In another embodiment, the method comprises: testing the mutagenic potential of a nucleoside analog, determining extension by {HEAD ~ HIV RT} of {TAIL ~ the analog}, and comparing incorporation by HIV RT of the analog with incorporation by mammalian DNA polymerase, therefrom determining whether the analog is incorporated preferentially by HIV RT 
of
In another embodiment , the method comprises : testing the mutagenic potential of a nucleoside analog , determining extension by { HEAD ~ HIV RT } of { TAIL ~ the analog } , and comparing incorporation by HIV RT of the analog with incorporation by mammalian DNA polymerase , therefrom determining whether the analog is incorporated preferentially by HIV RT
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH