Influence of expression and cis-acting sequences from avian leukosis viruses (ALVs) on stability of (ALV)-based retrovirus vectors.
Defective avian leukosis virus (ALV)-based vectors expressing the neo and LacZ genes were constructed under the control of cis-acting elements originated from 4 avian retroviruses: avian erythroblastosis virus (AEV), Rous associated viruses 1 (RAV-1) and 2 (RAV-2), and the Schmidt Ruppin strain of Rous sarcoma virus subgroup D (SR-RSV-D). We used these vectors to study the long-term stability of beta-galactosidase expression (encoded by the LacZ gene) in a permanent cell line from quail fibroblasts (QT6). Infection of the immortalized QT6 cell line with these vectors resulted in unstable beta-galactosidase expression. We determined whether this instability of provirus expression was correlated with: (1) presence of G418 selection; (2) deletion in the proviral genome; (3) hypermethylation of the proviral genome; (4) position of the neo and LacZ genes in the proviral genome; and (5) the transcriptional activity of the long terminal repeat (LTR) elements of proviral vectors. We observed that G418 selection pressure applied to infected QT6 cells lead to a more stable LacZ gene expression. Moreover, our results suggest a correlation between the stability of proviral gene expression and the level of gene expression driven by the LTR elements and depending on the strain origin of these.
Molina
R M
RM
Laboratoire de biologie cellulaire et moléculaire, UMR 106, Université Claude-Bernard Lyon I, Villeurbanne, France.
Chebloune
Y
Y
Verdier
G
G
Legras
C
C
D001355:Alpharetrovirus / Q000235:genetics*; D000818:Animals; D001354:Avian Leukosis Virus / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D005354:Fibrosarcoma / Q000139:chemically induced / Q000473:pathology; D015967:Gene Expression Regulation, Viral; D005822:Genetic Vectors; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D014407:Tumor Cells, Cultured / Q000201:enzymology; D001616:beta-Galactosidase / Q000235:genetics
D001616:beta-Galactosidase