Hello guys,

So I am trying clone my insert (promoter+gene of interest) into my lenti transfer vector.

My insert size is 7200bp and the lenti transfer vector I am using is pLenti-Puro (Addgene #39481).

This vector does not contain cPPT or WPRE which increase transduction efficiency.

So briefly this transfer vector looks like this:

5'-cap - 5'LTR - psi - RRE - [CMV promoter - SV40 promoter - PuroR] - 3'LTR

I am planning to get rid of [CMV promoter-SV40 promoter-PuroR] fragment and clone my

insert into that site. Then the vector genome size, which is the size from 5'LTR to 3'LTR, would be about 9.4kb which is a little less than HIV's native genome size (10.2 kb).

But in order to increase the titer, I would like to get rid of some nonessential parts of this transfer vector. For example there is 800bp gap between RRE site and CMV promoter.

So my question is whether it is okay to get rid of that 800bp together with [CMV promober-SV40 promoter-PuroR] fragment. I don't see any essential sequences within that 800bp but then I think there must be a reason for putting that 800bp between RRE and CMV promoter.

Please let me know what you guys think.

Thank you for reading this question :)