1 research outputs found
Biochemical characterization of a multi-drug resistant HIV-1 subtype AG reverse transcriptase: antagonism of AZT discrimination and excision pathways and sensitivity to RNase H inhibitors
We analyzed a multi-drug resistant (MR) HIV-1 re-
verse transcriptase (RT), subcloned from a patient-
derived subtype CRF02
AG, harboring 45 amino acid
exchanges, amongst them four thymidine analog
mutations (TAMs) relevant for high-level AZT (azi-
dothymidine) resistance by AZTMP excision (M41L,
D67N, T215Y, K219E) as well as four substitutions
of the AZTTP discrimination pathway (A62V, V75I,
F116Y and Q151M). In addition, K65R, known to an-
tagonize AZTMP excision in HIV-1 subtype B was
present. Although MR-RT harbored the most signif-
icant amino acid exchanges T215Y and Q151M of
each pathway, it exclusively used AZTTP discrimi-
nation, indicating that the two mechanisms are mu-
tually exclusive and that the Q151M pathway is ob-
viously preferred since it confers resistance to most
nucleoside inhibitors. A derivative was created, ad-
ditionally harboring the TAM K70R and the rever-
sions M151Q as well as R65K since K65R antago-
nizes excision. MR-R65K-K70R-M151Q was compe-
tent of AZTMP excision, whereas other combinations
thereof with only one or two exchanges still pro-
moted discrimination. To tackle the multi-drug resis-
tance problem, we tested if the MR-RTs could still be
inhibited by RNase H inhibitors. All MR-RTs exhibited similar sensitivity toward RNase H inhibitors be-
longing to different inhibitor classes, indicating the
importance of developing RNase H inhibitors further
as anti-HIV drugs