Several reports have recently shown that drug-resistant human immunodeficiency virus type 1 (HIV-1) is often isolated from treatment-naïve patients. We phenotypically analyzed HIV-1 strains isolated from 44 treatment-naïve individuals and found two strains highly resistant (69- and >310-fold) against nevirapine (NVP). Direct sequencing showed these two isolates had a novel mutation, K238S, in reverse transcriptase (RT), but did not have any reported NVP resistance-associated mutation.A 48-h culture in the presence of NVP, however, selected HIV-1 carrying NVP resistance-associated mutations, V106A, V108I, or both, suggesting that minor viral populations of these two isolates had harbored these mutations. Replication kinetic studies of recombinant HIV-1 clones suggested that K238S conferred a significant resistance against NVP, especially when accompanied with V106A (530-fold) or V108I (56-fold). Our study identified a novel NVP resistance-associated mutation, K238S, which could be persistently detected by genotypic assay longer than V106A and V108I during off-treatment period.
- Human immunodeficiency virus type 1
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