comparing incorporation by {HEAD ~ HIV RT} of said analog with incorporation by a mammalian DNA polymerase, therefrom determining whether said {TAIL ~ analog} is incorporated preferentially by HIV RT 
comparing incorporation by { HEAD ~ HIV RT } of said analog with incorporation by a mammalian DNA polymerase , therefrom determining whether said { TAIL ~ analog } is incorporated preferentially by HIV RT
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH