[Replication kinetic properties of HIV-1 CRF_BC novel drug resistance associated mutations].

Objective: To study the drug sensitivity and analyze the replication kinetics of HIV-1 B and CRF07_BC subtypes with I132L or T139K/R mutations.

Methods: The amino acids in position 132 and 139 of reverse transcriptase (RT) region of the infectious clone PNL4-3 (HIV-1 B subtype) were changed to L and T/R through site mutagenesis. Combined with the previously constructed infectious clone of HIV-1 CRF07_BC subtype with I132L and T139K/R mutations in RT region, mutated PNL4-3 infectious clones were transfected into 293T cells. The infection ability of mutated clones was detected. The drug sensitivity to NNRTIs (TMC-125, DLV, NVP, EFV) and the properties of replication kinetics were also evaluated.

Results: The mutated infectious clones were constructed including PNL4-3-RT-I132L, PNL4-3-RT-T139K and PNL4-3-RT-T139R. The I132L and T139K/R mutations in HIV-1 B and CRF07_BC infectious clones reduced their drug sensitivity to NNRTIs, which accompanied with the increase of EC50 (concentration for 50% of maximal effect). In subtype CRF07_BC, I132L mutation increased EC50 by 2.55, 19.35, 28.05, 6.13 fold, T139K mutation increased EC50 by 4.67, 3.66, 7.35, 3.30 fold, and T139R mutation increased EC50 by 1.82, 4.69, 25.12, 1.89 fold, respectively. In subtype B, I132L increased EC50 by 3.91, 4.61, 6.38, 3.56 fold, T139K increased EC50 by 3.13, 1.78, 2.26, 2.10 fold, T139R increased EC50 by 5.79, 3.99, 5.78, 2.75 fold, respectively. Similar as wild type PNL4-3, the replication ability of 132L/139K/139R mutated infectious clones reached the peak in day 11. However, compared to wild type BC-WT, I132L/T139R mutations delayed the peak time to day 14 and 21.

Conclusion: The novel drug resistance associated mutations I132L and T139K/R can reduce the drug sensitivity to NNRTIs in subtype B and CRF07_BC, and the replication ability of CRF_07BC declined by I132L mutation.