HTLV-I trans-activator protein, Tax, is a trans-repressor of the human beta-polymerase gene
Article Abstract:
Hu man T cell leukemia virus type I (HTLV-I) is related to a particular type of adult T cell leukemia, but unlike many other retroviruses, it does not have an oncogene which directly causes the transformation of target cells. The precise mechanisms by which HTLV-I induces leukemia are not clear. Analysis of cells transformed by HTLV-I shows that the activity of the gene for beta-polymerase is repressed. Techniques of molecular biology may be used to demonstrate that this effect is due to a specific protein coded by a viral gene, the trans-activator protein, Tax. The gene for Tax was inserted into bacterial DNA so that it could be cloned. The DNA plasmids containing the Tax gene could then be used to transfect human HeLa cells, a tissue-culture line of cancer cells. When these cells were assayed, the promoter of the beta-polymerase gene was found to be repressed. Since no other viral proteins are present, and the bacterial plasmid itself has no effect, the repression of beta-polymerase is specific to Tax. Beta-polymerase plays a role in the repair of DNA within human cells, so this repression may explain not only the carcinogenic effects of HTLV-I, but also why fewer than 1 percent of people infected actually get leukemia. A second event, probably a mutation, may be necessary to actually cause leukemia, but the repression of DNA repair by the viral protein may make such an event more likely. In this light, it is worth noting that cells from adult T cell leukemia patients often have aberrant chromosomes, probably the result of unrepaired genetic damage to the host. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Science
Subject: Science and technology
ISSN: 0036-8075
Year: 1990
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A strategy for prophylactic vaccination against HIV
Article Abstract:
Strategies to develop an AIDS vaccine should be based on cell-mediated rather than antibody-mediated aspects of the immune system. In a study, 49% of uninfected individuals who had been exposed to HIV exhibited cell-mediated immunity to HIV, but only 2% of unexposed individuals showed the same response.
Publication Name: Science
Subject: Science and technology
ISSN: 0036-8075
Year: 1993
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Attenuated retrovirus vaccines and AIDS
Article Abstract:
Research on macaques found that a deletion mutant of simian immunodeficiency virus used as a vaccine in adults caused AIDS in newborn macaques. Other research on simian AIDS and the implications of the research for human AIDS vaccination are discussed.
Publication Name: Science
Subject: Science and technology
ISSN: 0036-8075
Year: 1995
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