cDNA to PCR product: problems??

[J.R.]

Hello all,

Been having some trouble lately where none existed before (what else is
new??). I have a set of oligos specific for the 5' and 3' ends of a viral
DI genome which I use on RNA extracted from virus-infected cells to get
cDNA then a PCR product. Unfortunately, I also amplify the viral mRNAs
when I do. No problem, I just gel purify the fragment and geneclean. Yet,
when I run PCR one more time, I get a smear of DNA where the product
should be. I know the PCR reaction (primers, Taq, etc.) is ok because the
controls come out fine. Geneclean recovery is ok by checking on a gel and
the product is not degraded. I cannot figure out the problem here. The
only thing I can think of is a bad cDNA synthesis. This procedure has
worked before, but now it doesn't. Anyone else have a problem similar to
this?