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As shown in Table 1, among the 244 specimens collected, 237 were obtained from male subjects, and the majority (76.2%) became infected through having sex with a man (MSM). These HIV-1-positive individuals were distributed over a wide age range. We divided the patients into two groups based on whether or not they were receiving treatment: 127 were drug-naïve and 117 were treated with first-line drugs. Of the 117 treated subjects, 98 had a treatment duration of less than 6 months, and 19 individuals had been under treatment for more than 6 months.
Characteristic Number gender Male 237 Female 7 Age < 30 107 30–50 103 > 50 31 Unknown 3 Risk factor MSM 186 Heterosexual 52 Unknown 6 On HAART Yes 117 No 127 Drug duration 0–6 months 98 6–12 months 11 > 12 months 8 Successfully sequenced Drug treated 20 Drug naive 100 Subtype CRF01_AE 78 B 1 C 2 CRF07_BC 25 CRF08_BC 1 URF 13 Table 1. Characteristics of all study participants in Suzhou, China
We obtained a total of 120 RT sequences, 100 from the drug-naïve subjects and 20 from the treated subjects. The PR gene was successfully amplified, yielding 87 sequences from the 244 samples, including 78 sequences from drug-naïve individuals and 9 from treated participants. The accession numbers of the sequences analyzed in this study were KY972127–KY972246.
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According to the RIP results (data not shown) and maximum-likelihood tree based on RT fragments (Figure 1), CRF01_AE was found to be the most prominent strain (65.0%), followed by CRF07_BC (20.8%) (Table 1). We identified two subtype C sequences, which were genetically most closely related to the reference sequence from Africa. The unusual close genetic distance and clinical information confirmed that these sequences were a transmitted pair. Furthermore, URFs accounted for a relatively high percentage (13/120, 10.8%) of the total sequences (Table 1). The URFs were not included in the phylogenetic tree and were analyzed separately by Simplot (Supplemental Figure S1). Bootscan analysis showed that their parental strains were CRF01_AE, subtype B and subtype C, and three of them showed the same breakpoints.
Figure 1. Maximum-likelihood phylogenetic tree of the RT gene region from HIV-1-positive individuals. One thousand bootstrap replicates were performed to confirm the reliability of the branching orders (bootstrap values over 70 are indicated at each node). The scale bar represents 5% nucleotide sequence divergence. Samples analyzed in this study are labeled with solid squares.
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Among the 100 drug-naïve individuals, 11% (11/100) harbored six major or accessory drug resistance mutations (L33F, L76V, K70N/E, and V179D/E) in either the PR or RT region at four positions (Table 2). Only L76V was a major mutation in PR, whereas the others were accessory mutations. Furthermore, several "other mutations" were identified in both the PR and RT regions, including L10I/V, V11I, K20I, and A71V/T. A71V was the most prominent mutation identified, which mainly occurred in CRF07_BC in our cohort. In addition, V90I and V106I were identified, which are NNRTI-selected mutations with a very minimal effect on drug resistance.
Mutation Type Mutation Distribution CRF01_AE CRF07_BC URFs PI Other L10I 1 – – L10V 2 – 1 V11I 1 – – K20I 1 – – A71V – 6 – A71T 1 – 1 Accessory L33F 1 – – Major L76V 1 – – RTI Other V90I – 1 – V106I 1 – – NRTI K70N – – 1 K70E 1 – – NNRTI V179D 4 1 – V179E 1 – 2 Table 2. Transmitted drug resistance mutations profile in drug-naïve subjects
With regard to the 20 sequences from treated individuals, the first-line antiviral treatment regimens were as follows: 15 received 3TC+TDF+EFV, two received 3TC+AZT+NVP, one received 3TC+AZT+EFV, one received 3TC+TDF+NVP, and one patient started on a regimen of 3TC+AZT+EFV that was then changed to 3TC+TDF+EFV; 13 harbored at least one major drug resistance mutation (Table 3). The most dominant mutation to NRTIs detected was M184V, which was found in 11 of the 13 samples, followed by D67N, which was found in four samples. The two frequently occurring mutations to NNRTIs were V106M and G190A, with a proportion of 7/13 and 4/13, respectively. All 13 participants showed relatively high resistance to EFV and NVP, and 12 had high resistance to 3TC, 5 individuals showed low or high resistance to TDF, only one (CNSZ70) was highly resistance to AZT contained in the regimen (Table 3).
Patient ID Drug Resistance Mutations Regimen Treatment Duration(months) ART start date Sample date Viral load (date) Predicted Phenotypes NRTI NNRTI NRTI NNRTI AZT 3TC TDF EFV NVP CNSZ12 D67N\M184V K101E\G190A 3TC+AZT+NVP 20 2011/12/3 2013/8/22 1.1*105(2013/10/21);1.3*105(2013/11/22) S H S H H CNSZ16 M184V Y181I 3TC+TDF+NVP 10 2012/10/20 2013/8/28 4*104(2013/11/12); 3.9*105(2013/12/20) 1.2*105(2014/1/21); 6.6*105(2014/2/21) S H S I H CNSZ28 K65R\Y115F\M184V L100I\K103E 3TC+EFV+TDF 2 2015/10/8 2015/12/3 3.14*104(2015/8/21) Undetectable(2016/10.18) S H H H H CNSZ32 M184V V106M\G190A 3TC+EFV+TDF 3 2015/10/10 2016/1/13 1.49*105(2015/7/27) S H S H H CNSZ70 M41L\E44D\D67N\M184V\T215Y K101H\G190A\N348I 3TC+AZT+NVP 48 2011/7/1 2015/8/25 5.52*102(2015/9/4); 8.55*103(2015/11/30) H H L I H CNSZ83 K65R V106M\V179D 3TC+EFV+TDF 3 2015/9/9 2015/12/2 <5.0*102(2015/9/25); 3*105(2016/8/16) S I H H H CNSZ128 M184V V106M\V179E 3TC+EFV+TDF 1 2015/11/9 2015/12/7 <5.0*102(2015/10/16);5.55*102(2016/2/22) <5 *102(2016/4/8) S H S H H CNSZ134 Y188L 3TC+EFV+TDF 1 2015/11/11 2015/12/9 3.4*105(2015/12/18) S S S H H CNSZ149 D67N\K70E\M184V V106M\V179D 3TC+EFV+TDF 11 2015/2/9 2016/1/7 1.5*105(2015/10/18); 2.8*105(2016/1/11) S H L H H CNSZ161 T69N\M184I V90I\K103N\V106I\M230L 3TC+EFV+TDF 3 2015/9/30 2016/1/5 1.6*105(2015/8/21); 5.2*104(2015/10/30) 6.4*105(2016/1/29); 6.6*104(2016/9/13) S H S H H CNSZ235 D67N\M184V V106M\V179D 3TC+AZT+EFV 3TC+TDF+EFV 16 2014/10/28 2016/3/28 2.1*105(2015/10/27); 2.8*104(2016/1/19) S H S H H CNSZ265 M184V V106M\V179D 3TC+TDF+EFV 8 2015/8/19 2016/4/20 6.3*102(2015/8/21); 7.1*105(2016/7/26) S H S H H CNSZ365 D67N\K70R\M184V V106M\G190A\F227V 3TC+TDF+EFV 13 2015/7/1 2016/8/26 2.6*105(2016/6/7); 5.0*105(2016/8/19) S H L H H Table 3. Acquired drug resistance mutations in treated subjects and the predicted phenotypes to NRTIs and NNRTIs
Twelve of the 13 participants (except for patient CNSZ32) that harbored major drug resistance mutations had records on viral loads after the ART start date and sample date (Table 3). Ten had viral loads >1000 IU/mL after the sample dates, and two had a viral load < 500 IU/mL despite the presence of the identified drug resistance mutations.
Drug resistance mutation profiles of the drug-naïve and first-line regimen-treated HIV-1-infected population of Suzhou, China
- Received Date: 19 April 2017
- Accepted Date: 05 July 2017
- Published Date: 07 August 2017
Abstract: Little is known about the prevalence of drug-resistant mutations in HIV-1-positive individuals in Suzhou,China.To elucidate the transmitted drug resistance (TDR) and acquired drug resistance mutation (ADR) profiles,we collected blood specimens from 127 drug-naïve and 117 first-line drugtreated HIV-1-infected individuals sampled from 2014 to 2016 in Suzhou.We successfully amplified pol fragments from 100 drug-naïve and 20 drug-treated samples.We then determined the drugresistant mutations to protease (PR) and reverse-transcriptase (RT) inhibitors according to the Stanford drug resistance database.Overall,11 and 13 individuals had transmitted (drug-naïve group) and acquired (treated group) resistance mutations,respectively.Six transmitted drugresistant mutations were found,including two mutations (L33F and L76V) in the protease region and four (K70N/E and V179D/E) in the RT region.Only L76V was a major mutation,and K70N/E and V179D/E are known to cause low-level resistance to RT inhibitors.All 13 treated participants who had major drug resistance mutations demonstrated intermediate to high resistance to efavirenz and nevirapine,and six had a treatment duration of less than three months.No major mutations to RT inhibitors were found,implying that the epidemic of transmitted resistance mutations was not significant in this area.Our results suggest that more frequent virus load and drug resistance mutation tests should be conducted for individuals receiving antiretroviral treatment,especially for newly treated patients.Our research provides insights into the occurrence of HIV-1 drug resistance in Suzhou and will help to optimize the treatment strategy for this population.