Objective  To investigate the occurrence and development rules of drug-resistant mutations in CRF01-AE subtype of human immunodeficiency virus type 1 (HIV-1) strain under the pressure of drug selection.

  Methods  Totally 5 HIV-1 CRF01-AE subtype patients with failure of first-line antiretroviral therapy were selected, and blood samples were longitudinally collected during the course of 6 to 8 years of treatment. Genotypic analysis of drug resistance mutations was performed by high throughput sequencing.

  Results  ① All the patients had the M184V mutation and a certain type of non-nucleoside reverse transcriptase inhibitors (NNRTIs) high-frequency major drug resistance mutations at early stage after medication, common sites were K101E, G190A and K103N, and combination of M184V plus G190A plus TAMs was the common mutations. Mutations was still existed after stopping the corresponding drugs or switching to second-line drugs. ② In the process of thymidine analogue mutations (TAMs) formation, 3 patients had TAM2 pathway, 1 patient had TAM1 pathway, and another patient had only TAM2 pathway mutations in the early stage and accumulated TAM1 pathway mutations in the later stage. ③ Three patients formed multi-drug resistance mutations including TAMs, Q151 complex and 69 insertion complexes, and they still failed in treatment after changing the second-line regimen.

  Conclusion  ① CRF01-AE subtype drug resistance patients begin to develop drug resistance mutations at the early stage of drug use, and several mutations gradually lead to clinical drug resistance, so drug resistance mutation monitoring should be carried out as soon as possible. ② TAMs mutations are competitive in two pathways, CRF01-AE favors the TAM2 pathway. As the treatment time is prolonged, the two pathways can produce fusion. ③ It is recommended to carry out drug resistance testing before switching to the second-line protocol. If the resistance mutation against tenofovir (TDF) is found, the second-line regimen may be ineffective.