retroviral vector

[Sharon Barr]

I am having a difficult time subcloning small PCR products (300 and 700
bp) with EcoRI ends into the EcoRI site of the retroviral vector pBABE. 
Most of my clones are a recombinant species which is smaller than the
vector itself, the rest are religated vector (inspite of CIP treatment). 
Has anyone else had this problem?  Do you think it is a ligation problem
or do you think that the recombination is happening on the plate?  Anyone
have a suggestion?  After 160  miniscreens I'm at my wits' end!  Please
reply via e-mail to barrs01 at doc.mssm.edu

Thanks for any help you can offer!