The left-end and right-end origins of minute virus of mice DNA differ in their capacity to direct episomal amplification and integration in vivo

Previously it was shown that a 53-nucleotide viral replication origin, deri ved from the left-end (3') telomere of minute virus of mice (MVM) DNA, dire cted integration of infecting MVM genomes into an Epstein-Barr virus (EBV)- based episome in cell culture. Integration depended upon the presence, in t he episome, of a functional origin sequence which could be nicked by NS1, t he viral initiator protein. Here we extend our studies to the genomic right -end (5') origin and report that three 131- to 135-nucleotide right-end ori gin sequences failed to target MVM episomal integration even though the sam e sequences were functional in NS1-driven DNA replication assays in vitro. Additionally, we observed amplification of episomal DNA in response to MVM infection in cell lines harboring episomes which directed integration, but not in cell lines containing episomes which did not direct integration, inc luding those with inserts of the MVM right-end origin. (C) 2001 Academic Pr ess.