9-30_11_AM_HIV - Retroviruses & Human...

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Unformatted text preview: Retroviruses & Human Immunodeficiency Virus (HIV) Unique Features of Retroviruses Key Features A. Human viruses are associated with tumors, leukemias, and immunodeficiencies. B. Common genetic organization and strategy - major differences lie in regulatory complexity. C. Genome consists of 2 copies of (+) stranded RNA. D. RNA converted to DNA (reverse transcription) by a bizarre mechanism followed by chromosomal integration. E. Integrated DNA co-linear with viral DNA. Three Subfamilies of Human retroviruses Oncovirinae (HTLV-1, HTLV-2, and HTLV-5) include members that can immortalize and transform target cells Lentivirinae (HIV-1 and HIV-2) include members that are slow viruses and associated with neurologic and immunosuppressive disease Spumavirinae (Human foamy virus) not associated with human disease Oncovirinae Transformation Oncovirinae can immortalize and transform cells. They are fast acting and cause sarcomas and leukemias through incorporated cellular genes (protooncogenes) which cause dis-regulation of cell growth. They can transform cells in vitro. At least 35 different protooncogenes have been identified which include growth hormones, growth hormone receptors, protein kinases, GTP-binding proteins and nuclear DNA binding proteins. Leukemiaviruses A sub-class of oncoviruses that cause cancer by up-regulating cell growth Some oncoviruses, such as HTLV, cannot transform cells in vitro they produce cancer (in vivo) after a long latency period and promote unregulated growth indirectly rather than through the presence of a viral encoded oncogene. T-cell leukemias are usually monoclonal. HIV Kills cells rather than immortalizing them HIV is a slow cytocidal virus with exquisite tropism for CD4+ expressing cells and macrophages. It is the loss of CD4+ cells which destroys helper and delayed type hypersensitivity functions of the immune response. Reverse Transcribing Viruses - HIV Figure 59-1 Primate lentiviruses have a distinct morphology and can induce syncytia during productive infections. A: Electron micrograph showing a single HIV-1 particle in the process of budding from an infected cultured human PBMC, and several mature virions containing the characteristic conical/bullet-shaped nucleoid (*100,000). (Photomicrograph kindly provided by Dr. Jan Orenstein.) Fields Virology 4 th edition, 2002, Chapter 59, Lippincott, Williams and Wilkins, 2002 Fig....
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This note was uploaded on 07/02/2011 for the course MMC 6500 taught by Professor Gulig during the Spring '11 term at University of Florida.

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9-30_11_AM_HIV - Retroviruses & Human...

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