Viral vectors retroviral

There is a wide variety of vectors used to deliver DNA or oligonucleotides into mammalian cells, either in vitro or in vivo. The most common vector systems are based on viral [retroviruses (9, 10), adeno-associated virus (AAV) (11), adenovirus (12, 13), herpes simplex virus (HSV) (14)] andnonviral [cationic liposomes (15,16), polymers and receptor-mediated polylysine-DNA] complexes (17). Other viral vectors that are currently under development are based on lentiviruses (18), human cytomegalovirus (CMV) (19), Epstein-Barr virus (EBV) (20), poxviruses (21), negative-strand RNA viruses (influenza virus), alphaviruses and herpesvirus saimiri (22). Also a hybrid adenoviral/retroviral vector has successfully been used for in vivo gene transduction (23). A simplified schematic representation of basic human gene therapy methods is described in Figure 13.1. 

Stable intracellular expression of transcriptionally active ribozymes can be achieved by viral vector-mediated delivery. Currently, retroviral vectors are the most commonly used in cell culture, primary cells... 

Cumulative experience from 106 monkey-years and 23 human-years of retroviral gene therapy had revealed no side-effects or malignancies. Recently, however, three monkeys used in clinical trials developed T cell lymphomas which were traced to a helper virus-contaminated retroviral vector preparation (Anderson, 1992a). Contamination of defective viral vector stocks by infectious viruses produced in helper cells was a serious problem with the early version of the helper cells. New helper cell lines which greatly reduce the probability of virus production have been developed (Miller, 1990). Eurther, it is also imperative to test the lots of vector virus preparations used in therapy for the presence of other infectious viruses. The probability... 

Retroviruses are interesting viral vectors that incorporate their RNA (through the cDNA) into the host s DNA. The viral particles are composed of a core of viral RNA, surrounded by replication enzymes, host membrane, and an outer viral glycoprotein coat.230 There are seven genera and all could conceivably be used for the display of alien proteins. Retroviral display has been recently reviewed.231... 

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