Ian's point is well taken. Standard SV40 ori will trash COS cells and are
really good for transient expression. I thought there were mutants (ori or
large T) which were inefficient replicators, which theoretically could be
used for maintaining such plasmids. A local DNA tumor virologist tells me
he has used papillomavirus vectors for stable episomal replication. On a
slightly different subject, our lab has been playing with noncytopathic
RNA viruses which can be used to derive stable lines of interest using
cytoplasmic RNA replicons. I predict you may hear about these in the near
future. Anyways, I still think it would be worthwhile to see if the
EBV/hygromycin vector works in the abscence of the EBV/neo vector, possibly
indicating a possible interference phenomenon.
Brett Lindenbach
Program in Immunology
Washington University - St Louis
brett at borcim.wustl.edu
"I own my own pet virus. I get to pet and name her." - Cobain