*Article* **HIV Drug Resistance Mutations Detection by Next-Generation Sequencing during Antiretroviral Therapy Interruption in China**

**Miaomiao Li 1, Shujia Liang 2, Chao Zhou 3, Min Chen 4, Shu Liang 5, Chunhua Liu 6, Zhongbao Zuo 1, Lei Liu 1, Yi Feng 1, Chang Song 1, Hui Xing 1, Yuhua Ruan 1, Yiming Shao 1 and Lingjie Liao 1,\***


**Abstract:** Patients with antiretroviral therapy interruption have a high risk of virological failure when re-initiating antiretroviral therapy (ART), especially those with HIV drug resistance. Next-generation sequencing may provide close scrutiny on their minority drug resistance variant. A cross-sectional study was conducted in patients with ART interruption in five regions in China in 2016. Through Sanger and next-generation sequencing in parallel, HIV drug resistance was genotyped on their plasma samples. Rates of HIV drug resistance were compared by the McNemar tests. In total, 174 patients were included in this study, with a median 12 (interquartile range (IQR), 6–24) months of ART interruption. Most (86.2%) of them had received efavirenz (EFV)/nevirapine (NVP)-based first-line therapy for a median 16 (IQR, 7–26) months before ART interruption. Sixty-one (35.1%) patients had CRF07\_BC HIV-1 strains, 58 (33.3%) CRF08\_BC and 35 (20.1%) CRF01\_AE. Thirty-four (19.5%) of the 174 patients were detected to harbor HIV drug-resistant variants on Sanger sequencing. Thirty-six (20.7%), 37 (21.3%), 42 (24.1%), 79 (45.4%) and 139 (79.9) patients were identified to have HIV drug resistance by next-generation sequencing at 20% (v.s. Sanger, *p* = 0.317), 10% (v.s. Sanger, *p* = 0.180), 5% (v.s. Sanger, *p* = 0.011), 2% (v.s. Sanger, *p* < 0.001) and 1% (v.s. Sanger, *p* < 0.001) of detection thresholds, respectively. K65R was the most common minority mutation, of 95.1% (58/61) and 93.1% (54/58) in CRF07\_BC and CRF08\_BC, respectively, when compared with 5.7% (2/35) in CRF01\_AE (*p* < 0.001). In 49 patients that followed-up a median 10 months later, HIV drug resistance mutations at >20% frequency such as K103N, M184VI and P225H still existed, but with decreased frequencies. The prevalence of HIV drug resistance in ART interruption was higher than 15% in the survey. Next-generation sequencing was able to detect more minority drug resistance variants than Sanger. There was a sharp increase in minority drug resistance variants when the detection threshold was below 5%.

**Keywords:** HIV drug resistance; sanger sequencing; next-generation sequencing; interrupted antiretroviral therapy
