Avectin, a new gene therapy developed by Applied Immune Sciences,offers a simple, easy-to-manufacture method for the transfer of genesacross cell membranes, the Santa Clara, Calif. company says.The procedure, described in the April issue of Molecular and CellularBiology, involves the use of cationic liposomes to facilitate adeno-associated virus (AAV) plasmid transfections of primary and culturedcell types."This discovery enhances our position in the gene therapy area," saidJackie Cossmon, the company's director of corporate communications."This gives us the ability to get a gene into a cell in an efficient mannerand improve gene expression. It also minimizes the risk of viral sideeffects because it uses only a small section of the virus. Anotherimportant point is that this system enables the transfer of the gene intonon-dividing cells such as stem cells and lymphocytes, which isnormally very difficult."Applied Immune Sciences (NASDAQ:AISX) developed Avectin foruse in its ongoing cell and gene therapy clinical research programs, andhas applied for a patent on the composition and use of the method inhuman gene therapy protocols. The company expects to begin clinicaltrials using Avectin for T-lymphocyte therapy for AIDS and tumorvaccination for breast cancer early in 1995.The researchers, including scientists from both Applied Sciences andUCLA Medical Center, noted in their paper that in the procedure, "theAAV plasmid which contained the transgene and AAV terminal repeatsis used as a DNA vector and cationic liposomes are used as carriermolecules."They said their study "demonstrated that viruses can be replaced byliposomes and efficient expression can be attained by utilizing aconstruct which includes viral elements responsible for both efficiencyand duration . . . When the plasmid containing the essential terminalrepeats is combined with liposomes, the transfection process issimplified and high-level, long-term expression is achieved in bothdividing and non-dividing cell types, yet we avoid the complicationsinvolved with virus production."According to the researchers, this result was achieved in vivo withoutany measurable toxicity. n
-- Philippa Maister
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