Retroviruses containing

Zinc-finger proteins are also possible targets for bicyclams. All nu-cleocapsid proteins of known strains of retroviruses contain one or two copies of an invariant sequence, Cys-X2-Cys-X4-His-X4-Cys. Proteins with this sequence bind zinc stoichiometrically with dissociation constants of ca. 10-12M (377). Under physiological conditions, a 10-fold excess of EDTA removes only 50% of zinc from the zinc finger domain of HIV-1 nucleocapsid protein (378). 

The Clonetics cell line from Cambrex Bio Science represents a cultured human corneal epithelial model (order no. CMS-2015 Cambrex Bio Science, Walkersville, MD). The culture model was generated by isolation of cells from normal human corneal tissues. The cells were then infected with an amphotropic recombinant retrovirus containing HPV-16 E6/E7 genes to extend the useful cell life span. The Clonetics cell model is a very recent entry into the immortalized corneal cell line field, but it has been proved to be useful for toxicity testing as well as in vitro drug permeation studies so far. Because of its very recent introduction, further examinations have to be undertaken to... 

The term oncogene was coined in association with the search for the tumor-causing principle in retroviruses. Retroviruses contain RNA as the genetic material and can transcribe RNA into DNA with the help of the virus s own enzyme reverse transcriptase. The DNA form of retroviruses can integrate into the DNA of the host cell and, during cell division, is passed on to the daughter cells as a provirus. From the provirus, viral RNA and complete virus particles may be formed. 

Production of a Replication-Incompetent Retrovirus Containing the Luciferase Gene... 

Retroviruses contain RNA as their genetic material, a. The retroviral RNA serves as a template for synthesis of DNA by... 

Some retroviruses contain cancer-causing genes (oncogenes), and cells Infected by such retroviruses are oncogenically transformed into tumor cells. Studies of oncogenic retroviruses (mostly viruses of birds and mice) have revealed a great deal about the processes that lead to transformation of a normal cell into a cancer cell (Chapter 23). 

Oncogenic retroviruses contain additional gene sequences, some of which replace part of the viral genome. A nononcogenic retrovirus typically contains three genes called gag-pol-env, flanked by the regulatory sequences found in the long terminal repeats (LTR). 

In most organisms RNA is made from their DNA. Some viruses, called retroviruses, contain RNA as their primary genetic material, for example, the AIDS vims and poliovims. 

Eychene, A. Marx, M. Dezelee, R Calothy, G. Complete nucleotide sequence of ICIO, a retrovirus containing the Rmil oncogene transduced in chicken neuroretina cells infected with avian retrovirus RAV-1. Nucleic Acids Res., 17, 1250 (1989)... 

In 1985 Toh et recognized a sequence in the Rous sarcoma virus (RSV) genome that resembled that of the Asp-Thr-Gly motif of aspartic proteinases, and a similar sequence was subsequently identified in HIV. This led to the suggestion that retroviruses contained a dimer which resembled the putative dimeric ancestor of the pepsin-like aspartic proteinases.The analogy, supported by observations that an HTV proteinase was sensistive to pepstatin, led to interest in the development of HIV proteinase inhibitors. It was later noted that HIV requires a specific protease for the maturation of its components and therefore inhibition of this protease could represent a therapeutic approach to the treatment of AIDs. 

Ans. Retroviruses are RNA viruses that reproduce through the intermediate formation of DNA. The retrovirus contains genetic information for the synthesis of the enzyme reverse tramcriptase. Reverse transcriptase, synthesized using the host cell s mechanism for protein synthesis, directs the synthesis of viral DNA from viral RNA. Subsequently, the host reproduces the viral RNA using the DNA as a template. The retroviruses include HIV and cancer-causing viruses (oncogenic viruses). 

Wei C M, Gibson M, Spear P G, et al. (1981). Construction and isolation of a transmissible retrovirus containing the src gene of Harvey murine sarcoma virus and the thymidine kinase gene of herpes simplex virus type 1. J. Virol. 39 935-944. 

Kerr, W. G., Nolan, G. R, Serafini, A. T., and Herzenberg, L. A. (1989) Transcriptionally defective retroviruses containing lacZ for the in situ detection of endogenous genes and developmentally regulated chromatin. Cold Spring Harbor Symp. Quant. Biol. 54,767-776. 

Fig. 22.1. Protocol schematic for ex vivo hepatic gene therapy. The lateral segment of the patient s liver was removed by a subcostal incision, and a Hickman catheter was placed by sacrificing the inferior mesenteric vein. The liver specimen (-250 gm) was then perfused with coUagenase to release hepa-tocytes (-3 billion) which were then divided into 800 culture dishes. Two days later, a retrovirus containing the sequence for the LDL receptor was added to the culture media. The hepa-tocytes were harvested 12-18 hrs later and divided into three aliquots. Each aliquot was infused slowly (2 cc/min) back into the patient s portal circulation using the Hickman catheter. Adapted from Grossman [8]...

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