sentence: To compare fidelity of LEDGF-dependent strand transfer by HIV-1 , BIV and EIAV INs ( herein , fidelity refers to relative efficiency of concerted versus half-site strand transfer ) , the enzymes were incubated with blunt-ended donor DNA molecules containing respective viral RU5 sequences in the presence of supercoiled plasmid DNA ( pGEM ) , and the reaction products were separated in 1.5 % agarose gels .