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Differences in Enhanced Susceptibilities to
NNRTIs and to Zidovudine in Site-directed Mutants (SDMs) Bearing
K65R, L74V or M184V
 C
Chappey, E Coakley, K Limoli, J Whitcomb and N Parkin. ViroLogic
Inc, South San Francisco CA
We
have previously demonstrated that NNRTI
hypersensitivity (HS)
is associated with thymidine
analog mutations (TAMs). We recently described NNRTI
HS in clinical isolates the NRTI mutations K65R, M184I/V, and T69D/N/S.
Here we use SDMs to define the NNRTI susceptibility patterns of
specific nonTA NAMs and compare these to zidovudine/ZDV (Retrovir)
susceptibility patterns
NL4-3
SDMs were created with the single mutations K65R, L74V and M184V.
Multiple replicates of each SDM, K65R (n=18), L74V (n=20) and M184V
(n=17), were tested in a single cycle phenotyping assay (PhenoSense).
The mean fold change (FC) values were compared to 20 replicates
of the NL4-3 reference using the t-Test.
Results
· For
the three NNRTIs the mean FCs for the NL4-3 reference ranged 0.95-1.01.
· Relative
to reference all SDMs had lower mean FCs for each NNRTI (p<0.0001).
· The
mean FC (SD) for efavirenz/ (Sustiva)
with K65R, L74V and M184V was 0.56 (0.03), 0.67 (0.02) and 0.65
(0.03), respectively.
· The
mean FC (SD) for nevirapine/NVP
(Viramune) with K65R, L74V and M184V was 0.53 (0.05),
0.59 (0.06) and 0.67 (0.05), respectively.
· The
mean FC (SD) for delavirdine/DLV
(Rescriptor) with K65R, L74V and M184V was 0.54 (0.03),
0.68 (0.06) and 0.65 (0.05), respectively.
· For
EFV, K65R showed lower mean FC than both L74V (p<0.0001) and
M184V (p<0.0001).
· L74V
showed lower mean FC to NVP than to EFV or DLV (p<0.0001 for
both).
· By
contrast the mean FC (SD) to ZDV with M184V, L74V and K65R was 0.33
(0.04), 0.49 (0.07) and 0.60 (0.05), respectively.
· The
mean ZDV FC was greater for M184V than L74V (p<0.0001) and was
greater for L74V than K65R (p<0.0001).
Based
on these results, the authors conclude, “The non-TA NAMS K65R, L74V
and M184V enhance susceptibilities to NNRTIs and to ZDV.”
“Discrete
differences between these mutations exist such that EFV susceptibility
is enhanced by K65R>L74V or M184V.”
“ZDV
susceptibility is enhanced by M184V>L74V>K65R.”
“These
observations may have relevance to models exploring the mechanisms
of RTI HS.”
06/15/05
Reference
C
Chappey and others. Differences in Enhanced Susceptibilities to
NNRTIs and to Zidovudine (ZDV) in Site Directed Mutants (SDMs) Bearing
K65R, L74V or M184V. Abstract 95 (poster). XIV International
HIV Drug Resistance Workshop: Basic Principles and Clinical Implications.
June
7-11, 2005. Québec City, Québec, Canada.
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