Sequences in the 5 ' leader of Mason-Pfizer monkey virus which affect viral particle production and genomic RNA packaging: Development of MPMV packaging cell lines

We used a series of deletion mutations in the 5' untranslated region of the prototype D type retrovirus, Mason-Pfizer Monkey Virus (MPMV), to analyse RNA encapsidation. A region was identified upstream of the major splice don or which reduced particle production but had a proportionally greater effec t on RNA packaging. A small deletion downstream of the splice donor had lit tle effect on RNA production and caused no significant packaging defect. A large deletion encompassing the end of the primer binding site down to the splice donor had a dramatic effect, disrupting viral protein synthesis. Sta ble cell lines were produced containing packaging-defective virus. These fi rst-generation packaging cell lines were used to package and transfer an MP MV-based vector. (C) 2001 Academic Press.