Retroviruses immunodeficiency virus

The viruses responsible for AIDS are human immunodeficiency virus 1 and 2 (HIV 1 and HIV 2) Both are retroviruses, meaning that their genetic material is RNA rather than DNA HI Vs require a host cell to reproduce and the hosts m humans are the T4 lymphocytes which are the cells primarily responsible for inducing the immune system to respond when provoked The HIV penetrates the cell wall of a T4 lymphocyte and deposits both its RNA and an enzyme called reverse transcriptase inside There the reverse transcriptase catalyzes the formation of a DNA strand that is complementary to the viral RNA The transcribed DNA then serves as the template from which the host lymphocyte produces copies of the virus which then leave the host to infect other T4 cells In the course of HIV reproduction the ability of the T4 lymphocyte to reproduce Itself IS compromised As the number of T4 cells decrease so does the body s ability to combat infections... 

Najera I, Richman DD, Olivares I, Rojas JM, Peinado MA, Perucho M, Najera R, Lopez GaHndez C (1994) Natural occurrence of drug resistance mutations in the reverse transcriptase of human immunodeficiency virus type 1 isolates. AIDS Res Hum Retroviruses 10 1479-1488 Nijhuis M, Boucher CAB, Schipper R Leitner T, Schuurman R, Albert J (1998) Stochastic processes strongly influence HIV-1 evolution during suboptimal protease inhibitor therapy. Proc Natl Acad Sci USA 95 14441-14446... 

Lores P, Boucher V, Mackay C, Pla M, Von Boehmer H, Jami J, Barre-Sinoussi E, Weill JC (1992) Expression of human CD4 in transgenic mice does not confer sensitivity to human immunodeficiency virus infection. AIDS Res Hum Retroviruses 8 2063-2071 Maddon PJ, Dalgleish AG, McDougal JS, Clapham PR, Weiss RA, Axel R (1986) The T4 gene encodes the AIDS virus receptor and is expressed in the immune system and the brain. Cell 47 333-348... 

Harbol AW, Liesveld JL, Simpson-Haidaiis PJ, Abboud CN (1994) Mechanisms of cytopenia in human immunodeficiency virus infection. Blood Rev 8(4) 241-251 Harris RS, Sheehy AM, Craig HM, Malim MH, Neuberger MS (2003) DNA deamination not just a trigger for antibody diversification but also a mechanism for defense against retroviruses. Nat Immunol 4(7) 641-643... 

Lawrence DM, Durham LC, Schwartz L, Seth P, Marie D, Major EO (2004) Human immunodeficiency virus type 1 infection of human brain-derived progenitor cells. J Virol 78(14) 7319-7328 Li XY, Guo F, Zhang L, Kleiman L, Cen S (2007) APOBEC3G inhibits DNA strand transfer during HIV-1 reverse transcription. J Biol Chem 282(44) 32065-32074 Lin J, Cullen BR (2007) Analysis of the interaction of primate retroviruses with the human RNA interference machinery. J Virol 81(22) 12218-12226 Liu JO (2005) The yins of T cell activation. Sci STKE 2005(265) rel... 

Human immunodeficiency virus (HIV) Differs from other retroviruses in that the core is cone-shaped rather than icosahedral HIV is transmitted from person to person via blood or genital secretions. The principal target for the virus is the CD4+ T-lymphocyte cells. Depletion of these cells induces immunodeficiency... 

Human immunodeficiency virus (HIV) is a retrovirus, i.e. its RNA is converted in human cells by the en me reverse transcriptase to DNA which is incorporated into the human genome and is responsible for producing new HIV particles. Zidovudine (azidothymidine, AZT Fig. 5.22F) is a stmctural analogue of thymidine (Fig. 5.22A) and is used to treat AIDS patients. Zidovudine is converted in both infected and uninfected cells to the mono-, di- and eventually triphosphate derivatives. Zidovudine triphosphate, the aetive form, is a potent inhibitor of HIV replication, being mistaken for thymidine by reverse transeriptase. Premature ehain termination of viral DNA ensues. However, AZT is relatively toxic because, as pointed out above, it is converted to the triphosphate by eellular enzymes and is thus also aetivated in uninfected cells. 

Moore JP, Kitchen SG, Pugach P, Zack JA. The CCR5 and CXCR4 coreceptors—central to understanding the transmission and pathogenesis of human immunodeficiency virus type 1 infection. AIDS Res Hum Retroviruses 2004 20(1) 111-126. 

PMEA and its congeners are more effective in vivo than could be predicted from their in vitro potency. While less potent as an antiretrovirus agent than AZT in vitro, PMEA proved clearly superior to AZT when the two drugs were compared for their effectiveness in vivo, in mice infected with murine Moloney sarcoma virus [51,52]. PMEA was also shown to be effective against various other retrovirus infections, including Friend leukemia virus (FLV), Rauscher leukemia virus (RLV), and LP-BM5 (murine AIDS) virus infection in mice, feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV) infection in cats, and SIV infection in macaque (rhesus) monkeys (for review, see Ref. 53). In the latter model [54], again PMEA proved far superior to AZT in suppressing several parameters of the disease. 

Balzarini J, Hao Z, Herdewijn P, Johns DG, De Clercq E. Intracellular metabolism and mechanism of anti-retrovirus action of 9-(2-phosphonylme-thoxyethyl)adenine, a potent anti-human immunodeficiency virus compound. Proc Natl Acad Sci USA 1991 88 1499-1503. 

The human immunodeficiency virus HIV is a retrovirus (Table 6), so called because this ss RNA virus contains a pol gene that codes for a reverse transcrip-... 

The genetic material in a retrovirus is RNA not DNA. The best known retrovirus is the human immunodeficiency virus (HIV) which infects lymphocytes and hence interferes with the immune system, giving rise to the disease AIDS. Once the virus infects its host, it converts its RNA into DNA by an enzyme known as reverse transcriptase and the DNA is then inserted into the genome of the host cell (in this case the lymphocyte) ... 

Human immunodeficiency virus (HIV) is a single-stranded RNA retrovirus that causes acquired immunodeficiency syndrome (AIDS), a condition in which individuals are at increased risk for developing certain infections and malignancies. The virus is found in two major forms HIV-1, the most prevalent worldwide, and HIV-2, the most common in western Africa. More than 22 million people have died of HIV infection, and 40 million are believed to be infected worldwide. AIDS epidemics threaten populations in sub-Saharan Africa, Southeast Asia, Central and South America, and Russia. In the United States about 450,000 deaths have occurred and another 900,000 people are estimated to carry the virus. Although the development of new drugs, complex multidrug regimens, and behavioral modification have done much to combat the spread of HIV in-... 

Exploded view of the human immunodeficiency virus. It is an RNA (retrovirus) virus that contains surface proteins composed of a knoblike glycoprotein (gpl20) linked to a transmembrane stalk (gp41). These surface proteins are the infective mechanisms that allow the virus to bind to CD4 proteins of cells, such as T4 lymphocytes and monocytes. 

Retroviruses require proliferative target cells to mediate effective gene transfer. Lentiviruses, the class of retrovirus that includes human immunodeficiency virus, are an exception. They can also integrate in nondividing cells. An additional obstacle for retroviruses is the high susceptibility of the virus particle to humoral factors that ablate their gene transfer capacity. Perhaps most important, retroviruses, even when used ex vivo, pose a low but real risk of cancer. 

Matano, T., Odawara, T., Iwamoto, A., et al. (1995). Targeted infection of a retrovirus bearing a CD4-Env chimera into human cells expressing human immunodeficiency virus type 1. J. Gen Virol, 76, 3165-3169. 

Like all other retroviruses, human immunodeficiency virus type 1 (HIV-1) contains the multifunctional enzyme reverse transcriptase (RT). Retroviral RTs have a DNA polymerase activity that can use either an RNA or a DNA template and an RNase H activity. HIV-1 RT is essential for the conversion of single-stranded viral RNA into a linear double-stranded DNA that is subsequently integrated into the host cell chromosomes [1-4]. In this conversion process HIV-1 RT catalyzes the incorporation of approximately... 

The human immunodeficiency virus (HIV) is one of only a few retroviruses known to infect humans. It is estimated that approximately twenty-two million people are now infected worldwide [1]. With only a tiny number of exceptions, infection ultimately leads to the development of the lethal condition of acquired immunodeficiency syndrome, or AIDS. To date, only a handful of drugs have been shown to have any effect on the course of the disease. These are, in general, relatively ineffective at significantly prolonging life, and drug resistance develops rapidly. Equally discouraging, vaccines have not yet been developed to prevent infection. 

Research into the chemistry of template-dependent nucleic acid biosynthesis, combined with modern techniques of molecular biology, has elucidated the life cycle and structure of the human immunodeficiency virus, the retrovirus that causes AIDS. A few years after the isolation of HIV, this research resulted in the development of drugs capable of prolonging the lives of people infected by HIV. 

In 1983 the move to develop red cell substitutes intensified when it was recognized that the acquired immune deficiency syndrome (AIDS) could be transmitted by the blood-bome human immunodeficiency virus (HIV). Concern for the nation s blood supply followed. Since that time other retroviruses have been identified, efforts to screen blood not only for these agents but also for viruses that cause hepatitis have intensified, the indications for transfusion have been reevaluated, and the use of blood products has become much more efficient. More careful screening of donors, testing of all donated units, and a general awareness in the donor population have all contributed to a decreased risk from transfusion-contracted AIDS. 

Retroviruses, such as the human immunodeficiency virus, carry their genomes in the form of single-stranded RNA molecules. They use reverse transcriptase to make a DNA copy of their RNA and can integrate the copy into host cells. 

HIV-1 and other retroviruses. Because of their association with viral oncogenes (Chapter 11) and because of the human immunodeficiency virus... 

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