)-infected people with tropical spastic paraparesis (TSP), there are activated HTLV-1-specific cytotoxic T lymphocytes (CTL) in the circulation and lymphocytic infiltrates in spinal cord lesions that are rich in CD8+ T cells. These observations suggest a role for virus-specific CTL in the pathogenesis of TSP. We have examined the anti-HTLV-1 cytotoxic activity of freshly isolated CD8+ T cells from peripheral blood lymphocytes of eight subjects seropositive for HTLV-1. Four of five subjects with TSP had circulating activated anti-Tax CTL. However, two of three seropositive subjects without TSP also had activated anti-Tax CTL. These observations show that such activated CTL are not confined to patients with TSP and raise some uncertainty about their significance in the pathogenesis of the disease. In cultures of CD8+ T cells from two TSP subjects, we detected CTL with other HTLV-1 specificities, without exogenous antigenic stimulation. A CTL epitope in the middle region of Tax and one in the C terminus of Pol have been mapped at the peptide level and the HLA Class 1 molecules restricting their recognition have been defined.
Publisher: Elsevier BV
Date: 08-2011
Publisher: Springer Science and Business Media LLC
Date: 09-1999
DOI: 10.1038/43766
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2019
End Date: 2021
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