14084
To gain a better understanding of the impact of long terminal repeat ( LTR ) sequence diversity on LTR -directed gene expression in cells of the central nervous system ( CNS ) and immune system , we amplified and cloned LTRs from proviral DNA in HIV-1 -infected peripheral blood .
 ( DNA: LTR, None) , ( DNA: proviral DNA, None) , ( DNA: LTRs, None) , ( DNA: LTR, None) , ( cell type: HIV-1 -infected peripheral blood, None) , ( DNA: LTR -directed gene, None) , ( DNA: long terminal repeat, None) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 ( DNA: LTR, None) , ( DNA: proviral DNA, None) , ( DNA: LTRs, None) , ( DNA: LTR, None) , ( cell type: HIV-1 -infected peripheral blood, None) , ( DNA: LTR -directed gene, None) , ( DNA: long terminal repeat, None) 