Retrovirus with LTR-polyA-LTR = garbage?

[Wolfgang Schechinger]

Dear all, 

Luk Vandenberghe who recently replied to my retrovirus problem questions this 
NG just pointed me to a possible problem when having a retroviral construct 
like this:

---pLHCX-backbone-----5'LTR--PSI--HygR--CMV--cDNA-STOP--polyA--3'LTR---

The presence of polyA between the LTRs could lead to premature termination of 
transcription and thus not yield (at least not high titers of) active 
retrovirus. Sounds obvious. 

When transfecting such a construct into packaging cells, then I would be able 
to detect protein expression there, but not get high titer virus.
In consequence when using lacZ as reporter in such a construct, I also would 
detect less "transfected" packaging cells due to less self-infection (in 
comparison to a construct that doesn't have the polyA feature).

Comments and references are extremely welcome.

Regards,
Wo

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Dr. Wolfgang Schechinger
Institute of Biomedical Sciences
Academia Sinica, Taipei, Taiwan R.o.C.

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